CN117666180A - Electro-optical modulator and optical module - Google Patents
Electro-optical modulator and optical module Download PDFInfo
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- CN117666180A CN117666180A CN202211055490.6A CN202211055490A CN117666180A CN 117666180 A CN117666180 A CN 117666180A CN 202211055490 A CN202211055490 A CN 202211055490A CN 117666180 A CN117666180 A CN 117666180A
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- Optical Modulation, Optical Deflection, Nonlinear Optics, Optical Demodulation, Optical Logic Elements (AREA)
Abstract
The embodiment of the application provides an electro-optic modulator and an optical module, and relates to the technical field of optical communication. The electro-optic modulator includes: a substrate; a first waveguide material layer disposed on the substrate; a second waveguide material layer disposed on the first waveguide material layer, and a first electrode and a second electrode disposed on the first waveguide material layer; the second waveguide material layer includes a first light transmission structure and a second light transmission structure; the first electrode and the second electrode are respectively positioned at two sides of the first light transmission structure in the light transmission direction; the material of the first waveguide material layer and the material of the second waveguide material layer change in the direction of the thermo-optic coefficient.
Description
Technical Field
The present disclosure relates to the field of optical communications technologies, and in particular, to an electro-optical modulator and an optical module.
Background
An optical communication system is a mainstream communication system at present, and in the optical communication system, an electro-optical modulator is often arranged in an optical signal transmitting device, wherein the electro-optical modulator receives a carrier optical signal and an electrical signal, modulates the carrier optical signal according to the electrical signal, generates a modulated optical signal, and transmits the modulated optical signal to an optical signal receiving device through an optical fiber. In order to increase the number of modulated optical signals transmitted in the same optical fiber, a Wavelength Division Multiplexing (WDM) technology is often used in an optical signal transmitting device to combine modulated optical signals with different wavelengths generated by an electro-optical modulator, and the combined modulated optical signals are transmitted to an optical signal receiving device through the same optical fiber.
In an optical communication system, the electro-optical modulation capability of an electro-optical modulator affects the signal quality of a modulated optical signal, which in turn affects the communication quality of the optical communication system. Currently, the electro-optic modulation capability of the existing electro-optic modulator is not ideal, for example, the temperature variation in the environment where the electro-optic modulator is located is relatively large, and the electro-optic modulation capability of the electro-optic modulator will be poor.
Disclosure of Invention
The embodiment of the application provides an electro-optic modulator and an optical module, wherein the electro-optic modulator has better electro-optic modulation capability.
In a first aspect, there is provided an electro-optic modulator comprising: a substrate; a first waveguide material layer disposed on the substrate; a second waveguide material layer disposed on the first waveguide material layer, and a first electrode and a second electrode disposed on the first waveguide material layer; the second waveguide material layer includes a first light transmission structure and a second light transmission structure; the first electrode and the second electrode are respectively positioned at two sides of the first light transmission structure in the light transmission direction; the material of the first waveguide material layer and the material of the second waveguide material layer change in the direction of the thermo-optic coefficient. In the electro-optical modulator provided by the embodiment of the application, since the second waveguide material layer is disposed on the first waveguide material layer, the second waveguide material layer includes the first optical transmission structure and the second optical transmission structure, and then the first optical transmission structure and the portion of the first waveguide material layer in contact with the first optical transmission structure form the first modulation arm of the electro-optical modulator, and the second optical transmission structure and the portion of the first waveguide material layer in contact with the second optical transmission structure form the second modulation arm of the electro-optical modulator. The first electrode and the second electrode are respectively positioned at two sides of the light transmission direction of the first light transmission structure, and when an electric signal is applied to the first electrode and the second electrode, an electric field is formed between the first electrode and the second electrode and is used for adjusting the refractive index of the first waveguide material layer. When the carrier optical signals pass through the first modulation arm and the second modulation arm, the first electrode and the second electrode receive the electric signals, and the refractive index of the first waveguide material layer is adjusted, so that the phase of the passing carrier optical signals is changed, and the function that the electro-optical modulator modulates the carrier optical signals according to the electric signals to generate modulated optical signals is realized. When the carrier light signal passes through the first modulation arm, the light spots of the carrier light signal are distributed in the first light transmission structure and the part of the first waveguide material layer contacted with the first light transmission structure, and when the carrier light signal passes through the second modulation arm, the light spots of the carrier light signal are distributed in the second light transmission structure and the part of the first waveguide material layer contacted with the second light transmission structure. When the temperature of the environment where the electro-optical modulator is located changes, as the direction of change of the thermal-optical coefficient of the material of the first waveguide material layer is opposite to that of the material of the second waveguide material layer, the refractive index of the material of the first waveguide material layer may increase with the increase of the temperature, and the refractive index of the material of the second waveguide material layer may decrease with the increase of the temperature, or the refractive index of the material of the second waveguide material layer increases, that is, the temperature change indicates that the direction of change of the refractive index of the material of the first waveguide material layer is opposite to that of the material of the second waveguide material layer, so that when the temperature change is a predetermined value, the value of the change of the refractive index of the material of the first waveguide material layer and the value of the change of the refractive index of the material of the second waveguide material layer may cancel out a part, so that the refractive index of the whole first modulation arm and/or the second modulation arm does not change with the change of the temperature, thereby improving the electro-optical modulation capability of the electro-optical modulator.
Optionally, the difference between the absolute value of the thermo-optic coefficient of the material of the first waveguide material layer and the absolute value of the thermo-optic coefficient of the material of the second waveguide material layer is smaller than a first preset value. In this alternative, since the difference between the absolute value of the thermo-optic coefficient of the material of the first waveguide material layer and the absolute value of the thermo-optic coefficient of the material of the second waveguide material layer is smaller than the first preset value, the absolute value of the thermo-optic coefficient of the material of the first waveguide material layer and the absolute value of the thermo-optic coefficient of the material of the second waveguide material layer are approximately equal, then, when the temperature changes, the value of the decrease in the refractive index of the material of the first waveguide material layer (or the value of the increase) and the value of the increase in the refractive index of the material of the second waveguide material layer (or the value of the decrease) are also approximately equal, and then the value of the change in the refractive index of the material of the first waveguide material layer and the value of the change in the refractive index of the material of the second waveguide material layer can be approximately completely cancelled, so that the refractive index of the first modulation arm and/or the second modulation arm as a whole does not change following the change in temperature, so that the electro-optic modulation capability of the electro-optic modulator is better.
Optionally, the material of the first waveguide material layer is an electro-optic type optical waveguide material, and the material of the second waveguide material layer is a non-electro-optic type optical waveguide material. In this alternative, the material of the first waveguide material layer is an electro-optic type optical waveguide material, and then the refractive index of the material of the first waveguide material layer is changed under the action of the electric field between the first electrode and the second electrode, and the material of the second waveguide material layer is a non-electro-optic type optical waveguide material, and then the refractive index of the material of the second waveguide material layer is not changed under the action of the electric field between the first electrode and the second electrode. When the carrier light signals with different wavelengths pass through the first modulation arm, the proportion of the light spots of the carrier light signals with different wavelengths distributed in the first light transmission structure and the part of the first waveguide material layer contacted with the first light transmission structure is different, and when the carrier light signals with different wavelengths pass through the second modulation arm, the proportion of the light spots of the carrier light signals with different wavelengths distributed in the second light transmission structure and the part of the first waveguide material layer contacted with the second light transmission structure is different, so that the proportion of the light spots of the carrier light signals with different wavelengths distributed in the first waveguide material layer is different, namely the proportion of the carrier light signals with different wavelengths modulated by the first waveguide material layer is different, thus the half-wave voltage and the drift of the working point of the electro-optic modulator caused by the wavelength change of the carrier light signals can be offset, and the electro-optic modulation capacity of the electro-optic modulator is improved.
Optionally, the difference between the refractive index of the material of the first waveguide material layer and the refractive index of the material of the second waveguide material layer is smaller than a second preset value. In this alternative manner, since the difference between the refractive index of the material of the first waveguide material layer and the refractive index of the material of the second waveguide material layer is smaller than the second preset value, that is, the refractive index of the material of the first waveguide material layer is approximately equal to the refractive index of the material of the second waveguide material layer, and the proportion of the carrier optical signals with different wavelengths modulated by the first waveguide material layer is different, the half-wave voltage and the drift effect of the working point of the electro-optical modulator caused by the wavelength variation of the carrier optical signals are better counteracted, and the electro-optical modulation capability of the electro-optical modulator is further improved.
Optionally, the first waveguide material layer includes a first ridge and a second ridge; the first light transmission structure is arranged on the first ridge bulge, and the second light transmission structure is arranged on the second ridge bulge. In this alternative, the first waveguide material layer may be provided as a ridge waveguide.
Optionally, the first light transmission structure is a ring structure, and the second light transmission structure is a ribbon structure. In this alternative, since the first optical transmission structure is a ring structure and the second optical transmission structure is a strip structure, the first optical transmission structure and a portion of the first waveguide material layer in contact with the first optical transmission structure form a first modulation arm of the electro-optical modulator, also called a micro-ring resonator, and the second optical transmission structure and a portion of the first waveguide material layer in contact with the second optical transmission structure form a second modulation arm of the electro-optical modulator, also called a coupling optical waveguide, which may be specifically a micro-ring modulator.
Optionally, the first light transmission structure and the second light transmission structure are ribbon structures. In this alternative, since the first optical transmission structure is a strip structure and the second optical transmission structure is a strip structure, the electro-optical modulator may specifically be a mach-zehnder (MZ) modulator.
Optionally, a third electrode and a fourth electrode are further disposed on the first waveguide material layer, and the third electrode and the fourth electrode are respectively located at two sides of the second light transmission structure in the light transmission direction. In this alternative, when the first electrode and the second electrode are located on both sides of the light transmission direction of the first light transmission structure, respectively, an electric field is formed between the first electrode and the second electrode when an electric signal is applied to the first electrode and the second electrode, the electric field being used to adjust the refractive index of the first waveguide material layer, in particular, the refractive index of the first waveguide material layer in the first modulation arm; when the third electrode and the fourth electrode are respectively located at two sides of the light transmission direction of the second light transmission structure, an electric field is formed between the third electrode and the fourth electrode when an electric signal is applied to the third electrode and the fourth electrode, and the electric field is used for adjusting the refractive index of the first waveguide material layer, specifically the refractive index of the first waveguide material layer in the second modulation arm. The electro-optic modulator is a dual-arm driven MZ modulator.
Optionally, the input end of the first optical transmission structure is coupled to the input end of the second optical transmission structure, and the output end of the first optical transmission structure is coupled to the output end of the second optical transmission structure. In this alternative, the electro-optical modulator is a MZ modulator, the input end of the first modulation arm and the input end of the second modulation arm of the MZ modulator receive the carrier optical signal, and the optical signals output by the output end of the first modulation arm and the output end of the second modulation arm of the MZ modulator form a modulated optical signal by interference.
