CN219163407U - Integrated waveguide type detector and photon integrated chip - Google Patents

Abstract

The application provides an integrated waveguide type detector and a photon integrated chip, and relates to the technical field of monolithic photon integration. The integrated waveguide type detector comprises a first lithium niobate thin film optical waveguide, two passivation layers, a graphene layer and a detection electrode. The passivation layers are made of silicon dioxide, are arranged at intervals along the first direction and are respectively connected with two opposite sides of the first lithium niobate thin film optical waveguide. The graphene layer and the first lithium niobate thin film optical waveguide are stacked along the second direction, the first direction is perpendicular to the second direction, and the graphene layer simultaneously covers at least part of the surfaces of the two passivation layers and at least part of the surface of the first lithium niobate thin film optical waveguide. The detection electrode is connected to the surface of the graphene layer, which is far away from the first lithium niobate thin film optical waveguide. According to the application, the first lithium niobate thin film optical waveguide is combined with the graphene layer, the transverse light absorption length can be increased through waveguide coupling, ultra-wideband, high responsivity and high-speed detection of light can be realized, and monolithic integration of the detector is realized.

Description

Integrated waveguide type detector and photon integrated chip

Technical Field

The application relates to the technical field of monolithic photon integration, in particular to an integrated waveguide type detector and a photon integrated chip.

Background

Optical communication technology is the mainstream technology of current communication by virtue of its advantages of high bandwidth, low crosstalk, low loss, interference resistance, etc. With the development of semiconductor photoelectronic technology, the integration and the chip formation of a photon device become the necessary trend of the development of optical communication technology, and the chip integration can not only greatly reduce the volume and the power consumption of a system, but also reduce the insertion loss of the device and reduce the packaging cost.

The photodetector is an indispensable element in an optoelectronic integrated circuit (Optoelectronic Integrated Circuit, OEIC) and can complete photoelectric conversion functions in an optical communication and optical interconnection system to realize conversion of data from an optical domain to an electrical domain. The waveguide type detector can avoid the problem of mutual restriction between the speed and the quantum efficiency of the optical detector, can be integrated with a waveguide light path, is easier to realize high-speed and high-responsiveness, and is one of core devices for realizing high-speed optical communication and optical interconnection chips.

However, since the conventional photodetector uses a compound material such as indium phosphide, the lattice mismatch problem exists when the compound material is combined with other materials, so that high-performance integration is difficult to realize, and ultra-wideband, high-responsiveness and high-speed detection of light cannot be effectively realized by the photodetector.

Disclosure of Invention

The purpose of the application is to provide an integrated waveguide type detector and a photon integrated chip, which aim to improve the technical problems that the photoelectric detector cannot effectively realize ultra-wideband, high responsivity and high-speed detection of light.

In a first aspect, embodiments of the present application provide an integrated waveguide detector, including: the device comprises a first lithium niobate thin film optical waveguide, a passivation layer, a graphene layer and a detection electrode.

The passivation layers are made of silicon dioxide, and the number of the passivation layers is two; the two passivation layers are arranged at intervals along the first direction and are respectively connected with two opposite sides of the first lithium niobate thin film optical waveguide.

The graphene layer and the first lithium niobate thin film optical waveguide are stacked along the second direction, the first direction is perpendicular to the second direction, and the graphene layer simultaneously covers at least part of the surfaces of the two passivation layers and at least part of the surface of the first lithium niobate thin film optical waveguide.

The detection electrode is connected to the surface of the graphene layer, which is far away from the first lithium niobate thin film optical waveguide.

In the technical scheme, the lithium niobate thin film material has excellent electro-optic characteristics and low-loss characteristics, the graphene material has excellent photoelectron characteristics such as broadband light response, intensity interaction with light, ultra-fast carrier migration rate and the like, and graphene can be integrated through intermolecular forces without considering lattice matching problems in the conventional bulk material combination; according to the method, passivation layers made of silicon dioxide are respectively connected with two opposite sides of the first lithium niobate thin film optical waveguide, so that passivation effect is achieved; the graphene layer and the first lithium niobate thin film optical waveguide are stacked, the first lithium niobate thin film optical waveguide is combined with the graphene layer, and the transverse light absorption length can be increased through waveguide coupling, so that the problem of low single-layer graphene absorption rate can be solved, ultra-wideband, high-responsiveness and high-speed detection of light can be realized, and monolithic integration of the detector is realized.

