Pre-amplified optical detector and preparation method thereof, and photoelectric detection device

Abstract

The application discloses a pre-amplification optical detector and a preparation method thereof, and an optoelectronic detection device, wherein the pre-amplification optical detector comprises a substrate, an amplification region, a passive region and a detection region which are sequentially adjacent; an optical amplification module is arranged on the amplification region of the substrate and is used for enhancing the power of an optical signal and comprises a first core layer; a passive waveguide is arranged on the passive region and the detection region of the substrate and comprises a second core layer; the optical signal after power enhancement is coupled from the first core layer to the second core layer of the passive waveguide; and a waveguide detector is arranged on the passive waveguide of the detection region; the optical signal enters the waveguide detector from the second core layer in an evanescent wave coupling mode; and the side surface of the first core layer is connected with the side surface of the second core layer. The device is integrated on the substrate by using a monolithic integration technology, the sensitivity of the optical detector is improved, and the end surface contact between the devices is used to realize optical signal transmission, so that the coupling loss of the optical signal caused by the use of optical fiber transmission is avoided.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of optoelectronic devices, and particularly relates to a pre-amplification optical detector, a preparation method thereof and an optoelectronic detection device. BACKGROUND

[0002] The increasing network data traffic year by year puts forward increasingly stringent requirements on the carrying capacity of optical communication networks, which in turn promotes the development of optical information transmission networks in the direction of rapidity and high capacity. For example, the symbol rate of long-haul and medium-short-haul optical transmission links (such as the IEEE P802.3bs standard) will be increased to 56GBd and 64GBd, respectively. If the direct modulation format is maintained, the device cost of the transmitting end and the receiving end can be greatly reduced. By using pre-amplification at the receiving end, the power consumption of the transmitting end in the direct modulation format can be reduced, which helps to improve the performance of the laser.

[0003] The combination of the prior art optical fiber amplifier and the waveguide detector is a discrete device, which is costly, has large optical coupling loss and poor stability; the combination of the detector and the trans-impedance amplifier (TIA) will cause the sensitivity of the light to decrease at high transmission rates. SUMMARY

[0004] Therefore, the main purpose of the present application is to provide a pre-amplification optical detector, a preparation method thereof and an optoelectronic detection device, so as to at least partially solve at least one of the above technical problems.

[0005] To achieve the above-mentioned purpose, as one aspect of the present application, a pre-amplification optical detector is disclosed, comprising:

[0006] a substrate comprising an amplification region, a passive region and a detection region which are sequentially adjacent;

[0007] an optical amplification module arranged on the amplification region of the substrate, for enhancing the power of the optical signal, and comprising a first core layer;

[0008] a passive waveguide arranged on the passive region and the detection region of the substrate, and comprising a second core layer; the power-enhanced optical signal is coupled from the first core layer to the second core layer of the passive waveguide; and

[0009] a waveguide detector arranged on the passive waveguide of the detection region; the optical signal enters the waveguide detector from the second core layer in an evanescent wave coupling manner, and is converted into an electrical signal by the waveguide detector;

[0010] wherein the side surface of the first core layer is connected with the side surface of the second core layer, so as to improve the coupling efficiency of the optical signal.

[0011] As another aspect of the present application, a method for manufacturing the pre-amplified optical detector is also disclosed, comprising:

[0012] S1: preparing an optical amplification module on a substrate, the optical amplification module being located on an amplification region of the substrate;

[0013] S2: preparing a passive waveguide on the substrate on a side of the optical amplification module obtained in step S1, the passive waveguide being located on a passive region and a detection region of the substrate;

[0014] S3: preparing a waveguide detector on the passive waveguide located on the detection region, to obtain the pre-amplified optical detector.

[0015] As another aspect of the present application, a photoelectric detection device is also disclosed, comprising:

[0016] the pre-amplified optical detector as described above; and

[0017] a waveguide section arranged on the substrate, comprising:

[0018] a first end face having an included angle of 7° with an output end face of an optical fiber;

[0019] a second end face coupled to the optical amplification module of the optical detector; and

[0020] a bending portion located between the first end face and the second end face.

[0021] Based on the above technical solution, the pre-amplified optical detector and the method for manufacturing the same, and the photoelectric detection device have at least one of the following advantages over the prior art:

[0022] 1. In the present application, the pre-amplified optical detector uses monolithic integrated technology to integrate the optical amplification module, the passive waveguide, and the waveguide detector on the same substrate, and the gain effect of the optical amplification module on the optical signal improves the sensitivity of the pre-amplified optical detector. In the optical detector, the optical signal is transmitted through the end face contact between the devices, thereby avoiding the coupling loss of the optical signal caused by the use of optical fibers for transmitting the optical signal when the discrete devices are interconnected.

[0023] 2. In the pre-amplified optical detector of the present application, the evanescent wave coupling effect of the optical signal is used to realize the transmission of the optical signal from the passive waveguide to the waveguide detector, which improves the coupling efficiency of the optical signal transmission to the waveguide detector and improves the bandwidth of the detector.