Optionally, the input end of the first optical transmission structure is coupled with the first output end of the first coupler, and the input end of the second optical transmission structure is coupled with the second output end of the first coupler; the output end of the first optical transmission structure is coupled with the first input end of the second coupler, and the output end of the second optical transmission structure is coupled with the second input end of the second coupler. In this alternative, the electro-optic modulator is a MZ modulator, the input of the first coupler receives the carrier optical signal, the first coupler transmits the carrier optical signal to the input of the first optical transmission structure coupled to the first input of the first coupler, and the first coupler also transmits the carrier optical signal to the input of the second optical transmission structure coupled to the second input of the first coupler, such that the first and second modulation arms of the MZ modulator receive the carrier optical signal. The output end of the first optical transmission structure is coupled to the first input end of the second coupler, the output end of the second optical transmission structure is coupled to the second input end of the second coupler, in the second coupler, the optical signals output by the first modulation arm and the second modulation arm form a modulated optical signal through interference, and the output end of the second coupler outputs the modulated optical signal.
Optionally, the material of the first waveguide material layer includes: lithium niobate, silicon.
Optionally, the material of the second waveguide material layer includes: titanium dioxide.
Optionally, an oxygen buried layer is further disposed between the substrate and the first waveguide material layer.
In a second aspect, there is provided an electro-optic modulator comprising: a substrate; a first waveguide material layer disposed on the substrate; a second waveguide material layer disposed on the first waveguide material layer, and a first electrode and a second electrode disposed on the first waveguide material layer; the second waveguide material layer includes a first light transmission structure and a second light transmission structure; the first electrode and the second electrode are respectively positioned at two sides of the first light transmission structure in the light transmission direction; the first waveguide material layer is made of electro-optical type optical waveguide material, and the second waveguide material layer is made of non-electro-optical type optical waveguide material. In the electro-optical modulator provided by the embodiment of the application, since the second waveguide material layer is disposed on the first waveguide material layer, the second waveguide material layer includes the first optical transmission structure and the second optical transmission structure, and then the first optical transmission structure and the portion of the first waveguide material layer in contact with the first optical transmission structure form the first modulation arm of the electro-optical modulator, and the second optical transmission structure and the portion of the first waveguide material layer in contact with the second optical transmission structure form the second modulation arm of the electro-optical modulator. The first electrode and the second electrode are respectively positioned at two sides of the light transmission direction of the first light transmission structure, and when an electric signal is applied to the first electrode and the second electrode, an electric field is formed between the first electrode and the second electrode and is used for adjusting the refractive index of the first waveguide material layer. When the carrier optical signals pass through the first modulation arm and the second modulation arm, the first electrode and the second electrode receive the electric signals, and the refractive index of the first waveguide material layer is adjusted, so that the phase of the passing carrier optical signals is changed, and the function that the electro-optical modulator modulates the carrier optical signals according to the electric signals to generate modulated optical signals is realized. When the carrier light signal passes through the first modulation arm, the light spots of the carrier light signal are distributed in the first light transmission structure and the part of the first waveguide material layer contacted with the first light transmission structure, and when the carrier light signal passes through the second modulation arm, the light spots of the carrier light signal are distributed in the second light transmission structure and the part of the first waveguide material layer contacted with the second light transmission structure. The material of the first waveguide material layer adopts an electro-optic type optical waveguide material, so that the refractive index of the material of the first waveguide material layer is changed under the action of an electric field between the first electrode and the second electrode, and the material of the second waveguide material layer adopts a non-electro-optic type optical waveguide material, so that the refractive index of the material of the second waveguide material layer is not changed under the action of the electric field between the first electrode and the second electrode. When the carrier light signals with different wavelengths pass through the first modulation arm, the proportion of the light spots of the carrier light signals with different wavelengths distributed in the first light transmission structure and the part of the first waveguide material layer contacted with the first light transmission structure is different, and when the carrier light signals with different wavelengths pass through the second modulation arm, the proportion of the light spots of the carrier light signals with different wavelengths distributed in the second light transmission structure and the part of the first waveguide material layer contacted with the second light transmission structure is different, so that the proportion of the light spots of the carrier light signals with different wavelengths distributed in the first waveguide material layer is different, namely the proportion of the carrier light signals with different wavelengths modulated by the first waveguide material layer is different, thus the half-wave voltage and the drift of the working point of the electro-optic modulator caused by the wavelength change of the carrier light signals can be offset, and the electro-optic modulation capacity of the electro-optic modulator is improved.
Optionally, the difference between the refractive index of the material of the first waveguide material layer and the refractive index of the material of the second waveguide material layer is smaller than a third preset value. In this alternative manner, since the difference between the refractive index of the material of the first waveguide material layer and the refractive index of the material of the second waveguide material layer is smaller than the second preset value, that is, the refractive index of the material of the first waveguide material layer is approximately equal to the refractive index of the material of the second waveguide material layer, and the proportion of the carrier optical signals with different wavelengths modulated by the first waveguide material layer is different, the half-wave voltage and the drift effect of the working point of the electro-optical modulator caused by the wavelength variation of the carrier optical signals are better counteracted, and the electro-optical modulation capability of the electro-optical modulator is further improved.
Optionally, the first waveguide material layer includes a first ridge and a second ridge; the first light transmission structure is arranged on the first ridge bulge, and the second light transmission structure is arranged on the second ridge bulge. In this alternative, the first waveguide material layer may be provided as a ridge waveguide.
Optionally, the first light transmission structure is a ring structure, and the second light transmission structure is a ribbon structure. In this alternative, since the first optical transmission structure is a ring structure and the second optical transmission structure is a strip structure, the first optical transmission structure and a portion of the first waveguide material layer in contact with the first optical transmission structure form a first modulation arm of the electro-optical modulator, also called a micro-ring resonator, and the second optical transmission structure and a portion of the first waveguide material layer in contact with the second optical transmission structure form a second modulation arm of the electro-optical modulator, also called a coupling optical waveguide, which may be specifically a micro-ring modulator.
Optionally, the first light transmission structure and the second light transmission structure are ribbon structures. In this alternative, since the first optical transmission structure is a strip structure and the second optical transmission structure is a strip structure, the electro-optical modulator may specifically be a mach-zehnder (MZ) modulator.
Optionally, a third electrode and a fourth electrode are further disposed on the first waveguide material layer, and the third electrode and the fourth electrode are respectively located at two sides of the second light transmission structure in the light transmission direction. In this alternative, when the first electrode and the second electrode are located on both sides of the light transmission direction of the first light transmission structure, respectively, an electric field is formed between the first electrode and the second electrode when an electric signal is applied to the first electrode and the second electrode, the electric field being used to adjust the refractive index of the first waveguide material layer, in particular, the refractive index of the first waveguide material layer in the first modulation arm; when the third electrode and the fourth electrode are respectively located at two sides of the light transmission direction of the second light transmission structure, an electric field is formed between the third electrode and the fourth electrode when an electric signal is applied to the third electrode and the fourth electrode, and the electric field is used for adjusting the refractive index of the first waveguide material layer, specifically the refractive index of the first waveguide material layer in the second modulation arm. The electro-optic modulator is a dual-arm driven MZ modulator.
Optionally, the input end of the first optical transmission structure is coupled to the input end of the second optical transmission structure, and the output end of the first optical transmission structure is coupled to the output end of the second optical transmission structure. In this alternative, the electro-optical modulator is a MZ modulator, the input end of the first modulation arm and the input end of the second modulation arm of the MZ modulator receive the carrier optical signal, and the optical signals output by the output end of the first modulation arm and the output end of the second modulation arm of the MZ modulator form a modulated optical signal by interference.
Optionally, the input end of the first optical transmission structure is coupled with the first output end of the first coupler, and the input end of the second optical transmission structure is coupled with the second output end of the first coupler; the output end of the first optical transmission structure is coupled with the first input end of the second coupler, and the output end of the second optical transmission structure is coupled with the second input end of the second coupler. In this alternative, the electro-optic modulator is a MZ modulator, the input of the first coupler receives the carrier optical signal, the first coupler transmits the carrier optical signal to the input of the first optical transmission structure coupled to the first input of the first coupler, and the first coupler also transmits the carrier optical signal to the input of the second optical transmission structure coupled to the second input of the first coupler, such that the first and second modulation arms of the MZ modulator receive the carrier optical signal. The output end of the first optical transmission structure is coupled to the first input end of the second coupler, the output end of the second optical transmission structure is coupled to the second input end of the second coupler, in the second coupler, the optical signals output by the first modulation arm and the second modulation arm form a modulated optical signal through interference, and the output end of the second coupler outputs the modulated optical signal.
Optionally, the material of the first waveguide material layer includes: lithium niobate, silicon.
Optionally, the material of the second waveguide material layer includes: titanium dioxide.
Optionally, an oxygen buried layer is further disposed between the substrate and the first waveguide material layer.
In a third aspect, there is provided an optical module comprising an optical source and an electro-optic modulator as claimed in any one of the first or second aspects, the optical source being arranged to generate a carrier optical signal for transmission to the electro-optic modulator; and the electro-optical modulator is used for modulating the carrier optical signal according to the electric signal to generate a modulated optical signal.
The technical effects of any possible implementation manner of the third aspect may be referred to the technical effects of any different implementation manner of the first aspect or the second aspect, which are not described herein.
Drawings
Fig. 1 is a schematic structural diagram of an optical communication system according to an embodiment of the present application;
fig. 2 is a schematic structural diagram of an optical signal transmitting device in an optical communication system according to an embodiment of the present application;
fig. 3 is a schematic diagram of an optical module according to an embodiment of the present disclosure;
fig. 4 is a schematic perspective view of an electro-optical modulator according to an embodiment of the present application;
FIG. 5 is a top view of the electro-optic modulator shown in FIG. 4;
FIG. 6 is a cross-sectional view of the electro-optic modulator shown in FIG. 5 along AA';
FIG. 7 is a schematic diagram of an electro-optic modulator according to an embodiment of the present application;
FIG. 8 is a top view of an electro-optic modulator provided in accordance with yet another embodiment of the present application;
FIG. 9 is a schematic perspective view of an electro-optic modulator according to another embodiment of the present disclosure;
FIG. 10 is a cross-sectional view along AA' of the electro-optic modulator of FIG. 9 in a top view;
FIG. 11 is a schematic perspective view of an electro-optic modulator according to another embodiment of the present disclosure;
FIG. 12 is a top view of the electro-optic modulator shown in FIG. 11;
fig. 13 is a schematic perspective view of an electro-optical modulator according to another embodiment of the present application.