With reference to the first aspect, in an alternative embodiment of the present application, the first lithium niobate thin film optical waveguide includes: a first tapered waveguide and a first straight waveguide connected to each other in a third direction; the third direction is perpendicular to both the first direction and the second direction.

The two passivation layers are respectively connected with two opposite sides of the first straight waveguide, and the graphene layer covers at least part of the surfaces of the two passivation layers and at least part of the surfaces of the first straight waveguide at the same time.

When the photonic integrated chip is used, the first conical waveguide is used for being connected with the modulator in the photonic integrated chip, and the arrangement mode can reduce the coupling loss between the modulator and the first lithium niobate thin film optical waveguide.

With reference to the first aspect, in an alternative embodiment of the present application, the length direction of the first tapered waveguide and the length direction of the first straight waveguide are both parallel to the third direction.

With reference to the first aspect, in an alternative embodiment of the present application, the width of the first tapered waveguide gradually decreases along a direction in which the first tapered waveguide points to the first straight waveguide.

In the technical scheme, the coupling loss between the modulator and the first lithium niobate thin film optical waveguide is further reduced.

In combination with the first aspect, in an alternative embodiment of the present application, in the second direction, the dimensions of both passivation layers are equal to the dimensions of the first straight waveguide.

In the technical scheme, the connection stability between the graphene layer and the first straight waveguide and between the graphene layer and the two passivation layers can be improved, and the structural stability of the whole integrated waveguide type detector can be improved.

In combination with the first aspect, in an optional embodiment of the present application, the integrated waveguide detector further includes a second lithium niobate thin film optical waveguide of a slab structure, the second lithium niobate thin film optical waveguide is simultaneously connected with the first tapered waveguide, the first straight waveguide, and surfaces of the two passivation layers away from the graphene layer, and the first straight waveguide and the second lithium niobate thin film optical waveguide form a ridge structure.

In the technical scheme, the first straight waveguide and the second lithium niobate thin film optical waveguide form a ridge structure, so that the light can be limited, and the loss can be reduced.

In combination with the first aspect, in an alternative embodiment of the present application, the number of the detection electrodes is two, and the two detection electrodes are disposed on two opposite sides of the first lithium niobate thin film optical waveguide at intervals along the first direction.

In combination with the first aspect, in an optional embodiment of the present application, the detection electrode includes a titanium layer and a gold layer that are connected to each other, the titanium layer is connected to the graphene layer, and the gold layer is disposed on a side of the titanium layer away from the graphene layer.

Among the above-mentioned technical scheme, the detection electrode includes interconnect's titanium layer and gold layer, and wherein titanium layer is connected with the graphene layer, is favorable to improving the adhesion between detection electrode and the graphene layer, and then is favorable to improving the structural stability of whole integrated waveguide type detector. The arrangement of the gold layer is beneficial to improving the conductivity of the detection electrode.

In a second aspect, the present application provides a photonic integrated chip comprising: the spot-size converter, modulator and integrated waveguide detector provided in the first aspect are connected in sequence.

In the technical scheme, the lithium niobate thin film optical waveguide is combined with the graphene layer in the integrated waveguide type detector, so that the transverse light absorption length can be increased through waveguide coupling, the problem of low single-layer graphene absorption rate can be solved, ultra-wideband, high-responsivity and high-speed detection of light can be realized, and the monolithic integration of the detector is realized; therefore, the reliability and the stability of the whole photon integrated chip are improved, and the ultra-high speed transmission requirement of the photon integrated chip is met.

With reference to the first aspect, in an alternative embodiment of the present application, the photonic integrated chip further includes a substrate, where the substrate includes a silicon base layer and a silicon dioxide layer stacked along the second direction.

The mode spot converter, the modulator and the integrated waveguide type detector are all connected with the silicon dioxide layer, and the silicon substrate is positioned on one side of the silicon dioxide layer, which is far away from the mode spot converter, the modulator and the integrated waveguide type detector.

