WO2019080338A1

WO2019080338A1 - Array type variable optical attenuator and attenuation and manufacturing method thereof

Info

Publication number: WO2019080338A1
Application number: PCT/CN2017/118178
Authority: WO
Inventors: 徐晓辉; 陈辉; 张伊; 丁丽; 周天红; 马卫东
Original assignee: 武汉光迅科技股份有限公司
Priority date: 2017-10-27
Filing date: 2017-12-25
Publication date: 2019-05-02
Also published as: CN107608029A

Abstract

An array type variable optical attenuator and an attenuation and manufacturing method thereof<u>.</u> The variable optical attenuator adopts curved optical waveguide structures (16, 17), and is capable of reducing optical crosstalk in an adjacent channel caused by stray light leaked from an input end thereof. A deeply etched heat-insulation recess (23) is arranged between channels, and is filled with a polymer material exhibiting low heat transfer and thermal expansion performance, thereby effectively preventing cross transfer of heat between the respective channels.

Description

Array dimmable optical attenuator and attenuation thereof

Technical field

The invention relates to an attenuator and a method for attenuating and manufacturing the same, and relates to the field of optical communication, in particular to an array tunable optical attenuator and a method for attenuating and manufacturing the same.

Background technique

Variable Optical Attenuation (VOA) is an indispensable device in DWDM (Dense Wavelength Division Multiplexing) optical communication signal transmission system. Its function and function is to balance and adjust the amplitude of optical signals to realize signal Effective transmission and reception. At present, the tunable optical attenuator has various types of manufacturing technologies, and can be roughly classified into discrete low-light component technology, micro-electromechanical system (MEMS) technology, and Planar Lightwave Circuit (PLC) technology. Among them, the Mach-Zehnder Interferometer (MZI) type VOA manufactured by the thermo-optic effect PLC technology has the advantages of good stability, small size, low cost, easy integration, and suitable for mass production. One of the dimmable attenuators used.

Generally, the input and output optical waveguides of the MZI type VOA optical path structure based on the thermo-optic effect PLC technology are designed as straight waveguides. As shown in Fig. 1, when the array tunable optical attenuator is made, the stray light formed by the light leakage at the input end is easy to be Adjacent channels generate optical interference, which leads to poor optical performance of the device, such as large polarization-dependent loss and large optical crosstalk. In addition, VOA based on thermo-optic effect generally has high power consumption, which is easy to affect when fabricated into an array structure. Light attenuation in adjacent channels causes thermal crosstalk.

Summary of the invention

The present invention mainly solves the above technical problems existing in the prior art, and provides an array tunable optical attenuator and a manufacturing method thereof. The attenuator and its attenuation and fabrication method adopt a curved optical waveguide structure design, which can reduce the optical crosstalk generated by the stray light formed by the light leakage at the input end to the adjacent channel; and the deep etched heat insulating groove design between the channels Filling the tank with low thermal conductivity and low expansion performance of the Polymer material can effectively isolate the cross heat conduction between the channels.

The above technical problems of the present invention are mainly solved by the following technical solutions:

An array tunable optical attenuator comprising at least one channel unit, the channel unit comprising at least two mutually independent modulated optical waveguides and a heating electrode disposed on the at least one modulated optical waveguide; and the modulated optical waveguide The input optical waveguide and/or the output optical waveguide have a curved portion that blocks light leakage to prevent leakage of light from coupling with the modulated optical waveguide.

Preferably, in the above array tunable optical attenuator, each modulated optical waveguide is split on the same input optical waveguide and converges on the same output optical waveguide.

Preferably, in the above array tunable optical attenuator, the heating electrode is connected with an electrode lead of a conductive function at both ends.

Preferably, in the above array tunable optical attenuator, the number of channel units is several, and a heat insulating slot is disposed between adjacent channel units.

Preferably, in the above array dimming attenuator, the heat insulating groove is filled with a polymer having a thermal conductivity of less than 0.026 W/(m.k) and a thermal expansion coefficient of less than 0.5×10^-6/K.

Preferably, in the above array tunable optical attenuator, the heating electrode has a resistivity of 50 to 500 nΩ·m; and/or the electrode lead connected to the heating electrode has an electric conductivity of 60 to 110% IACS.

Preferably, in the above array tunable optical attenuator, the heating electrode is provided with a metal film anti-oxidation protective layer.

An array dimming attenuation method includes:

Integrating the optical signal from the input curved optical waveguide into the attenuator and dividing the optical signal into at least two transmission optical paths;

The curved portion of the input optical waveguide and/or the output optical waveguide blocks light leakage of the input optical waveguide and/or the output optical waveguide to prevent leakage of light from coupling with the modulated optical waveguide;

Heating at least one transmission optical path to change a phase of the optical signal of the optical path;

The optical signals of the respective transmission optical paths are superimposed to achieve attenuation of the optical signal.