Detailed Description
The following description of the technical solutions in the embodiments of the present application will be made with reference to the drawings in the embodiments of the present application, and it is apparent that the described embodiments are only some embodiments of the present application, but not all embodiments.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. In embodiments of the present application, "at least one" means one or more, and "a plurality" means two or more. "and/or", describes an association relationship of an association object, and indicates that there may be three relationships, for example, a and/or B, and may indicate: a alone, a and B together, and B alone, wherein a, B may be singular or plural. The character "/" generally indicates that the context-dependent object is an "or" relationship. "at least one of" or the like means any combination of these items, including any combination of single item(s) or plural items(s). For example, at least one (one) of a, b or c may represent: a, b, c, a and b, a and c, b and c or a, b and c, wherein a, b and c can be single or multiple. In addition, in the embodiments of the present application, the words "first", "second", and the like do not limit the number and order.
Furthermore, in the embodiments of the present application, the terms "upper," "lower," and the like, are defined with respect to the orientation in which the components in the drawings are schematically disposed, and it should be understood that these directional terms are relative concepts, which are used for descriptive and clarity with respect thereto, and which may be varied accordingly with respect to the orientation in which the components in the drawings are disposed.
It should be noted that, in the embodiments of the present application, words such as "exemplary" or "such as" are used to mean serving as an example, instance, or illustration. Any embodiment or design described herein as "exemplary" or "e.g." is not necessarily to be construed as preferred or advantageous over other embodiments or designs. Rather, the use of words such as "exemplary" or "such as" is intended to present related concepts in a concrete fashion.
The technical solutions in the embodiments of the present application will be described below with reference to the accompanying drawings.
Referring to fig. 1, an embodiment of the present application provides a schematic structural diagram of an optical communication system, and in an optical communication system 100, the optical communication system includes a signal processor 10, an optical signal transmitting device 20, an optical fiber 30, and an optical signal receiving device 40. Wherein the signal processor 10 processes data information such as voice, image, etc., generates an electrical signal, and transmits the electrical signal to the optical signal transmission device 20. The optical signal transmission device 20 is used for generating an optical signal suitable for transmission in the optical fiber 30 from an electrical signal. The optical fiber 30 transmits the optical signal generated by the optical signal transmitting apparatus 20 to the optical signal receiving apparatus 40. The optical signal receiving apparatus 40 receives the optical signal and extracts information therefrom, and finally obtains data information such as voice, image, etc. corresponding to the electric signal generated by the signal processor 10.
Specifically, referring to fig. 2, in the optical signal transmission apparatus 20, an optical module 21 is included, where the optical module 21 includes an optical source 22 and an electro-optical modulator 23, and the optical source 22 is configured to generate a carrier optical signal, transmit the carrier optical signal to the electro-optical modulator 23, and the electric signal generated by the signal processor 10 is specifically transmitted to the electro-optical modulator 23 in the optical signal transmission apparatus 20, and the electro-optical modulator 23 modulates the carrier optical signal according to the electric signal, generates a modulated optical signal, and transmits the modulated optical signal to the optical signal receiving apparatus 40 through the optical fiber 30.
The optical signal receiving apparatus 40 is provided with an electro-optical demodulator, which receives the modulated optical signal transmitted by the optical signal transmitting apparatus 20 through the optical fiber 30, and demodulates the modulated optical signal to generate an electrical signal, so that the optical signal receiving apparatus 40 extracts information according to the electrical signal, and finally obtains data information such as voice and image corresponding to the electrical signal generated by the signal processor 10.
Illustratively, when the optical communication system 100 shown in fig. 1 uses a wavelength-division multiplexing (WDM) technology, more optical modules 21 will be included in the optical signal transmission apparatus 20, and each optical module 21 will generate a modulated optical signal of one wavelength. The optical signal transmitting apparatus 20 further includes a multiplexer/demultiplexer including a plurality of input terminals and an output terminal, each of the plurality of input terminals of the multiplexer/demultiplexer being coupled to one optical module 21, the output terminal of the multiplexer/demultiplexer being coupled to the optical fiber 30, the multiplexer/demultiplexer receiving the modulated optical signal generated by each of the plurality of optical modules 21, the wavelength of the modulated optical signal generated by any two of the plurality of optical modules 21 being different in one optical signal transmission, so that the multiplexer/demultiplexer multiplexes the modulated optical signals of different wavelengths into one multiplexed optical signal, and the optical signal transmitting apparatus 20 transmits the multiplexed optical signal to the optical signal receiving apparatus 40 through the optical fiber 30. Then, a multiplexer/demultiplexer is also disposed in the optical signal receiving apparatus 40, where the multiplexer/demultiplexer in the optical signal receiving apparatus 40 includes an input end and a plurality of output ends, the optical signal receiving apparatus 40 further includes a plurality of electro-optical demodulators, the input end of the multiplexer/demultiplexer in the optical signal receiving apparatus 40 is coupled to the optical fiber 30, each of the plurality of output ends of the multiplexer/demultiplexer in the optical signal receiving apparatus 40 is coupled to one electro-optical demodulator, the multiplexer/demultiplexer in the optical signal receiving apparatus 40 receives the multiplexed optical signal transmitted by the optical fiber 30 by the optical signal transmitting apparatus 20, demultiplexes the multiplexed optical signal into a plurality of modulated optical signals with a plurality of wavelengths, and transmits the modulated optical signals with a single wavelength to one electro-optical demodulator, which demodulates the modulated optical signal to generate an electrical signal.
The optical communication system 100 shown in fig. 1 may include more or fewer devices, and each of the optical communication devices 100 may also include more or fewer functional devices, for example, the optical signal transmitting device 20 shown in fig. 2 may include more or fewer functional devices, which are not limited in the embodiments of the present application. And the illustrations of fig. 1 and 2 are schematic and do not limit the structure of the optical communication system 100, in other embodiments, the optical module and the electro-optical demodulator may be integrated into one device to implement optical signal transmission and reception.
In an optical communication system, the electro-optical modulation capability of an electro-optical modulator affects the signal quality of a modulated optical signal, which in turn affects the communication quality of the optical communication system. The half-wave voltage of the electro-optic modulator is usually used for measuring the electro-optic modulation function of the electro-optic modulator, and the half-wave voltage of the electro-optic modulator is a voltage value required by pi of phase change in a conversion curve of the electro-optic modulator. The temperature of the environment where the electro-optical modulator is located has an influence on the half-wave voltage, when the environment temperature changes, the half-wave voltage of the electro-optical modulator changes, and when the half-wave voltage of the electro-optical modulator changes, the electro-optical modulator modulates the carrier optical signal according to the electric signal with a preset size, the generated modulated optical signals are different, and the quality of the modulated optical signals is further deteriorated.
In addition, the light source in the optical module can generate a plurality of carrier optical signals with different wavelengths, and when the wavelength of the carrier optical signal generated by the light source changes, the electro-optical modulator needs to modulate the carrier optical signals with different wavelengths according to the electric signal to generate a modulated optical signal. However, the change of the wavelength of the carrier optical signal received by the electro-optical modulator may also affect the half-wave voltage of the electro-optical modulator, and when the wavelength of the carrier optical signal is changed, the half-wave voltage of the electro-optical modulator may also change, which may affect the quality of the modulated optical signal in severe cases.
In order to reduce the influence of wavelength change of a carrier optical signal or change of ambient temperature on half-wave voltage of an electro-optical modulator, a complex peripheral circuit and an optical path are generally arranged in the existing optical module. Referring to fig. 3, a conventional optical module 50 includes a light source 51, an electro-optical modulator 52, a photodetector 53, a lock-in amplifier 54, a signal source 55, and a collimator lens 56. The electro-optical modulator 52 includes a modulation arm 521 and a modulation arm 522. The light source 51 is coupled to the electro-optic modulator 52 and the signal source 55 is coupled to the electro-optic modulator 52. The optical source 51 generates a carrier optical signal, which is transmitted to the electro-optical modulator 52. The signal source 522 transmits an electrical signal to the modulation arm 521 and the modulation arm 522. The carrier optical signal and the electrical signal are received by two modulation arms in the electro-optical modulator 52, and the modulation arm 521 modulates the carrier optical signal according to the electrical signal to generate a first optical signal, and the modulation arm 522 modulates the carrier optical signal according to the electrical signal to generate a second optical signal, and the first optical signal and the second optical signal interfere at an output end of the electro-optical modulator 52 to form a modulated optical signal.
Wherein, the optical module 50 is provided with a feedback circuit, the feedback circuit comprises a light detector 53 and a phase-locked amplifier 54, the light detector 53 is coupled with the electro-optical modulator 52 and the phase-locked amplifier 54, and the phase-locked amplifier 54 is coupled with a signal source 55. Wherein the electro-optic modulator 52 transmits the modulated optical signal to the optical detector 53; the photodetector 53 detects the modulated optical signal, generates a detection electric signal, and transmits the detection electric signal to the lock-in amplifier 54; the lock-in amplifier compares the detected electrical signal with the electrical signal transmitted from the signal source 55 to the modulation arm 522 and the modulation arm 521, determines an offset, and transmits the offset to the signal source 55; the signal source 55 generates a new electrical signal according to the offset, and the voltage magnitude of the new electrical signal is related to the offset. When the signal source 55 transmits a new electrical signal to the modulation arm 522 and the modulation arm 521, the modulation arm 521 modulates the carrier optical signal according to the new electrical signal to generate a new first optical signal, and the modulation arm 522 modulates the carrier optical signal according to the new electrical signal to generate a new second optical signal, so as to eliminate the influence of the change of the wavelength of the carrier optical signal or the change of the ambient temperature on the half-wave voltage of the electro-optical modulator. Alternatively, the additional compensating optical signal may be transmitted to the electro-optical modulator 52, specifically, to the modulation arm 521 of the electro-optical modulator 52 through the collimating lens 56, so that the refractive index of the electro-optical modulator 52 is changed, and the first optical signal and the second optical signal are further changed, so as to eliminate the influence of the wavelength change of the carrier optical signal or the change of the ambient temperature on the half-wave voltage of the electro-optical modulator 52.
Therefore, in the existing optical module, in order to reduce the influence of the wavelength change of the carrier optical signal or the change of the ambient temperature on the half-wave voltage of the electro-optical modulator, a relatively complex peripheral circuit needs to be provided, and when the wavelength of the carrier optical signal is rapidly switched, the peripheral circuit or the optical path cannot respond in time, which can result in limited compensation effect on the modulated optical signal.