In the technical scheme, the spot-size converter, the modulator and the integrated waveguide type detector are all connected with the silicon dioxide layer, namely, the spot-size converter, the modulator and the integrated waveguide type detector are integrated on the same substrate at the same time, so that the volume, the power consumption and the packaging cost of the photon integrated chip can be greatly reduced.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are needed in the embodiments will be briefly described below, it being understood that the following drawings only illustrate some embodiments of the present application and therefore should not be considered limiting the scope, and that other related drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.

Fig. 1 is a top view of a first example of a photonic integrated chip provided in an embodiment of the present application.

Fig. 2 is a front view of a first example of a photonic integrated chip provided in an embodiment of the present application.

Fig. 3 is a top view of a second example of a photonic integrated chip provided in an embodiment of the present application.

Fig. 4 is a front view of a second example of a photonic integrated chip provided in an embodiment of the present application.

Fig. 5 is a top view of an integrated waveguide type detector provided in an embodiment of the present application.

Fig. 6 is a cross-sectional view taken along A-A in fig. 5.

Icon: 10-photon integrated chips; 101-a first direction; 102-a second direction; 103-third direction; a 100-mode spot-size converter; 110-fourth lithium niobate thin film optical waveguide; 111-a second tapered waveguide; 112-a third tapered waveguide; a 200-modulator; 210-a third lithium niobate thin film optical waveguide; 211-a first Y-branched waveguide; 212-a second straight waveguide; 213-a second Y-branch waveguide; 214-a first slab waveguide; 215-coupling a straight waveguide; 216-annular waveguide; 217-a second slab waveguide; 220-modulating electrodes; 300-an integrated waveguide detector; 310-a first lithium niobate thin film optical waveguide; 311-a first tapered waveguide; 312-a first straight waveguide; 320-a passivation layer; 330-graphene layer; 340-detecting electrodes; 350-a second lithium niobate thin film optical waveguide; 400-substrate; 410-a silicon-based layer; 420-silicon dioxide layer.

Detailed Description

Embodiments of the technical solutions of the present application will be described in detail below with reference to the accompanying drawings. The following examples are only for more clearly illustrating the technical solutions of the present application, and thus are only examples, and are not intended to limit the scope of protection of the present application.

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 to which this application belongs; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application; the term "comprising" in the description of the present application and in the description of the figures above, as well as any variants thereof, is intended to cover a non-exclusive inclusion.

In the description of the embodiments of the present application, the technical terms "first," "second," etc. are used merely to distinguish between different objects and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated, a particular order or a primary or secondary relationship.

Reference herein to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment may be included in at least one embodiment of the present application. The appearances of such phrases in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments. Those of skill in the art will explicitly and implicitly appreciate that the embodiments described herein may be combined with other embodiments.

In the description of the embodiments of the present application, the orientation or positional relationship indicated by the technical terms "length", "width", "thickness", "upper", etc. are based on the orientation or positional relationship shown in the drawings, and are merely for convenience of describing the embodiments of the present application and simplifying the description, rather than indicating or implying that the apparatus or element in question must have a specific orientation, be configured and operated in a specific orientation, and thus should not be construed as limiting the embodiments of the present application.

In the description of the embodiments of the present application, unless explicitly specified and limited otherwise, the term "coupled" is to be construed broadly, and may be, for example, fixedly coupled, detachably coupled, or integrally formed; or may be a mechanical connection; can be directly connected or indirectly connected through an intermediate medium, and can be communicated with the inside of two elements or the interaction relationship of the two elements. The specific meaning of the above terms in the embodiments of the present application will be understood by those of ordinary skill in the art according to the specific circumstances.

The present application provides a photonic integrated chip 10, fig. 1 is a top view of a first example of the photonic integrated chip 10 provided in the embodiment of the present application, fig. 2 is a front view of the first example of the photonic integrated chip 10 provided in the embodiment of the present application, fig. 3 is a top view of a second example of the photonic integrated chip 10 provided in the embodiment of the present application, fig. 4 is a front view of the second example of the photonic integrated chip 10 provided in the embodiment of the present application, please refer to fig. 1 to 4, and the photonic integrated chip 10 includes a spot-size converter 100, a modulator 200, and an integrated waveguide detector 300 connected in sequence.