Preferably, the method for fabricating the array dimmable attenuator described above comprises:

Forming a silicon dioxide undercladding layer on the substrate, depositing a waveguide core layer on the lower cladding layer;

Etching the optical path of the dimmable optical attenuator array on the waveguide chip;

Depositing a silicon dioxide over cladding layer encasing the waveguide chip, and forming a heating electrode layer adjacent to the waveguide core layer on the upper cladding layer;

Wherein, when etching the optical path of the tunable optical attenuator array, the input optical waveguide and/or the output optical waveguide having a curved portion that blocks light leakage to prevent light leakage from coupling with the modulated optical waveguide is etched.

A heat insulating groove is etched between the channels, and the porous material is filled in the heat insulating groove;

and / or

A metal thin film anti-oxidation protective layer covering the heating electrode layer is formed on the upper cladding layer.

Therefore, the present invention has the following advantages:

1. Since the input optical waveguide and the output optical waveguide adopt a curved optical waveguide structure design, the optical crosstalk generated by the stray light formed by the light leakage at the input end to adjacent channels can be reduced, thereby improving device performance, such as polarization dependent loss and optical crosstalk reduction. Small.

2. Due to the design of the deep-etched heat-insulating groove between the channels, and filling the groove with the low thermal conductivity and low expansion performance of the Polymer material, the cross-heat conduction between the channels can be effectively isolated, thereby reducing the thermal cross-talk to the light attenuation. Influence to achieve the purpose of improving attenuation accuracy.

DRAWINGS

1 is a schematic structural view of a planar optical waveguide MZI type VOA in the prior art;

2 is a schematic structural view of a planar optical waveguide MZI type VOA provided by the present invention;

Figure 3 is a schematic cross-sectional view of Figure 2;

4 is a schematic structural view of an array tunable optical attenuator provided by the present invention;

5 is a schematic diagram of a manufacturing process of an array tunable optical attenuator provided by the present invention;

among them:

10: Input direct optical waveguide 11: upper modulated optical waveguide

12: Lower modulated optical waveguide 13: Heating electrode

14: Electrode lead 15: Output direct optical waveguide

16: Input curved optical waveguide 17: Output curved optical waveguide

18: upper cladding 19: waveguide core layer

20: lower cladding 21: silicon based wafer substrate

22: Metal film anti-oxidation protective layer 23: Insulation tank.

Detailed ways

The technical solutions of the present invention will be further specifically described below by way of embodiments and with reference to the accompanying drawings.

Example:

As shown in FIG. 4, an array tunable optical attenuator according to an embodiment of the present invention is configured by a plurality of tunable optical attenuator array configurations.

As shown in FIG. 2, the photoelectric structure of the tunable optical attenuator comprises: an input curved optical waveguide 16, an upper modulated optical waveguide 11, a lower modulated optical waveguide 12, and an output curved optical waveguide 17 to have an adjustment and a straight-through function. The optical path structure; the heating circuit is composed of the heating electrode 13 and the electrode lead 14. The bending angle α of the input curved optical waveguide is any angle greater than 0 degrees and less than 360 degrees; the bending angle β of the output curved optical waveguide is any angle greater than 0 degrees and less than 360 degrees. The heating electrode is disposed on the upper modulated optical waveguide or the lower modulated optical waveguide or on the upper and lower modulated optical waveguides, and the conductive electrodes are connected at both ends of the heating electrode.

As shown in FIG. 5, a method for fabricating an array tunable optical attenuator according to an embodiment of the present invention includes:

Step S1: using a wet thermal oxidation method, a layer of silica undercoat layer 20 is oxidized on the silicon-based wafer substrate 21;

Step S2: depositing a waveguide core layer 19 on the lower cladding layer 20 by chemical vapor deposition;

Step S3: forming a tunable optical attenuator array optical path by using a reactive ion etching technique on the waveguide core layer 19;

Step S4: depositing a layer of silicon dioxide overlayer 18 by chemical vapor deposition;

Step S5: etching the heat insulating groove 23 between the channels by using a deep etching technique;

Step S6: The porous material is filled in the heat insulating tank 23 by spin coating.

Step S7: forming a heating electrode layer 13 and a heating electrode lead layer 14 on the upper cladding layer 18 by a metal thin film deposition process;

Step S8: forming a metal film anti-oxidation protective layer 22 by a plasma chemical vapor deposition process;

Step S9: after high temperature annealing and high pressure processing, completing wafer processing;

Step S10: wafer cutting, completing the fabrication of the array dimmable attenuator chip.

Wherein the refractive index of the waveguide core layer silica material is slightly larger than the refractive index of the lower cladding layer and the upper cladding layer silica material, and the thickness of the upper cladding layer and the lower cladding layer is the thickness of the waveguide core layer 3 to 5 times to ensure that the optical signal is transmitted efficiently in the waveguide core layer.

The insulated tank 23 is located in the middle of the two channels.