To this end, embodiments of the present application provide an electro-optic modulator that has a good electro-optic modulation capability. Referring to fig. 4, an embodiment of the present application provides a schematic perspective view of the electro-optic modulator 23, referring to fig. 5, an embodiment of the present application provides a top view of the electro-optic modulator 23 shown in fig. 4, and referring to fig. 6, an embodiment of the present application provides a cross-sectional view along AA' of the electro-optic modulator 23 shown in fig. 5. Wherein the electro-optical modulator 23 comprises: a substrate 231; a waveguide material layer 232 disposed on the substrate 231; a waveguide material layer 233 disposed on the waveguide material layer 232, and an electrode 234 and an electrode 235 disposed on the waveguide material layer 232; the waveguide material layer 233 includes a light transmission structure s1 and a light transmission structure s2; wherein the electrode 234 and the electrode 235 are respectively located at both sides of the light transmission direction of the light transmission structure s 1; the material of the waveguide material layer 232 is opposite to the direction of change of the thermo-optic coefficient of the material of the waveguide material layer 233.
Illustratively, the electro-optical modulator 23 shown in fig. 4 is a mach-zehnder (MZ) modulator, in which both the optical transmission structure s1 and the optical transmission structure s2 are stripe structures. The input end of the light transmission structure s1 is coupled to the input end of the light transmission structure s2, and the output end of the light transmission structure s1 is coupled to the output end of the light transmission structure s 2. The input end of the optical transmission structure s1 and the input end of the optical transmission structure s2 receive the carrier optical signal, and as shown in fig. 4 and 5, for example, a coupler 237 is further disposed in the electro-optical modulator 23, where the coupler 237 includes an input end, a first output end, and a second output end, the input end of the coupler 237 is coupled to the light source 22, the first output end of the coupler 237 is coupled to the input end of the optical transmission structure s1, and the second output end of the coupler 237 is coupled to the input end of the optical transmission structure s 2. The coupler 237 receives the carrier optical signal generated by the optical source 22, and the coupler 237 transmits the carrier optical signal to the optical transmission structures s1 and s2, wherein the amplitudes and frequencies of the carrier optical signals transmitted in the optical transmission structures s1 and s2 are equal.
Wherein the light transmission structure s1 in fig. 4 and the part of the waveguide material layer 232 in contact with the light transmission structure s1 form a first modulation arm of the electro-optic modulator 23, and the light transmission structure s2 in fig. 4 and the part of the waveguide material layer 232 in contact with the light transmission structure s2 form a second modulation arm of the electro-optic modulator 23. Thus, the carrier optical signal passes through the first modulation arm and the second modulation arm. The first modulation arm generates a third optical signal according to the electric signal and the carrier optical signal, the second modulation arm generates a fourth optical signal according to the electric signal and the carrier optical signal, and because the output end of the optical transmission structure s1 is coupled with the output end of the optical transmission structure s2, the third optical signal and the fourth optical signal interfere at the output end of the optical transmission structure s1 (or the output end of the optical transmission structure s 2), so that coherent constructive or coherent destructive is realized, and a modulated optical signal is generated. As illustrated in fig. 4 and 5, the electro-optical modulator 23 is further provided with a coupler 238, where the coupler 238 includes a first input terminal, a second input terminal, and an output terminal, the first input terminal of the coupler 238 is coupled to the output terminal of the optical transmission structure s1, the second input terminal of the coupler 238 is coupled to the output terminal of the optical transmission structure s2, and the output terminal of the coupler 238 is coupled to the output terminal of the electro-optical modulator 23. The coupler 238 receives the third optical signal in the first modulation arm and the fourth optical signal in the second modulation arm, and the third optical signal and the fourth optical signal interfere in the coupler 238 to implement coherent constructive or coherent destructive, generate a modulated optical signal, and output from an output end of the coupler 238.
Specifically, the electrodes 234 and 235 are connected to an external signal source, which is used to transmit an electrical signal to the electrodes 243 and 235 so that an electric field is formed between the electrodes 234 and 235, and as shown in fig. 5, the voltage difference between the electrodes 234 and 235 is Vrf, and the voltage difference Vrf causes an electric field to be formed between the electrodes 234 and 235. The refractive index of the waveguide material layer 232 will change under the control of the electric field formed between the electrode 234 and the electrode 235. Illustratively, the material of the waveguide material layer 232 includes lithium niobate, silicon. The material in the waveguide material layer 232 is lithium niobate (LiNbO) 3 ) In this case, since lithium niobate changes its refractive index by an applied electric field, this phenomenon is also called an electro-optical effect, and thus a lithium niobate material is also called an electro-optical type material, and is generally manufactured as an optical waveguide material. In order to integrate the electro-optic modulator with conventional semiconductor processes, the material of the waveguide material layer 232 may also be siliconSi), wherein the electro-optical effect of the silicon material is specifically a plasma dispersion effect, wherein the concentration of carriers in the silicon material is changed under the action of an external electric field, and the refractive index of the silicon material is reduced with the increase of the concentration of carriers in the silicon material, so that the purpose of changing the refractive index of the silicon material can be achieved by applying the electric field to the silicon material.
When the refractive index of the waveguide material layer 232 changes with the applied electrical signal, the phase of the carrier optical signal passing through the first modulation arm changes, so as to generate a third optical signal, and the phase of the carrier optical signal passing through the second modulation arm changes, so as to generate a fourth optical signal. Since the output end of the optical transmission structure s1 is coupled to the output end of the optical transmission structure s2, the third optical signal and the fourth optical signal interfere at the output end of the optical transmission structure s1 (or the output end of the optical transmission structure s 2), so as to implement coherent constructive or coherent destructive, thereby generating a modulated optical signal.
The above-described electro-optical modulator 23 is also referred to as a single-arm-driven electro-optical modulator, because the electrode 234 and the electrode 235 are located on both sides of the light transmission structure s1 in the light transmission direction, respectively. The electrical signals transmitted by the external signal source to electrode 243 and electrode 235 include, for example, electrical signals carrying communication information and bias voltages. Referring to fig. 7, an embodiment of the present application provides a schematic diagram of the electro-optical modulator 23, where the abscissa in fig. 7 represents the bias voltage (Vp), and the ordinate in fig. 7 represents the optical power (P), where the electrical signal carrying the communication information is also referred to as a modulated electrical signal, and the electro-optical modulator 23 specifically modulates the carrier optical signal according to the modulated electrical signal to generate the modulated optical signal. The bias voltage is used to control the electro-optical modulator 23 to operate at predetermined operating points including a point (max) of maximum optical power in the transfer curve of the electro-optical modulator 23, a point (min) of minimum optical power in the transfer curve of the electro-optical modulator 23, a forward positive intersection point (quad+), which is intermediate between a point of minimum optical power in the transfer curve of the electro-optical modulator 23 and a point of maximum optical power in the transfer curve of the electro-optical modulator 23, a reverse positive intersection point (quad-) which is intermediate between a point of maximum optical power in the transfer curve of the electro-optical modulator 23 and a point of minimum optical power in the transfer curve of the electro-optical modulator 23, and a 3dB operating point. Where the 3dB operating point is the operating point at which the power of the carrier optical signal decays from 1 to 0.5, the 3dB operating point is near the inverse quadrature point (quad-) in fig. 7 when the electro-optic modulator 23 is an MZ modulator. The MZ modulator mainly modulates the phase of the carrier optical signal. The half-wave voltage of the electro-optical modulator 23, specifically, the difference between the bias voltage corresponding to the point of the transition curve of the electro-optical modulator 23 where the optical power is minimum and the bias voltage corresponding to the point of the transition curve of the electro-optical modulator 23 where the optical power is maximum.
In other embodiments, referring to fig. 8, the waveguide material layer 232 is further provided with an electrode 239 and an electrode 230, where the electrode 239 and the electrode 230 are located on two sides of the light transmission structure s2 in the light transmission direction, respectively. Specifically, the electrode 239 and the electrode 230 are connected to an external signal source for transmitting an electrical signal to the electrode 249 and the electrode 230 so that an electric field is formed between the electrode 239 and the electrode 230, and as shown in fig. 8, a voltage difference between the electrode 239 and the electrode 230 is Vrf, and the voltage difference Vrf forms an electric field between the electrode 239 and the electrode 230. Specifically, the external signal source couples the electrode 234 and the electrode 230 to the ground, so that the electric potential of the electrode 234 and the electrode 230 is 0, and the external signal source transmits an electric signal to the electrode 235 and the electrode 239, so that the electric potential of the electrode 235 and the electrode 239 is Vrf, and according to the placement position of fig. 8, the direction of the electric field applied to the portion of the waveguide material layer 232 in the first modulation arm, which is in contact with the light transmission structure s1, is from top to bottom, and the direction of the electric field applied to the portion of the waveguide material layer 232 in the second modulation arm, which is in contact with the light transmission structure s2, is from bottom to top. Under the control of the electric field formed between the electrode 234 and the electrode 235, the refractive index of the waveguide material layer 232 changes, more specifically, the refractive index of the waveguide material layer 232 in the first modulation arm changes, so as to modulate the carrier optical signal transmitted in the first modulation arm; under the control of the electric field formed between the electrode 239 and the electrode 230, the refractive index of the waveguide material layer 232 changes, more specifically, the refractive index of the waveguide material layer 232 in the second modulation arm changes, and the carrier optical signal transmitted in the second modulation arm is modulated.
In other embodiments, electrodes 235 and 239 shown in fig. 8 may be coupled together, as may an electro-optic modulator comprising three electrodes.
In other embodiments, electrode 234 includes a first sub-electrode and a second sub-electrode; the electrode 235 includes a first sub-electrode and a second sub-electrode; the electrode 239 includes a first sub-electrode and a second sub-electrode; the electrode 230 includes a first sub-electrode and a second sub-electrode. The first sub-electrode of electrode 234 receives the modulated electrical signal (i.e., the modulated electrical signal of the first modulation arm) from the first sub-electrode of electrode 235, the second sub-electrode of electrode 234 receives the bias voltage (i.e., the bias voltage of the first modulation arm) from the second sub-electrode of electrode 235, the first sub-electrode of electrode 239 receives the modulated electrical signal (i.e., the modulated electrical signal of the second modulation arm) from the first sub-electrode of electrode 230, and the second sub-electrode of electrode 239 receives the bias voltage (i.e., the bias voltage of the second modulation arm) from the second sub-electrode of electrode 230.
The embodiment of the present application does not limit the number of electrodes provided in the electro-optical modulator 23.