The spot-size converter 100 is used as an optical signal input terminal for receiving an optical signal and transmitting the optical signal to the modulator 200; the modulator 200 is configured to modulate the optical signal transmitted by the spot-size converter 100, and transmit the modulated optical signal to the integrated waveguide detector 300; the integrated waveguide type detector 300 is used for photoelectrically converting the optical signal modulated by the modulator 200.

The photonic integrated chip 10 further includes a substrate 400, and the spot-size converter 100, the modulator 200, and the integrated waveguide-type detector 300 are disposed on the same side of the substrate 400 and connected to the substrate 400. In the above arrangement, the spot-size converter 100, the modulator 200 and the integrated waveguide detector 300 are integrated on the same substrate 400 at the same time, so that the volume, the power consumption and the packaging cost of the photonic integrated chip 10 can be greatly reduced.

Fig. 5 is a top view of an integrated waveguide-type detector 300 according to an embodiment of the present application, and fig. 6 is a cross-sectional view along A-A in fig. 5. Referring to fig. 1 to 6, the integrated waveguide-type detector 300 includes a first lithium niobate thin film optical waveguide 310, a passivation layer 320, a graphene layer 330, and a detection electrode 340.

The passivation layer 320 is made of silicon dioxide, and the number of the passivation layers 320 is two; the two passivation layers 320 are spaced apart along the first direction 101 and are respectively connected to opposite sides of the first lithium niobate thin film optical waveguide 310. The passivation layer 320 made of silicon dioxide may perform passivation.

The graphene layer 330 and the first lithium niobate thin film optical waveguide 310 are stacked along the second direction 102, the first direction 101 is perpendicular to the second direction 102, and the graphene layer 330 covers at least part of the surfaces of the two passivation layers 320 and at least part of the surfaces of the first lithium niobate thin film optical waveguide 310 at the same time. The detection electrode 340 is connected to a surface of the graphene layer 330 remote from the first lithium niobate thin film optical waveguide 310.

The lithium niobate thin film material has excellent electro-optic characteristics and low loss characteristics; the graphene material has excellent photoelectron characteristics such as broadband light response, intensity interaction with light, ultra-fast carrier migration rate and the like, and can be integrated through intermolecular forces without considering the lattice matching problem in the traditional bulk material combination, and the graphene has the advantage of easy transfer integration as a two-dimensional material; according to the method, the graphene layer 330 and the first lithium niobate thin film optical waveguide 310 are stacked, the lithium niobate thin film material and the graphene material are combined, and the waveguide coupling is adopted, so that the transverse light absorption length can be increased, the problem of low single-layer graphene absorption rate can be solved, ultra-wideband, high-responsiveness and high-speed detection of light can be realized, and the monolithic integration and high integration level of the detector are realized; and further, the reliability and stability of the whole photonic integrated chip 10 are improved, and the ultra-high-speed transmission requirement of the photonic integrated chip 10 is met.

In the present application, the first lithium niobate thin film optical waveguide 310 includes a first tapered waveguide 311 and a first straight waveguide 312 connected to each other along the third direction 103; the third direction 103 is perpendicular to both the first direction 101 and the second direction 102. The two passivation layers 320 are respectively connected to opposite sides of the first straight waveguide 312, and the graphene layer 330 covers at least part of the surfaces of the two passivation layers 320 and at least part of the surface of the first straight waveguide 312 at the same time.

In use, the first tapered waveguide 311 is connected to the modulator 200 in the photonic integrated chip 10; the present application can reduce coupling loss between the modulator 200 and the first lithium niobate thin film optical waveguide 310 by disposing the first lithium niobate thin film optical waveguide 310 in the integrated waveguide type detector 300 as the first tapered waveguide 311 and the first straight waveguide 312 connected to each other in the third direction 103.

Further, in the present application, the length direction of the first tapered waveguide 311 and the length direction of the first straight waveguide 312 are both parallel to the third direction 103. Illustratively, in the present application, the first straight waveguide 312 has a dimension (i.e., width) in the first direction 101 of 0.8-1.0 μm; along the third direction 103, the first straight waveguide 312 has a dimension (i.e., length) of 0.8-1.0 μm; along the second direction 102, the first straight waveguides 312 each have a dimension (i.e., height) of 0.25-0.35 μm.