[0024] 3. In the pre-amplified optical detector of the present application, different types of optical amplification modules or different types of waveguide detectors can be used, or the thickness of each layer of the waveguide detector can be adjusted to achieve different performances and meet different requirements. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1A is a perspective structural schematic diagram of a pre-amplification optical detector in an embodiment of the present application;

[0026] Figure 1B is a cross-sectional structural schematic diagram of a pre-amplification optical detector in an embodiment of the present application;

[0027] Figure 2 is a schematic diagram of a photoelectric detection device structure in an embodiment of the present application;

[0028] Figure 3 is a schematic diagram of a structure formed in step A in a preparation method of a pre-amplification optical detector in an embodiment of the present application;

[0029] Figure 4 is a schematic diagram of a structure formed in step D in a preparation method of a pre-amplification optical detector in an embodiment of the present application;

[0030] Figure 5 is a schematic diagram of a structure formed in step G in a preparation method of a pre-amplification optical detector in an embodiment of the present application.

[0031] BRIEF DESCRIPTION OF DRAWINGS

[0032] 100 - substrate;

[0033] 200 - optical amplification module;

[0034] 21 - first N-type contact layer; 22 - first core layer; 23 - first cladding layer;

[0035] 24 - first P-type contact layer;

[0036] 300 - passive waveguide;

[0037] 31 - second cladding layer; 32 - second core layer;

[0038] 321 - first sub-core layer; 322 - second sub-core layer; 3221 - sub-core layer transmission section;

[0039] 400 - waveguide detector;

[0040] 41 - second N-type contact layer; 42 - absorption layer; 43 - third cladding layer; 44 - second P-type contact layer;

[0041] 5 - waveguide section. DETAILED DESCRIPTION

[0042] In order to make the objectives, technical solutions and advantages of the present application clearer, further detailed description will be made to the present application with reference to specific embodiments and the accompanying drawings.

[0043] Photonics integrated chip (PIC) is a technology of integrating a large number of functional photonic devices on the same substrate. Compared with discrete optical devices, PIC has the advantages of high coupling efficiency, low energy consumption, small size, low cost and high reliability. Therefore, the development of PIC has been paid great attention at home and abroad. The waveguide detector with pre-amplification realized by PIC technology has the advantages of PIC, and also effectively avoids the shortcomings of traditional APD detectors that high bandwidth and high gain cannot be achieved at the same time, because of the separation of optical amplification function and detection function. As described above, the pre-amplified optical detector is very suitable for use as a core device in a receiver to reduce the power consumption of the transmitting end and simplify the equipment complexity of the link. The pre-amplified detector provides a good technical route for realizing low-cost, high-performance and high-reliability optical transmission network, and has a wide application prospect.

[0044] In the process of implementing the present application, it is found that the main structure of the device is constructed by semiconductor process, and the compatibility of the semiconductor optical amplifier and the waveguide detector epitaxial structure is realized by selective epitaxy technology. The end-to-end structure of the semiconductor optical amplifier and the passive waveguide can maximize the retention of the structure and excellent performance of the semiconductor optical amplifier, passive waveguide and detector, so that the pre-amplified optical detector has the advantages of high gain, high bandwidth and strong scalability.

[0045] The present application discloses a pre-amplified optical detector, comprising:

[0046] A substrate 100 comprises an amplification region, a passive region and a detection region which are sequentially adjacent;

[0047] An optical amplification module 200 is arranged on the amplification region of the substrate 100, and is used for enhancing the power of the optical signal, and comprises a first core layer 22;

[0048] A passive waveguide 300 is arranged on the passive region and the detection region of the substrate 100, and comprises a second core layer 32; the power-enhanced optical signal is coupled from the first core layer 22 to the second core layer 32 of the passive waveguide 300; and

[0049] A waveguide detector 400 is arranged on the passive waveguide 300 of the detection region; the optical signal enters the waveguide detector 400 from the second core layer 32 in the form of evanescent wave coupling, and is converted into an electrical signal by the waveguide detector 400;

[0050] The side surface of the first core layer 22 is connected with the side surface of the second core layer 32, so as to improve the coupling efficiency of the optical signal.

[0051] In some embodiments of the present application, the optical amplification module 200 further comprises:

[0052] A first N-type contact layer 21 is disposed on the substrate 100 and connected with a first surface of the first core layer 22;

[0053] A first cladding layer 23 is disposed on a second surface of the first core layer 22, the first surface being opposite to the second surface; and

[0054] A first P-type contact layer 24 is disposed on the first cladding layer 23.

[0055] In some embodiments of the present application, the passive waveguide 300 further comprises:

[0056] A second cladding layer 31 is disposed on the substrate 100 and connected with a first surface of the second core layer 32; the thickness of the second cladding layer 31 is 200-1000 nm.

[0057] In some embodiments of the present application, the second core layer 32 comprises a first sub-core layer 321 and a second sub-core layer 322 disposed on the first sub-core layer 321.