Where the waveguide material layer 233 is provided as a material having a positive thermo-optical coefficient, the refractive index of the material of the waveguide material layer 232 will increase when the temperature increases, and the refractive index of the material of the waveguide material layer 232 will decrease when the temperature decreases. Then, when the external environment temperature changes, the refractive index of the material of the waveguide material layer 232 will change, which in turn will cause the working point and half-wave voltage of the electro-optical modulator 23 to drift. At this time, if the waveguide material layer 233 is provided as a material having a negative thermo-optical coefficient, the refractive index of the material of the waveguide material layer 233 will decrease when the temperature increases, and the refractive index of the material of the waveguide material layer 232 will increase when the temperature decreases. Then, since the direction of change of the thermo-optic coefficient of the waveguide material layer 232 and the waveguide material layer 233 is opposite, for example, when the temperature increases, the value of the increase in refractive index of the material of the waveguide material layer 232 and the value of the decrease in refractive index of the material of the waveguide material layer 233 may cancel each other out, so that the electro-optic modulator 23 is insensitive to a change in the ambient temperature.
Alternatively, when the waveguide material layer 233 is formed of a material having a negative thermo-optic coefficient, the refractive index of the material of the waveguide material layer 232 may decrease when the temperature increases, and the refractive index of the material of the waveguide material layer 232 may increase when the temperature decreases. When the waveguide material layer 233 is provided as a material having a positive thermo-optical coefficient, the refractive index of the material of the waveguide material layer 233 will increase when the temperature increases, and the refractive index of the material of the waveguide material layer 232 will decrease when the temperature decreases. Then, since the direction of change of the thermo-optic coefficient of the waveguide material layer 232 and the waveguide material layer 233 is opposite, for example, when the temperature increases, the value of the decrease in refractive index of the material of the waveguide material layer 232 and the value of the increase in refractive index of the material of the waveguide material layer 233 cancel each other out, so that the electro-optic modulator 23 is insensitive to a change in ambient temperature.
Illustratively, when the material of the waveguide material layer 232 is lithium niobate, the lithium niobate material has a positive thermo-optic coefficient, and then the material of the waveguide material layer 233 is titanium dioxide (TiO 2 ) The titanium dioxide material has a negative thermo-optic coefficient. Or when the material of the waveguide material layer 232 is silicon, the silicon material has a positive thermo-optic coefficient, and then the material of the waveguide material layer 233 is titanium dioxide (TiO 2 ) The titanium dioxide material has a negative thermo-optic coefficient.
In the above electro-optical modulator, since the waveguide material layer 233 is disposed on the waveguide material layer 232, the waveguide material layer 233 includes the light transmission structure s1 and the light transmission structure s2, and then the light transmission structure s1 and the portion of the waveguide material layer 232 in contact with the light transmission structure s1 form the first modulation arm of the electro-optical modulator 23, and the light transmission structure s2 and the portion of the waveguide material layer 232 in contact with the light transmission structure s2 form the second modulation arm of the electro-optical modulator 23. Wherein the electrode 234 and the electrode 235 are located at both sides of the light transmission direction of the light transmission structure s1, respectively, and when an electric signal is applied to the electrode 234 and the electrode 235, an electric field is formed between the electrode 234 and the electrode 235, which is used to adjust the refractive index of the waveguide material layer 232. Then, when the carrier optical signal passes through the first modulation arm and the second modulation arm, the electrode 232 and the electrode 235 receive the electrical signal, and further adjust the refractive index of the waveguide material layer 232, so that the phase of the passing carrier optical signal changes, and the function of modulating the carrier optical signal by the electro-optical modulator 23 according to the electrical signal to generate the modulated optical signal is realized. Wherein when the carrier optical signal passes through the first modulation arm, the light spot of the carrier optical signal is distributed in the optical transmission structure s1 and the part of the waveguide material layer 232 contacted with the optical transmission structure s1, and when the carrier optical signal passes through the second modulation arm, the light spot of the carrier optical signal is distributed in the optical transmission structure s2 and the part of the waveguide material layer 232 contacted with the optical transmission structure s 2. When the temperature of the environment in which the electro-optical modulator 23 is located changes, since the direction of change of the thermal-optical coefficient of the material of the waveguide material layer 232 is opposite to that of the material of the waveguide material layer 233, the refractive index of the material of the waveguide material layer 233 may be increased with the increase of the temperature, or the refractive index of the material of the waveguide material layer 233 may be decreased with the increase of the temperature, that is, the refractive index of the material of the waveguide material layer 233 is increased, that is, the temperature change indicates that the direction of change of the refractive index of the material of the waveguide material layer 232 is opposite to that of the material of the waveguide material layer 233, then, when the temperature changes by a predetermined value, the value of the change of the refractive index of the material of the waveguide material layer 232 and the value of the change of the refractive index of the material of the second waveguide material layer may cancel out a portion, so that the refractive index of the whole of the first modulation arm and/or the second modulation arm does not change with the change of the temperature, thereby improving the electro-optical modulation capability of the electro-optical modulator 23.
More specifically, the difference between the absolute value of the thermo-optic coefficient of the material of the waveguide material layer 232 and the absolute value of the thermo-optic coefficient of the material of the waveguide material layer 233 is smaller than a first preset value, where the first preset value may be changed according to the performance of the electro-optic modulator 23, and the numerical value of the first preset value is not limited in the embodiments of the present application. The first preset value may be 1×10 -4 When the material of the waveguide material layer 232 is lithium niobate, the thermo-optic coefficient of the lithium niobate material is 3.3x10 at a fixed wavelength of 1550 nanometers (nm) -5 The material of the waveguide material layer 233 is titanium dioxide (TiO 2 ) At a fixed wavelength of 1550nm, the thermo-optic coefficient of the titanium dioxide material is-1×10 -4 K, wherein niobiumThe difference between the absolute value of the thermo-optic coefficient of the lithium acid material and the absolute value of the thermo-optic coefficient of the titanium dioxide material is 6.7X10 -5 K is less than a first preset value of 1 x 10 -4 and/K. Or when the material of the waveguide material layer 232 is silicon, the silicon material is doped to realize the electro-optical modulation function of the electro-optical modulator, wherein the silicon material has a thermo-optical coefficient of 1.86×10 at a fixed wavelength of 1550nm -4 The material of the waveguide material layer 233 is titanium dioxide (TiO 2 ) At a fixed wavelength of 1550nm, the thermo-optic coefficient of the titanium dioxide material is-1×10 -4 K, wherein the difference between the absolute value of the thermo-optic coefficient of the silicon material and the absolute value of the thermo-optic coefficient of the titanium dioxide material is 0.86 x 10 -4 K is less than a first preset value of 1 x 10 -4 and/K. When the difference between the absolute value of the thermo-optic coefficient of the material of the waveguide material layer 232 and the absolute value of the thermo-optic coefficient of the material of the waveguide material layer 233 is smaller than the first preset value, the absolute value of the thermo-optic coefficient of the material of the waveguide material layer 232 and the absolute value of the thermo-optic coefficient of the material of the waveguide material layer 233 are approximately equal, then, when the temperature changes, the value of the decrease (or the increased value) of the refractive index of the material of the waveguide material layer 232 and the value of the increase (or the decreased value) of the refractive index of the material of the waveguide material layer 233 are also approximately equal, and then the value of the change of the refractive index of the material of the waveguide material layer 232 and the value of the change of the refractive index of the material of the waveguide material layer 233 can be approximately completely cancelled, so that the refractive index of the first modulation arm and/or the second modulation arm as a whole does not change following the change of the temperature, so that the electro-optic modulation capability of the electro-optic modulator is better.
When the electro-optical modulator 23 shown in fig. 4, 5, and 6 is an MZ modulator, the external signal source is used to transmit an electrical signal to the electrode 243 and the electrode 235, so as to form an electric field between the electrode 234 and the electrode 235, and the refractive index of the electric field control waveguide material layer 232 is changed, so that the electro-optical modulator 23 modulates the carrier optical signal according to the electrical signal to generate a modulated optical signal. Thus, the material of the waveguide layer 232 is an electro-optic type optical waveguide material having an electro-optic effect, and the refractive index of the electro-optic type optical waveguide material is changed under the control of the applied electric field. When the waveguide material layer 233 is not present in the electro-optic modulator, the carrier optical signals of different wavelengths drift the half-wave voltage and operating point of the electro-optic modulator 23 based on interference principles when in the waveguide material layer 232.
In the electro-optical modulator 23 provided in the embodiment of the present application, the material of the waveguide material layer 232 is an electro-optical type optical waveguide material, and the waveguide material layer 233 is present in the electro-optical modulator 23, where the material of the optical waveguide material layer 233 is a non-electro-optical type optical waveguide material, and then when the refractive index of the waveguide material layer 232 is changed under the control of the electric field between the electrode 234 and the electrode 235, the refractive index of the material of the waveguide material layer 233 is not affected. In addition, when the carrier optical signals with different wavelengths are transmitted through the first modulation arm and/or the second modulation arm, the ratio of the light intensities of the carrier optical signals with different wavelengths distributed in the waveguide material layer 232 and the waveguide material layer 233 is different, so as to form different light spots. Illustratively, when the carrier optical signals with different wavelengths pass through the first modulation arm, the proportion of the light spots of the carrier optical signals with different wavelengths distributed in the optical transmission structure s1 and the part of the waveguide material layer 232 contacted with the optical transmission structure s1 is different, and when the carrier optical signals with different wavelengths pass through the second modulation arm, the proportion of the light spots of the carrier optical signals with different wavelengths distributed in the optical transmission structure s2 and the part of the waveguide material layer 232 contacted with the optical transmission structure s2 is different, so that the proportion of the light spots of the carrier optical signals with different wavelengths distributed in the waveguide material layer 232 is different, that is, the proportion of the carrier optical signals with different wavelengths modulated by the waveguide material layer 232 is different, so that the half-wave voltage of the electro-optical modulator 23 and the drift of the working point caused by the wavelength change of the carrier optical signals can be counteracted, and the electro-optical modulation capability of the electro-optical modulator 23 is improved.
For example, the waveguide material layer 232 may be a lithium niobate material or a silicon material, the lithium niobate material and the silicon material may be electro-optical type optical waveguide materials, the waveguide material layer 233 may be a titanium dioxide material, and the titanium dioxide material may be a non-electro-optical type optical waveguide material. For example, as the wavelength of the carrier optical signal increases, the proportion of the carrier optical signal distributed in the waveguide material layer 233 will become larger, and the proportion of the carrier optical signal distributed in the waveguide material layer 232 will become smaller. Wherein, the refractive index of the electric field control waveguide material layer 232 between the electrode 234 and the electrode 235 is changed, which means that as the wavelength of the carrier optical signal increases, a smaller and smaller proportion of the carrier optical signal is modulated by the waveguide material layer 232, and the refractive index of the electric field control waveguide material layer 233 between the electrode 234 and the electrode 235 is not changed, which means that as the wavelength of the carrier optical signal increases, a larger and larger proportion of the carrier optical signal is not modulated by the waveguide material layer 233. Because the carrier optical signals with different wavelengths form different light spots in the first modulation arm and/or the second modulation arm, the half-wave voltage of the electro-optical modulator 23 and the drift of the working point caused by the change of the wavelength of the carrier optical signals can be counteracted, and the electro-optical modulation capability of the electro-optical modulator 23 is improved.