In the present application, the width of the first tapered waveguide 311 is gradually reduced along the direction in which the first tapered waveguide 311 points to the first straight waveguide 312, which is advantageous for further reducing the coupling loss between the modulator 200 and the first lithium niobate thin film optical waveguide 310.

As an example, the width of the first tapered waveguide 311 is gradually changed from 0.8 to 1.0 μm to 0.6 μm or less along the direction in which the first tapered waveguide 311 is directed toward the first straight waveguide 312; the first tapered waveguide 311 has a dimension (i.e., height) of 0.25 to 0.35 μm in the second direction 102; the first tapered waveguide 311 has a dimension (i.e., length) of 200 μm or more along the third direction 103.

Further, in the present application, the dimensions of both passivation layers 320 are equal to the dimensions of the first straight waveguide 312 along the second direction 102. By the arrangement, the connection stability between the graphene layer 330 and the first straight waveguide 312 and between the graphene layer and the passivation layers 320 can be improved, which is beneficial to improving the structural stability of the whole integrated waveguide type detector 300.

Illustratively, the dimensions of the two passivation layers 320 and the first straight waveguide 312 are each 0.25-0.35 μm along the second direction 102.

In this application, the integrated waveguide type detector 300 further includes a second lithium niobate thin film optical waveguide 350 having a slab structure, the second lithium niobate thin film optical waveguide 350 is simultaneously connected to the first tapered waveguide 311, the first straight waveguide 312, and the surfaces of the two passivation layers 320 away from the graphene layer 330, and the first straight waveguide 312 and the second lithium niobate thin film optical waveguide 350 form a ridge structure. The second lithium niobate thin film optical waveguide 350 is coupled to the substrate 400.

In the above arrangement, the first straight waveguide 312 and the second lithium niobate thin film optical waveguide 350 form a ridge structure, which can limit light, and is beneficial to reducing loss.

As an example, the second lithium niobate thin film optical waveguide 350 has a size of 0.25 to 0.35 μm along the second direction 102.

Illustratively, in the present application, the graphene layer 330 has a dimension in the second direction 102 of 0.3-20 nm.

In the present application, the detection electrode 340 is connected to the surface of the graphene layer 330 away from the first lithium niobate thin film optical waveguide 310; the number of the detection electrodes 340 is two, and the two detection electrodes 340 are disposed at opposite sides of the first lithium niobate thin film optical waveguide 310 at intervals along the first direction 101.

Further, each of the detection electrodes 340 includes a titanium layer (not shown) and a gold layer (not shown) that are connected to each other, the titanium layer is connected to the graphene layer 330, and the gold layer is disposed on a side of the titanium layer away from the graphene layer 330.

In the above arrangement, the titanium layer is connected with the graphene layer 330, which is favorable for improving the adhesiveness between the detection electrode 340 and the graphene layer 330, and further is favorable for improving the structural stability of the whole integrated waveguide type detector 300. The provision of the gold layer is advantageous in improving the conductivity of the detection electrode 340.

Illustratively, the probe electrode 340 is configured as a metallic CPW traveling wave electrode; in the probe electrode 340, the thickness of the titanium layer is 50 to 100nm, and the thickness of the gold layer is 800 to 1000nm.

Referring again to fig. 1-4, the modulator 200 includes a third lithium niobate thin film optical waveguide 210 and a modulating electrode 220. The modulator electrode 220 is disposed on opposite sides of the third lithium niobate thin film optical waveguide 210 along the first direction 101. The modulator 200 of the present utility model can produce an electro-optical modulator 200 with high efficiency and high speed by utilizing the excellent electro-optical characteristics and loss characteristics of the lithium niobate thin film material.

In the first example shown in fig. 1 and 2, the third lithium niobate thin film optical waveguide 210 is a mach-zehnder interferometer (MZ), which is advantageous in that the operating wavelength range is wide.