The polymer material is a polymer having a thermal conductivity of less than 0.026 W/(m.k) and a thermal expansion coefficient of less than 0.5×10^-6/K.

The heating electrode 13 is made of a metal or an alloy having a resistivity of 50 to 500 nΩ·m, and the electrode lead 14 is made of a metal or alloy having an electric conductivity of 60 to 110% IACS.

The heating electrode 13 is made of one of titanium, tungsten, chromium, platinum or any combination; the electrode lead 14 is made of one of gold, copper, aluminum or any combination.

The material of the metal film anti-oxidation protective layer 22 is silicon nitride to protect the heating electrode layer and the heating electrode lead layer from oxidation.

The optical path process of the tunable optical attenuator according to the embodiment of the present invention is as follows: the optical signal enters the attenuator from the input curved optical waveguide 16 and is then equally divided into upper and lower paths. The upper modulated optical waveguide 11 is an adjustment branch on which the heating electrode 13 is plated, and by using the thermo-optic effect of silicon dioxide, the refractive index of the material is changed by changing the temperature of the waveguide material, and the voltage is applied to the heating electrode 13 as needed. The heat is generated and the heat is transferred to the upper modulated optical waveguide core layer 19 to achieve temperature adjustment, so that the phase of the optical signal changes, so that the signal of the upper modulated optical waveguide 11 is adjusted by the phase shift and the optical signal of the lower modulated optical waveguide 12 is in the light. The waveguide output terminal 17 interferes. The two signals with the same phase and amplitude are adjusted to become two signals whose amplitudes are still equal but different in phase. After superposition, the intensity of the original signal is changed to achieve the attenuation of the optical signal. The function of the heat insulating groove 23 in the figure is to isolate the multi-channel cross heat conduction, which can reduce the influence of the heat crosstalk on the light attenuation, so as to achieve the purpose of improving the attenuation precision.

The specific embodiments described herein are merely illustrative of the spirit of the invention. A person skilled in the art can make various modifications or additions to the specific embodiments described or in a similar manner, without departing from the spirit of the invention or as defined by the appended claims. The scope.

Claims

An array tunable optical attenuator comprising at least one channel unit, the channel unit comprising at least two mutually independent modulated optical waveguides and a heating electrode disposed on the at least one modulated optical waveguide; characterized in that The input optical waveguide and/or the output optical waveguide to which the optical waveguide is connected have a curved portion that blocks light leakage to prevent light leakage from coupling with the modulated optical waveguide.
An array tunable optical attenuator according to claim 1, wherein each of the modulated optical waveguides is split on the same input optical waveguide and converges on the same output optical waveguide.
The array dimmable attenuator according to claim 1, wherein the heating electrode is connected to the electrode lead of the conductive function at both ends.
The array tunable optical attenuator according to claim 1, wherein the number of channel units is several, and a heat insulating slot is disposed between adjacent channel units.
The array dimmable attenuator according to claim 4, wherein the heat insulating groove is filled with a thermal conductivity of less than 0.026 W/(mk) and a thermal expansion coefficient of less than 0.5×10^-6/K. polymer.
The array dimmable attenuator according to claim 1, wherein the heating electrode has a resistivity of 50 to 500 nΩ·m; and/or an electrical conductivity of the electrode lead connected to the heating electrode. 60 to 110% IACS.
The array dimmable attenuator according to claim 1, wherein the heating electrode is provided with a metal film anti-oxidation protection layer.
An array dimming attenuation method, comprising:

Integrating the optical signal from the input curved optical waveguide into the attenuator and dividing the optical signal into at least two transmission optical paths;

The curved portion of the input optical waveguide and/or the output optical waveguide blocks light leakage of the input optical waveguide and/or the output optical waveguide to prevent leakage of light from coupling with the modulated optical waveguide;

Heating at least one transmission optical path to change a phase of the optical signal of the optical path;

The optical signals of the respective transmission optical paths are superimposed to achieve attenuation of the optical signal.
A method for fabricating an array of tunable optical attenuators, comprising:

Forming a silicon dioxide undercladding layer on the substrate, depositing a waveguide core layer on the lower cladding layer;

Etching the optical path of the dimmable optical attenuator array on the waveguide chip;

Depositing a silicon dioxide over cladding layer encasing the waveguide chip, and forming a heating electrode layer adjacent to the waveguide core layer on the upper cladding layer;

Wherein, when etching the optical path of the tunable optical attenuator array, the input optical waveguide and/or the output optical waveguide having a curved portion that blocks light leakage to prevent light leakage from coupling with the modulated optical waveguide is etched.
The method of fabricating an array tunable optical attenuator according to claim 9, comprising:

A heat insulating groove is etched between the channels, and the porous material is filled in the heat insulating groove;

and / or

A metal thin film anti-oxidation protective layer covering the heating electrode layer is formed on the upper cladding layer.