In other embodiments, the difference between the refractive index of the material of the waveguide material layer 232 and the refractive index of the material of the waveguide material layer 233 is smaller than a second preset value, where the second preset value may be changed according to the performance of the electro-optical modulator 23, and the value of the second preset value is not limited in the embodiments of the present application. For example, the second preset value may be 1, when the material of the waveguide material layer 232 is lithium niobate, the refractive index of the lithium niobate material is 2.286 (refractive index of ordinary o-ray) at a fixed wavelength of 1550nm, and then the material of the waveguide material layer 233 is titanium dioxide (TiO 2), and the refractive index of the titanium dioxide material is 2.47 (refractive index of ordinary o-ray) at a fixed wavelength of 1550nm, wherein the difference between the refractive index of the lithium niobate material and the refractive index of the titanium dioxide material is 0.184, which is less than the second preset value 1. Or when the material of the waveguide material layer 232 is silicon, the material of the waveguide material layer 233 is titanium dioxide (TiO) when the silicon material is doped such that the refractive index of the silicon material is 3.42 (refractive index of ordinary o-ray) at a fixed wavelength of 1550nm 2 ) The refractive index of the titanium oxide material is 2.47 (refractive index of ordinary ray o-ray) at a fixed wavelength of 1550nm, wherein the difference between the refractive index of the silicon material and the refractive index of the titanium oxide material is 0.95, which is smaller than the second preset value of 1. When the difference between the refractive index of the material of the waveguide material layer 232 and the refractive index of the material of the waveguide material layer 233 is smaller than a second preset value, the wave is represented The refractive index of the material of the conductive material layer 232 is approximately equal to that of the material of the waveguide material layer 233, so that the proportion of the light spots of the carrier optical signals with different wavelengths distributed in the waveguide material layer 232 is different, that is, the proportion of the carrier optical signals with different wavelengths modulated by the waveguide material layer 232 is different, so that the half-wave voltage of the electro-optical modulator 23 and the drift of the working point caused by the wavelength change of the carrier optical signals can be counteracted, and the electro-optical modulation capability of the electro-optical modulator 23 is improved.
Illustratively, in the electro-optic modulator 23 shown in fig. 4, 5, and 6, the waveguide material layer 232 may be considered as a planar waveguide, the waveguide material layer 233 is disposed on the waveguide material layer 232, and the waveguide material layer 233 includes the light transmission structure s1 and the light transmission structure s2, where the light transmission structure s1 and the portion of the waveguide material layer 232 in contact with the light transmission structure s1 in fig. 4 form a first modulation arm of the electro-optic modulator 23, the light transmission structure s2 and the portion of the waveguide material layer 232 in contact with the light transmission structure s2 in fig. 4 form a second modulation arm of the electro-optic modulator 23, and the carrier optical signal is transmitted in the first modulation arm and the second modulation arm.
In other embodiments, the waveguide material layer 232 may be a ridge waveguide. Referring to fig. 9 and 10, wherein referring to fig. 9, embodiments of the present application provide a schematic perspective view of the electro-optic modulator 23, referring to fig. 5, embodiments of the present application provide a top view of the electro-optic modulator 23 shown in fig. 9, and referring to fig. 10, embodiments of the present application provide a cross-sectional view of the electro-optic modulator 23 along AA' shown in fig. 5. Wherein the waveguide material layer 232 includes a ridge protrusion h2 and a ridge protrusion h2; the waveguide material layer 233 includes a light transmission structure s1 and a light transmission structure s2, the light transmission structure s1 is disposed on the ridge protrusion h1, and the light transmission structure s2 is disposed on the ridge protrusion h2, wherein the light transmission structure s1, the ridge protrusion h1, and a portion of the waveguide material layer 232 in contact with the ridge protrusion h1 in fig. 9 form a first modulation arm of the electro-optic modulator 23, and the light transmission structure s2, the ridge protrusion h2, and a portion of the waveguide material layer 232 in contact with the ridge protrusion h2 in fig. 9 form a second modulation arm of the electro-optic modulator 23. Specifically, the height and width of the light transmission structure s1 and the ridge protrusion h1 need to ensure that the mode field is not cut off when the carrier light signal is transmitted in the first modulation arm, and the height and width of the light transmission structure s2 and the ridge protrusion h2 need to ensure that the mode field is not cut off when the carrier light signal is transmitted in the second modulation arm.
In other embodiments, referring to fig. 11 and 12, another electro-optic modulator 23 is provided in an embodiment of the present application, wherein referring to fig. 11, the embodiment of the present application provides a schematic perspective view of the electro-optic modulator 23, referring to fig. 12, the embodiment of the present application provides a top view of the electro-optic modulator 23 shown in fig. 11, and referring to fig. 6, the embodiment of the present application provides a cross-sectional view of the electro-optic modulator 23 along AA' shown in fig. 12. In fig. 11 and fig. 12, the electro-optical modulator 23 shown in fig. 4 is a mach-zehnder (MZ) modulator compared to the electro-optical modulator shown in fig. 4, wherein the waveguide material layer 233 includes an optical transmission structure s1 and an optical transmission structure s2, and the optical transmission structure s1 and the optical transmission structure s2 are both a strip-shaped structure. The electro-optical modulator 23 shown in fig. 11 is a micro-ring modulator, the waveguide material layer 233 includes an optical transmission structure s1 and an optical transmission structure s2, the optical transmission structure s1 is a ring structure, and the optical transmission structure s2 is a strip structure, wherein the optical transmission structure s1 and a portion of the waveguide material layer 232 in contact with the optical transmission structure s1 form a first modulation arm of the electro-optical modulator 23, which is also referred to as a micro-ring resonator, and the optical transmission structure s2 and a portion of the waveguide material layer 232 in contact with the optical transmission structure s2 form a second modulation arm of the electro-optical modulator 23, which is also referred to as a coupling optical waveguide.
The operating point of the electro-optical modulator 23 shown in fig. 11 is often a 6dB operating point, where the 6dB operating point is an operating point where the power of the carrier optical signal is attenuated from 1 to 6dB, and the electro-optical modulator shown in fig. 11 also has a half-wave voltage, where the operating point and the half-wave voltage drift with the change of the ambient temperature and/or the wavelength of the carrier optical signal.
As shown in fig. 12, the electrode 234 and the electrode 235 are respectively located at two sides of the light transmission structure s1 in the light transmission direction, and since the light transmission structure s1 is a ring structure, the electrode 234 is circularly located in the ring structure of the light transmission structure s1, and the electrode 235 is annularly disposed around the ring structure of the light transmission structure s 1.
In operation of the electro-optical modulator 23 shown in fig. 11, with reference to the top view of the electro-optical modulator 23 shown in fig. 12, according to the position of placement in fig. 12, a carrier optical signal is input from the left side of the coupling optical waveguide (optical transmission structure s2 in fig. 12), wherein the carrier optical signal is transmitted in the coupling optical waveguide to form a mode field. The distance between the optical transmission structure s1 and the optical transmission structure s2 is usually relatively close, so that the carrier optical signal transmitted in the coupled optical waveguide is transmitted into the micro-ring resonator in the form of evanescent wave. That is, a portion of the carrier optical signal propagating in the coupled optical waveguide is coupled into the micro-ring cavity. Then, when the electrodes 234 and 235 are connected to an external signal source, the external signal source is used to transmit an electrical signal to the electrodes 243 and 235 so that an electric field is formed between the electrodes 234 and 235, as shown in fig. 12, the voltage difference between the electrodes 234 and 235 is Vrf, and the voltage difference Vrf causes an electric field to be formed between the electrodes 234 and 235. Under the control of the electric field formed between the electrode 234 and the electrode 235, the refractive index of the waveguide material layer 232 will change, particularly, the refractive index of the portion of the waveguide material layer 232 in contact with the optical transmission structure s1 changes most significantly, so that resonance occurs when the portion of the carrier optical signal transmitted in the micro-ring resonator satisfies the predetermined condition to form positive feedback on the carrier optical signal transmitted in the coupling waveguide, and the optical intensity will gradually decrease when the portion of the carrier optical signal transmitted in the micro-ring resonator does not satisfy the predetermined condition, thereby outputting the modulated optical signal on the right side of the coupling optical waveguide.
Illustratively, the material of the waveguide material layer 232 includes lithium niobate, silicon. The material in the waveguide material layer 232 is lithium niobate (LiNbO) 3 ) In this case, since lithium niobate changes its refractive index by an applied electric field, this phenomenon is also called an electro-optical effect, and thus a lithium niobate material is also called an electro-optical type material, and is generally manufactured as an optical waveguide material. In order to integrate electro-optic modulators with conventional semiconductor processes, waveguides are typicallyThe material of the material layer 232 may also be silicon (Si), where the electro-optical effect of the silicon material is specifically a plasma dispersion effect, where the concentration of carriers in the silicon material will change under the action of an applied electric field, and the refractive index of the silicon material decreases with the increase of the concentration of carriers in the silicon material, so that the purpose of changing the refractive index of the silicon material can also be achieved by applying an electric field to the silicon material.
When the temperature of the environment in which the electro-optical modulator 23 is located changes, since the direction of change of the thermo-optical coefficient of the material of the waveguide material layer 232 is opposite to that of the material of the waveguide material layer 233, the refractive index of the material of the waveguide material layer 233 may be increased with the increase of the temperature, or the refractive index of the material of the waveguide material layer 233 may be decreased with the increase of the temperature, that is, the refractive index of the material of the waveguide material layer 233 is increased, that is, the temperature change indicates that the direction of change of the refractive index of the material of the waveguide material layer 232 is opposite to that of the material of the waveguide material layer 233, so that when the temperature changes by a predetermined value, the value of the refractive index change of the material of the waveguide material layer 232 and the value of the refractive index change of the material of the second waveguide material layer may cancel out a portion, so that the refractive index of the micro-ring resonant cavity and/or the coupling optical waveguide as a whole does not change with the change of the temperature, thereby improving the electro-optical modulating capability of the electro-optical modulator 23 shown in fig. 11.