In the first example shown in fig. 1 and 2, the third lithium niobate thin film optical waveguide 210 includes one first Y-branch waveguide 211, two second straight waveguides 212, and one second Y-branch waveguide 213; the two second straight waveguides 212 are arranged at intervals along the first direction 101, the first Y-branch waveguide 211 and the second Y-branch waveguide 213 are respectively arranged at two opposite sides of the second straight waveguide 212 along the third direction 103, and the first Y-branch waveguide 211, the second straight waveguide 212 and the second Y-branch waveguide 213 are sequentially connected along the direction of the modulator 200 pointing to the integrated waveguide type detector 300; one end of the second Y-branch waveguide 213, which is far from the second straight waveguide 212, is connected to the first lithium niobate thin film optical waveguide 310 in the integrated waveguide type probe 300; the modulating electrodes 220 are disposed on opposite sides of the second straight waveguide 212 along the first direction 101.

Further, in the first example shown in fig. 1 and 2, the third lithium niobate thin film optical waveguide 210 further includes a first slab waveguide 214, the first slab waveguide 214 is connected to the substrate 400, and the first Y-branch waveguide 211, the second straight waveguide 212, and the second Y-branch waveguide 213 are all connected to a surface of the first slab waveguide 214 away from the substrate 400, and the first slab waveguide 214 is connected to the second lithium niobate thin film optical waveguide 350.

Still further, in the first example shown in fig. 1 and 2, the third lithium niobate thin film optical waveguide 210 has a ridge structure, the first slab waveguide 214 is a slab portion of the ridge structure, and the first Y-branch waveguide 211, the second straight waveguide 212, and the second Y-branch waveguide 213 are ridges of the ridge structure. The third lithium niobate thin film optical waveguide 210 has a ridge structure, which can limit light, and is beneficial to reducing loss.

As an example, the dimensions of the first Y-branch waveguide 211, the second straight waveguide 212, the second Y-branch waveguide 213, and the first slab waveguide 214 are all 0.25 to 0.35 μm along the second direction 102; the dimensions of the first Y-branch waveguide 211, the second straight waveguide 212, and the second Y-branch waveguide 213 are all 0.8 to 1 μm along the first direction 101.

The third lithium niobate thin film optical waveguide 210 may be disposed in other manners, for example, in the second example shown in fig. 3 and 4, the third lithium niobate thin film optical waveguide 210 is a micro-ring resonator, which is advantageous in that the size is small and the frequency is high.

In the second example shown in fig. 3 and 4, the third lithium niobate thin film optical waveguide 210 includes a coupling straight waveguide 215 and an annular waveguide 216, the annular waveguide 216 being disposed on one side of the coupling straight waveguide 215 in the first direction 101. The coupling straight waveguide 215 is connected with a first lithium niobate thin film optical waveguide 310 in the integrated waveguide type detector 300; the modulating electrodes 220 are disposed along the first direction 101 on opposite sides of the annular waveguide 216 along the first direction 101.

Further, in the second example shown in fig. 3 and 4, the third lithium niobate thin film optical waveguide 210 further includes a second slab waveguide 217, the second slab waveguide 217 is connected to the substrate 400, and the coupling straight waveguide 215 and the ring waveguide 216 are both connected to a surface of the second slab waveguide 217 remote from the substrate 400, and the second slab waveguide 217 is connected to the second lithium niobate thin film optical waveguide 350.

Still further, in the second example shown in fig. 3 and 4, the third lithium niobate thin film optical waveguide 210 has a ridge structure, the second slab waveguide 217 is a slab portion of the ridge structure, and the coupling straight waveguide 215 and the annular waveguide 216 are ridges of the ridge structure. The third lithium niobate thin film optical waveguide 210 has a ridge structure, which can limit light, and is beneficial to reducing loss.

As an example, the dimensions of the second slab waveguide 217, the coupling straight waveguide 215, and the annular waveguide 216 are all 0.25 to 0.35 μm along the second direction 102; along the first direction 101, the dimensions of the coupling straight waveguides 215 are all 0.8-1 μm; the annular waveguide 216 has a width (i.e., the difference between the outer radius and the inner radius) of 0.8-1 μm.

In the present application, the modulating electrode 220 includes a titanium layer (not shown) and a gold layer (not shown) connected to each other. In the above arrangement, the titanium layer is connected to the first slab waveguide 214 (or the second slab waveguide 217), which is beneficial to improving the adhesion between the modulating electrode 220 and the first slab waveguide 214 (or the second slab waveguide 217), and further beneficial to improving the structural stability of the whole modulator 200. The provision of the gold layer is advantageous in improving the conductivity of the modulating electrode 220.

Illustratively, the modulating electrode 220 is configured as a metallic CPW traveling wave electrode; in the modulating electrode 220, the thickness of the titanium layer is 50 to 100nm, and the thickness of the gold layer is 800 to 1000nm.

Referring again to fig. 1 to 4, the spot-size converter 100 includes a fourth lithium niobate thin film optical waveguide 110, the fourth lithium niobate thin film optical waveguide 110 including a second tapered waveguide 111 and a third tapered waveguide 112 stacked along the second direction 102, each of the second tapered waveguide 111 and the third tapered waveguide 112 being connected to a third lithium niobate thin film optical waveguide 210.

In the present application, the length direction of the second tapered waveguide 111 and the length direction of the third tapered waveguide 112 are parallel to the third direction 103, and the widths of the second tapered waveguide 111 and the third tapered waveguide 112 gradually increase along the direction in which the fourth lithium niobate thin film optical waveguide 110 points to the third lithium niobate thin film optical waveguide 210; that is, the fourth lithium niobate thin film optical waveguide 110 of the present application has a double inverted taper waveguide structure.

The fourth lithium niobate thin film optical waveguide 110 is configured as a double inverted cone waveguide structure, and can be used for realizing mode transition and matching between an incident optical mode field and the lithium niobate thin film optical waveguide, and improving optical coupling efficiency.

In this application, the second tapered waveguide 111 and the third tapered waveguide 112 are disposed close to one end of the third lithium niobate thin film optical waveguide 210 in an aligned manner, so that both the second tapered waveguide 111 and the third tapered waveguide 112 can be ensured to be effectively connected to the third lithium niobate thin film optical waveguide 210 of the modulator 200.

Further, in the present application, the second tapered waveguide 111 and the third tapered waveguide 112 form a ridge structure, the second tapered waveguide 111 is a slab structure, and the third tapered waveguide 112 serves as a ridge of the ridge structure; the arrangement mode can limit light, and is beneficial to reducing loss.

As an example, the second tapered waveguide 111 has a dimension (i.e., length) of 200 μm or more (e.g., 450 to 550 μm) along the third direction 103; along the direction in which the fourth lithium niobate thin film optical waveguide 110 points to the third lithium niobate thin film optical waveguide 210, the width of the second tapered waveguide 111 is gradually changed from 0.3 μm to 1 μm; the second tapered waveguide 111 has a dimension (i.e., height) of 0.25 to 0.35 μm in the second direction 102.

As an example, along the third direction 103, the third tapered waveguide 112 has a dimension (i.e., length) of 50 μm or more (e.g., 250-350 μm); along the direction that the fourth lithium niobate thin film optical waveguide 110 points to the third lithium niobate thin film optical waveguide 210, the width of the third tapered waveguide 112 is gradually changed from 0.3 μm to 0.8 to 1 μm; the third tapered waveguide 112 has a dimension (i.e., height) of 0.25 to 0.35 μm in the second direction 102.

The spot-size converter 100, modulator 200 and integrated waveguide detector 300 are simultaneously integrated on the same substrate 400. In this application, the substrate 400 includes a silicon-based layer 410 and a silicon dioxide layer 420 stacked along the second direction 102. The spot-size converter 100, modulator 200 and integrated waveguide detector 300 are all connected to the silicon dioxide layer 420, and the silicon substrate 410 is located on the side of the silicon dioxide layer 420 remote from the spot-size converter 100, modulator 200 and integrated waveguide detector 300. Wherein the silicon dioxide layer 420 primarily serves passivation and the silicon-based layer 410 primarily serves support.

Further, in the present application, the size (i.e., thickness) of the silicon oxide layer 420 is 1 μm or more in the second direction 102. Within the above parameters, it may be advantageous to ensure the performance of the modulator 200; if the size of the silicon dioxide layer 420 is too thin in the second direction 102, the passivation effect is affected.