More specifically, the difference between the absolute value of the thermo-optic coefficient of the material of the waveguide material layer 232 and the absolute value of the thermo-optic coefficient of the material of the waveguide material layer 233 is smaller than a first preset value, where the first preset value may be changed according to the performance of the electro-optic modulator 23, and the numerical value of the first preset value is not limited in the embodiments of the present application. The first preset value may be 1×10 -4 When the material of the waveguide material layer 232 is lithium niobate, the thermo-optic coefficient of the lithium niobate material is 3.3X10 at a fixed wavelength of 1550nm -5 The material of the waveguide material layer 233 is titanium dioxide (TiO 2 ) At a fixed wavelength of 1550nm, the thermo-optic coefficient of the titanium dioxide material is-1×10 -4 K, wherein the lithium niobate materialThe difference between the absolute value of the thermo-optic coefficient and the absolute value of the thermo-optic coefficient of the titanium dioxide material was 6.7X10 -5 K is less than a first preset value of 1 x 10 -4 and/K. Or when the material of the waveguide material layer 232 is silicon, the silicon material is doped to realize the electro-optical modulation function of the electro-optical modulator, wherein the silicon material has a thermo-optical coefficient of 1.86×10 at a fixed wavelength of 1550nm -4 The material of the waveguide material layer 233 is titanium dioxide (TiO 2 ) At a fixed wavelength of 1550nm, the thermo-optic coefficient of the titanium dioxide material is-1×10 -4 K, wherein the difference between the absolute value of the thermo-optic coefficient of the silicon material and the absolute value of the thermo-optic coefficient of the titanium dioxide material is 0.86 x 10 -5 K is less than a first preset value of 1 x 10 -4 and/K. When the difference between the absolute value of the thermo-optic coefficient of the material of the waveguide material layer 232 and the absolute value of the thermo-optic coefficient of the material of the waveguide material layer 233 is smaller than the first preset value, the absolute value of the thermo-optic coefficient of the material of the waveguide material layer 232 and the absolute value of the thermo-optic coefficient of the material of the waveguide material layer 233 are approximately equal, then, when the temperature changes, the value of the decrease (or the increased value) of the refractive index of the material of the waveguide material layer 232 and the value of the increase (or the decreased value) of the refractive index of the material of the waveguide material layer 233 are also approximately equal, and then the value of the change of the refractive index of the material of the waveguide material layer 232 and the value of the change of the refractive index of the material of the waveguide material layer 233 can be approximately completely cancelled, so that the refractive index of the micro-ring resonant cavity and/or the coupling optical waveguide as a whole does not change with the change of the temperature, so that the electro-optic modulator 23 shown in fig. 11 has better electro-optic modulation capability.
Illustratively, in the electro-optical modulator 23 shown in fig. 11, the material of the waveguide material layer 232 is an electro-optical type optical waveguide material, and the waveguide material layer 233 is present in the electro-optical modulator 23, where the material of the waveguide material layer 233 is a non-electro-optical type optical waveguide material, then when the refractive index of the waveguide material layer 232 is changed by controlling the electric field between the electrode 234 and the electrode 235, the refractive index of the material of the waveguide material layer 233 is not affected. In addition, when the carrier optical signals with different wavelengths are transmitted through the micro-ring resonant cavity and/or the coupling optical waveguide, the ratio of the light intensities of the carrier optical signals with different wavelengths distributed in the waveguide material layer 232 and the waveguide material layer 233 is different, so as to form different light spots. Illustratively, when the carrier optical signals with different wavelengths pass through the micro-ring resonant cavity, the proportion of the light spots of the carrier optical signals with different wavelengths distributed in the optical transmission structure s1 and the part of the waveguide material layer 232 contacted with the optical transmission structure s1 is different, and when the carrier optical signals with different wavelengths pass through the coupling optical waveguide, the proportion of the light spots of the carrier optical signals with different wavelengths distributed in the optical transmission structure s2 and the part of the waveguide material layer 232 contacted with the optical transmission structure s2 is different, so that the proportion of the light spots of the carrier optical signals with different wavelengths distributed in the waveguide material layer 232 is different, that is, the proportion of the carrier optical signals with different wavelengths modulated by the waveguide material layer 232 is different, so that the half-wave voltage of the electro-optic modulator 23 and the drift of the working point caused by the wavelength change of the carrier optical signals can be counteracted, and the electro-optic modulation capability of the electro-optic modulator 23 is improved.
For example, the waveguide material layer 232 may be a lithium niobate material or a silicon material, the lithium niobate material and the silicon material may be electro-optical type optical waveguide materials, the waveguide material layer 233 may be a titanium dioxide material, and the titanium dioxide material may be a non-electro-optical type optical waveguide material. For example, as the wavelength of the carrier optical signal increases, the proportion of the carrier optical signal distributed in the waveguide material layer 233 will become larger, and the proportion of the carrier optical signal distributed in the waveguide material layer 232 will become smaller. Wherein, the refractive index of the electric field control waveguide material layer 232 between the electrode 234 and the electrode 235 is changed, which means that as the wavelength of the carrier optical signal increases, a smaller and smaller proportion of the carrier optical signal is modulated by the waveguide material layer 232, and the refractive index of the electric field control waveguide material layer 233 between the electrode 234 and the electrode 235 is not changed, which means that as the wavelength of the carrier optical signal increases, a larger and larger proportion of the carrier optical signal is not modulated by the waveguide material layer 233. Because the carrier optical signals with different wavelengths form different light spots in the micro-ring resonant cavity and/or the coupling optical waveguide, the half-wave voltage of the electro-optical modulator 23 and the drift of the working point caused by the change of the wavelength of the carrier optical signals can be counteracted, and the electro-optical modulation capability of the electro-optical modulator 23 is improved.
In other embodiments, the difference between the refractive index of the material of the waveguide material layer 232 and the refractive index of the material of the waveguide material layer 233 is smaller than a second preset value, where the second preset value may be changed according to the performance of the electro-optical modulator 23, and the value of the second preset value is not limited in the embodiments of the present application. For example, the second preset value may be 1, when the material of the waveguide material layer 232 is lithium niobate, the refractive index of the lithium niobate material is 2.286 (refractive index of ordinary o-ray) at a fixed wavelength of 1550nm, and then the material of the waveguide material layer 233 is titanium dioxide (TiO 2), and the refractive index of the titanium dioxide material is 2.47 (refractive index of ordinary o-ray) at a fixed wavelength of 1550nm, wherein the difference between the refractive index of the lithium niobate material and the refractive index of the titanium dioxide material is 0.184, which is less than the second preset value 1. Or when the material of the waveguide material layer 232 is silicon, the material of the waveguide material layer 233 is titanium dioxide (TiO) when the silicon material is doped such that the refractive index of the silicon material is 3.42 (refractive index of ordinary o-ray) at a fixed wavelength of 1550nm 2 ) The refractive index of the titanium oxide material is 2.47 (refractive index of ordinary ray o-ray) at a fixed wavelength of 1550nm, wherein the difference between the refractive index of the silicon material and the refractive index of the titanium oxide material is 0.95, which is smaller than the second preset value of 1. When the difference between the refractive index of the material of the waveguide material layer 232 and the refractive index of the material of the waveguide material layer 233 is smaller than the second preset value, the refractive index of the material of the waveguide material layer 232 is approximately equal to the refractive index of the material of the waveguide material layer 233, and therefore, the proportion of the light spots of the carrier light signals with different wavelengths distributed in the waveguide material layer 232 is different, that is, the proportion of the carrier light signals with different wavelengths modulated by the waveguide material layer 232 is different, so that the half-wave voltage of the electro-optical modulator 23 and the drift of the working point caused by the wavelength change of the carrier light signals can be offset, and the electro-optical modulation capability of the electro-optical modulator 23 is improved.
In other embodiments, referring to fig. 13, embodiments of the present application provide a schematic perspective view of the electro-optic modulator 23, referring to fig. 12, embodiments of the present application provide a top view of the electro-optic modulator 23 shown in fig. 13, and referring to fig. 10, embodiments of the present application provide a cross-sectional view of the electro-optic modulator 23 along AA' shown in fig. 12. Wherein the waveguide material layer 232 includes a ridge protrusion h2 and a ridge protrusion h2; the waveguide material layer 233 includes an optical transmission structure s1 and an optical transmission structure s2, the optical transmission structure s1 is disposed on the ridge protrusion h1, the optical transmission structure s2 is disposed on the ridge protrusion h2, wherein the optical transmission structure s1, the ridge protrusion h1 and a part of the waveguide material layer 232 contacting the ridge protrusion h1 in fig. 9 form a micro-ring resonator of the electro-optic modulator 23, and the optical transmission structure s2, the ridge protrusion h2 and a part of the waveguide material layer 232 contacting the ridge protrusion h2 in fig. 9 form a coupling optical waveguide of the electro-optic modulator 23. Specifically, the height and width of the optical transmission structure s1 and the ridge protrusion h1 need to ensure that the mode field is not cut off when the carrier optical signal is transmitted in the micro-ring resonant cavity, and the height and width of the optical transmission structure s2 and the ridge protrusion h2 need to ensure that the mode field is not cut off when the carrier optical signal is transmitted in the coupling optical waveguide.
In some embodiments, referring to the electro-optic modulator 23 shown in any of fig. 4, 9, 11, and 13, the electro-optic modulator 23 further includes an oxygen-buried layer 236, the oxygen-buried layer 236 being disposed between the substrate 231 and the waveguide material layer 232, wherein the oxygen-buried layer may achieve lattice matching.
In some embodiments, referring to the electro-optic modulator 23 shown in either of fig. 4, 9, the coupler 237 and the coupler 238 comprise a substrate 231; a waveguide material layer 232 disposed on the substrate 231; a waveguide material layer 233 disposed on the waveguide material layer 232. Then, the coupler 237 and the coupler 238 can be manufactured simultaneously, so as to improve the integration level of the electro-optic modulator and reduce the complexity of manufacturing the electro-optic modulator.
In any of the electro-optical modulators 23 shown in fig. 4 and 9, the couplers 237 and 238 are couplers with a "Y" branch structure, and in other embodiments, the couplers 237 and 238 may be multimode interference (multimode interference, MMI) couplers or directional couplers (directional coupler), where the MMI couplers and the directional couplers may implement transmitting a carrier optical signal generated by the received optical source 22 to the optical transmission structures s1 and s2, and the MMI couplers and the directional couplers may implement a third optical signal in the received first modulation arm and a fourth optical signal in the received second modulation arm, so that the third optical signal and the fourth optical signal interfere in the couplers to implement coherent constructive or coherent destructive, and generate and output a modulated optical signal. Embodiments of the present application are not limited to the specific configuration of coupler 237 and coupler 238.
In some embodiments, referring to the electro-optic modulator 23 shown in any of fig. 4, 9, 11, and 13, when the material of the waveguide material layer 232 is specifically a silicon material, the manufacturing process of the electro-optic modulator may be integrated with a conventional semiconductor process, so that the manufacturing of the electro-optic modulator 23 is more convenient.