Still further, the dimension (i.e., thickness) of the silicon dioxide layer 420 is 3-6 μm along the second direction 102. Within the above parameters, it may be advantageous to further ensure the performance of the modulator 200;

illustratively, in the present application, the silicon-based layer 410 has a dimension (i.e., thickness) in the second direction 102 of 450-550 μm.

The present embodiment further provides an integrated waveguide-type probe 300, and the structure, shape and connection manner of the integrated waveguide-type probe 300 are described above, and are not repeated here.

The integrated waveguide type detector 300 provided by the application stacks the graphene layer 330 and the first lithium niobate thin film optical waveguide 310, combines the lithium niobate thin film material with the graphene material, and can increase the transverse light absorption length through waveguide coupling, so that the problem of low single-layer graphene absorptivity can be solved, ultra-wideband, high responsivity and high-speed detection of light can be realized, and the monolithic integration and high integration level of the detector are realized.

The foregoing description is only of the preferred embodiments of the present application and is not intended to limit the same, but rather, various modifications and variations may be made by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims (10)

1. An integrated waveguide detector, comprising: the device comprises a first lithium niobate thin film optical waveguide, a passivation layer, a graphene layer and a detection electrode;

the passivation layers are made of silicon dioxide, and the number of the passivation layers is two; the two passivation layers are arranged at intervals along the first direction and are respectively connected with the two opposite sides of the first lithium niobate thin film optical waveguide;

the graphene layers and the first lithium niobate thin film optical waveguides are stacked along a second direction, the first direction is perpendicular to the second direction, and the graphene layers simultaneously cover at least part of the surfaces of the passivation layers and at least part of the surfaces of the first lithium niobate thin film optical waveguides;

the detection electrode is connected to the surface, far away from the first lithium niobate thin film optical waveguide, of the graphene layer.

2. The integrated waveguide detector of claim 1, wherein the first lithium niobate thin film optical waveguide comprises: a first tapered waveguide and a first straight waveguide connected to each other in a third direction; the third direction is perpendicular to both the first direction and the second direction;

the two passivation layers are respectively connected with two opposite sides of the first straight waveguide, and the graphene layers cover at least part of the surfaces of the two passivation layers and at least part of the surfaces of the first straight waveguide at the same time.

3. The integrated waveguide detector of claim 2, wherein a length direction of the first tapered waveguide and a length direction of the first straight waveguide are both parallel to the third direction.

4. The integrated waveguide detector of claim 3, wherein the width of the first tapered waveguide tapers in a direction in which the first tapered waveguide points toward the first straight waveguide.

5. The integrated waveguide detector of claim 2, wherein in the second direction, both of the passivation layers are equal in size to the first straight waveguide.

6. The integrated waveguide detector of any of claims 2-5, further comprising a second lithium niobate thin film optical waveguide of slab structure connected simultaneously with the first tapered waveguide, the first straight waveguide, and the surfaces of the two passivation layers remote from the graphene layer, and the first straight waveguide and the second lithium niobate thin film optical waveguide forming a ridge structure.

7. The integrated waveguide detector of claim 1, wherein the number of detection electrodes is two, and two of the detection electrodes are disposed on opposite sides of the first lithium niobate thin film optical waveguide at intervals along the first direction.

8. The integrated waveguide detector of claim 7, wherein the detection electrode comprises a titanium layer and a gold layer that are connected to each other, the titanium layer being connected to the graphene layer, the gold layer being disposed on a side of the titanium layer that is remote from the graphene layer.

9. A photonic integrated chip, comprising: a spot-size converter, a modulator and an integrated waveguide detector according to any of claims 1-8, connected in sequence.

10. The photonic integrated chip of claim 9, further comprising a substrate comprising a silicon-based layer and a silicon dioxide layer stacked along the second direction;

the spot-size converter, the modulator and the integrated waveguide detector are all connected with the silicon dioxide layer, and the silicon base layer is positioned on one side of the silicon dioxide layer far away from the spot-size converter, the modulator and the integrated waveguide detector.

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