Illustratively, in other embodiments, referring to the electro-optic modulator 23 shown in any one of FIGS. 4, 9, 11, 13, the electro-optic modulator 23 includes a substrate 231; a waveguide material layer 232 disposed on the substrate 231; a waveguide material layer 233 disposed on the waveguide material layer 232, and an electrode 234 and an electrode 235 disposed on the waveguide material layer 232; the waveguide material layer 233 includes a light transmission structure s1 and a light transmission structure s2; wherein the electrode 234 and the electrode 233 are respectively located at both sides of the light transmission direction of the light transmission structure s 1; the material of the waveguide material layer 232 is an electro-optical type optical waveguide material, and the material of the waveguide material layer 233 is a non-electro-optical type optical waveguide material. Illustratively, the material of the waveguide material layer 232 is an electro-optic type optical waveguide material, and the waveguide material layer 233 is present in the electro-optic modulator 23, where the material of the waveguide material layer 233 is a non-electro-optic type optical waveguide material, and then the refractive index of the material of the waveguide material layer 233 is not affected when the refractive index of the waveguide material layer 232 is changed by controlling the electric field between the electrode 234 and the electrode 235. In addition, when the carrier optical signals with different wavelengths are transmitted through the first modulation arm and/or the second modulation arm (micro-ring resonator and/or coupling optical waveguide), the ratio of the light intensities of the carrier optical signals with different wavelengths distributed in the waveguide material layer 232 and the waveguide material layer 233 is different, so as to form different light spots. For example, when the carrier optical signals with different wavelengths pass through the first modulation arm (micro-ring resonator), the light spots of the carrier optical signals with different wavelengths are distributed differently in the optical transmission structure s1 and the portion of the waveguide material layer 232 contacting the optical transmission structure s1, and when the carrier optical signals with different wavelengths pass through the second modulation arm (coupling optical waveguide), the light spots of the carrier optical signals with different wavelengths are distributed differently in the optical transmission structure s2 and the portion of the waveguide material layer 232 contacting the optical transmission structure s2, so that the light spots of the carrier optical signals with different wavelengths are distributed differently in the waveguide material layer 232, that is, the light spots of the carrier optical signals with different wavelengths are modulated differently by the waveguide material layer 232, which can offset the half-wave voltage of the electro-optical modulator 23 and the drift of the operating point caused by the wavelength variation of the carrier optical signals, and improve the electro-optical modulation capability of the electro-optical modulator 23.
For example, the waveguide material layer 232 may be a lithium niobate material or a silicon material, the lithium niobate material and the silicon material may be electro-optical type optical waveguide materials, the waveguide material layer 233 may be a titanium dioxide material, and the titanium dioxide material may be a non-electro-optical type optical waveguide material. For example, as the wavelength of the carrier optical signal increases, the proportion of the carrier optical signal distributed in the waveguide material layer 233 will become larger, and the proportion of the carrier optical signal distributed in the waveguide material layer 232 will become smaller. Wherein, the refractive index of the electric field control waveguide material layer 232 between the electrode 234 and the electrode 235 is changed, which means that as the wavelength of the carrier optical signal increases, a smaller and smaller proportion of the carrier optical signal is modulated by the waveguide material layer 232, and the refractive index of the electric field control waveguide material layer 233 between the electrode 234 and the electrode 235 is not changed, which means that as the wavelength of the carrier optical signal increases, a larger and larger proportion of the carrier optical signal is not modulated by the waveguide material layer 233. Because different light spots are formed in the first modulation arm and/or the second modulation arm (the micro-ring resonant cavity and/or the coupling optical waveguide) of the carrier optical signals with different wavelengths, the half-wave voltage of the electro-optical modulator 23 and the drift of the working point caused by the change of the wavelength of the carrier optical signals can be counteracted, and the electro-optical modulation capability of the electro-optical modulator 23 is improved.
In other embodiments, the difference between the refractive index of the material of the waveguide material layer 232 and the refractive index of the material of the waveguide material layer 233 is less than a third preset value, wherein the third preset value may be based on electricityThe performance of the optical modulator 23 is changed, and the numerical value of the third preset value is not limited in the embodiment of the present application. The third preset value may be 1, when the material of the waveguide material layer 232 is lithium niobate, the refractive index of the lithium niobate material is 2.286 (refractive index of ordinary ray o-ray) at a fixed wavelength of 1550nm, and then the material of the waveguide material layer 233 is titanium dioxide (TiO 2), and the refractive index of the titanium dioxide material is 2.47 (refractive index of ordinary ray o-ray) at a fixed wavelength of 1550nm, wherein the difference between the refractive index of the lithium niobate material and the refractive index of the titanium dioxide material is 0.184, which is smaller than the third preset value 1. Or when the material of the waveguide material layer 232 is silicon, the material of the waveguide material layer 233 is titanium dioxide (TiO) when the silicon material is doped such that the refractive index of the silicon material is 3.42 (refractive index of ordinary o-ray) at a fixed wavelength of 1550nm 2 ) The refractive index of the titanium oxide material is 2.47 (refractive index of ordinary ray o-ray) at a fixed wavelength of 1550nm, wherein the difference between the refractive index of the silicon material and the refractive index of the titanium oxide material is 0.95, which is smaller than the third preset value of 1. When the difference between the refractive index of the material of the waveguide material layer 232 and the refractive index of the material of the waveguide material layer 233 is smaller than the third preset value, the refractive index of the material of the waveguide material layer 232 is approximately equal to the refractive index of the material of the waveguide material layer 233, and therefore, the proportion of the light spots of the carrier light signals with different wavelengths distributed in the waveguide material layer 232 is different, that is, the proportion of the carrier light signals with different wavelengths modulated by the waveguide material layer 232 is different, so that the half-wave voltage of the electro-optical modulator 23 and the drift of the working point caused by the wavelength change of the carrier light signals can be offset, and the electro-optical modulation capability of the electro-optical modulator 23 is improved.
Although the present application has been described in connection with specific features and embodiments thereof, it will be apparent that various modifications and combinations can be made without departing from the spirit and scope of the application. Accordingly, the specification and drawings are merely exemplary illustrations of the present application as defined in the appended claims and are considered to cover any and all modifications, variations, combinations, or equivalents that fall within the scope of the present application. It will be apparent to those skilled in the art that various modifications and variations can be made in the present application without departing from the spirit or scope of the application. Thus, if such modifications and variations of the present application fall within the scope of the claims and the equivalents thereof, the present application is intended to cover such modifications and variations.
Claims (16)
1. An electro-optic modulator, comprising:
a substrate;
a first waveguide material layer disposed on the substrate;
a second waveguide material layer disposed on the first waveguide material layer, and a first electrode and a second electrode disposed on the first waveguide material layer;
the second waveguide material layer comprises a first light transmission structure and a second light transmission structure;
wherein the first electrode and the second electrode are respectively positioned at two sides of the first light transmission structure in the light transmission direction;
The material of the first waveguide material layer and the material of the second waveguide material layer are opposite in change direction of the thermo-optic coefficient.
2. An electro-optic modulator as claimed in claim 1 wherein,
the difference between the absolute value of the thermo-optic coefficient of the material of the first waveguide material layer and the absolute value of the thermo-optic coefficient of the material of the second waveguide material layer is smaller than a first preset value.
3. An electro-optic modulator as claimed in claim 1 or claim 2 wherein,
the material of the first waveguide material layer adopts an electro-optic type optical waveguide material, and the material of the second waveguide material layer adopts a non-electro-optic type optical waveguide material.
4. An electro-optic modulator as claimed in claim 3 wherein,
the difference between the refractive index of the material of the first waveguide material layer and the refractive index of the material of the second waveguide material layer is smaller than a second preset value.
5. An electro-optic modulator, comprising:
a substrate;
a first waveguide material layer disposed on the substrate;
a second waveguide material layer disposed on the first waveguide material layer, and a first electrode and a second electrode disposed on the first waveguide material layer;
the second waveguide material layer comprises a first light transmission structure and a second light transmission structure;
Wherein the first electrode and the second electrode are respectively positioned at two sides of the first light transmission structure in the light transmission direction;
the material of the first waveguide material layer adopts an electro-optic type optical waveguide material, and the material of the second waveguide material layer adopts a non-electro-optic type optical waveguide material.
6. An electro-optic modulator as claimed in claim 5 wherein,
the difference between the refractive index of the material of the first waveguide material layer and the refractive index of the material of the second waveguide material layer is smaller than a third preset value.
7. An electro-optic modulator as claimed in any one of claims 1 to 6 wherein the first layer of waveguide material comprises a first ridge and a second ridge; the first light transmission structure is arranged on the first ridge bulge, and the second light transmission structure is arranged on the second ridge bulge.
8. An electro-optic modulator as claimed in any one of claims 1 to 7 wherein the first light-transmitting structure is a ring-like structure and the second light-transmitting structure is a strip-like structure.
9. An electro-optic modulator as claimed in any one of claims 1 to 7 wherein the first and second light transmission structures are strip-like structures.
10. An electro-optic modulator as claimed in claim 9 wherein,
and a third electrode and a fourth electrode are further arranged on the first waveguide material layer, and the third electrode and the fourth electrode are respectively positioned at two sides of the second light transmission structure in the light transmission direction.
11. An electro-optic modulator as claimed in claim 9 or claim 10, wherein the input of the first optical transmission structure is coupled to the input of the second optical transmission structure and the output of the first optical transmission structure is coupled to the output of the second optical transmission structure.
12. An electro-optic modulator as claimed in claim 9 or claim 10 wherein,
the input end of the first optical transmission structure is coupled with the first output end of the first coupler, and the input end of the second optical transmission structure is coupled with the second output end of the first coupler;
the output end of the first optical transmission structure is coupled with the first input end of the second coupler, and the output end of the second optical transmission structure is coupled with the second input end of the second coupler.
13. An electro-optic modulator as claimed in any one of claims 1 to 12 wherein,
the material of the first waveguide material layer comprises: lithium niobate, silicon.
14. An electro-optic modulator as claimed in any one of claims 1 to 13 wherein,
the materials of the second waveguide material layer include: titanium dioxide.
15. An electro-optic modulator as claimed in any one of claims 1 to 14 wherein,
an oxygen buried layer is further arranged between the substrate and the first waveguide material layer.
16. An optical module comprising a light source and an electro-optical modulator as claimed in any one of claims 1-15,
the light source is used for generating a carrier light signal and transmitting the carrier light signal to the electro-optical modulator;
the electro-optical modulator is used for modulating the carrier optical signal according to the electric signal to generate a modulated optical signal.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202211055490.6A CN117666180A (en) | 2022-08-29 | 2022-08-29 | Electro-optical modulator and optical module |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202211055490.6A CN117666180A (en) | 2022-08-29 | 2022-08-29 | Electro-optical modulator and optical module |
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| CN117666180A true CN117666180A (en) | 2024-03-08 |
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| CN202211055490.6A Pending CN117666180A (en) | 2022-08-29 | 2022-08-29 | Electro-optical modulator and optical module |
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| CN (1) | CN117666180A (en) |
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