[0058] The second sub-core layer 322 comprises a sub-core layer transmission segment 3221 connected with the first core layer 22.

[0059] In some embodiments of the present application, the sub-core layer transmission segment 3221 and the first core layer 22 form an axial symmetric structure in the direction of light incidence, so as to improve the coupling efficiency of the light signal coupled from the first core layer 22 to the second core layer 32.

[0060] In some embodiments of the present application, the distance from the second surface of the first core layer 22 to the bottom of the substrate 100 is H1,

[0061] The distance from the second surface of the second core layer 32 to the bottom of the substrate 100 is H2; wherein H1

[0062] In some embodiments of the present application, the difference between H2 and H1 is 250-650 nm, for example, the difference between H2 and H1 can be 250 nm, 300 nm, 350 nm, 400 nm, 450 nm, 500 nm, 550 nm, 600 nm or 650 nm.

[0063] In some embodiments of the present application, the waveguide detector 400 comprises:

[0064] A second N-type contact layer 41 is disposed on the passive waveguide 300.

[0065] An absorption layer 42 is disposed on the second N-type contact layer 41.

[0066] A third cladding layer 43 is disposed on the absorption layer 42.

[0067] a second P-type contact layer 44 disposed on the third cladding layer 43;

[0068] In some embodiments of the present application, the distance between the second N-type contact layer 41 and the optical amplification module 200 is L1, the distance between the absorption layer 42, the third cladding layer 43 and the second P-type contact layer 44 and the optical amplification module 200 is L2, and L1 < L2, so as to improve the evanescent wave coupling efficiency of the optical signal;

[0069] In some embodiments of the present application, the difference between L2 and L1 is 1 to 10 μm;

[0070] For example, the difference between L2 and L1 can be 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm or 10 μm.

[0071] In some embodiments of the present application, the optical refractive index of the second N-type contact layer 41 is between the optical refractive index of the second core layer 32 and the optical refractive index of the absorption layer 42, so that the optical signal enters the absorption layer 42 through the second N-type contact layer 41 in an evanescent wave coupling manner.

[0072] In some embodiments of the present application, the material used by the second N-type contact layer 41 includes InGaAsP and InP;

[0073] In some embodiments of the present application, the material used by the absorption layer 42 includes InGaAs;

[0074] In some embodiments of the present application, the material used by the third cladding layer 43 includes P-type doped InGaAsP;

[0075] In some embodiments of the present application, the material used by the second P-type contact layer 44 includes InGaAs.

[0076] In some embodiments of the present application, the material used by the substrate 100 includes InP;

[0077] In some embodiments of the present application, the material used by the first core layer 22 includes undoped InGaAsP bulk material and InGaAsP multi-quantum well material;

[0078] In some embodiments of the present application, the material used by the second core layer 32 includes undoped InGaAsP material.

[0079] The present application also discloses a preparation method of the pre-amplified optical detector as described above, comprising:

[0080] S1: preparing an optical amplification module 200 on a substrate 100, the optical amplification module 200 being located on an amplification region on the substrate 100;

[0081] S2: preparing a passive waveguide 300 on the substrate 100 on one side of the optical amplification module 200 obtained in step S1, the passive waveguide 300 being located on a passive region and a detection region on the substrate 100;

[0082] S3: preparing a waveguide detector 400 on the passive waveguide 300 located on the detection region, to obtain the pre-amplified optical detector.

[0083] The application further discloses an optoelectronic detection device, comprising:

[0084] the pre-amplified optical detector as described above; and

[0085] a waveguide section 5 arranged on the substrate 100 and comprising:

[0086] a first end face forming a 7° angle with an output end face of an optical fiber;

[0087] a second end face coupled to the optical amplification module 200 of the optical detector; and

[0088] a bending part located between the first end face and the second end face.

[0089] In one embodiment of the application, a pre-amplified waveguide detector is disclosed, as shown in Figure 1A and Figure 1B comprises:

[0090] a substrate 100 comprising an amplification region, a passive region and a detection region in sequence;

[0091] a semiconductor optical amplifier (i.e., the optical amplification module 200) for amplifying signal light, arranged on the amplification region on the substrate 100, and comprising, from bottom to top, a first N-type contact layer 21, a first core layer 22, a first cladding layer 23 and a first P-type contact layer 24, wherein the first N-type contact layer 21 and the first P-type contact layer 24 are contact layers of different doping types;

[0092] a passive waveguide 300 arranged on the passive region and the detection region on the substrate 100, for receiving optical signals output by the semiconductor optical amplifier (i.e., the optical amplification module 200), and comprising, from bottom to top, a second cladding layer 31 and a second core layer 32; and

[0093] The waveguide detector 400 is arranged on the passive waveguide 300 in the detection region, and is used for detecting the optical signal. The waveguide detector 400 comprises, from bottom to top, a second N-type contact layer 41, an absorption layer 42, a third cladding layer 43 and a second P-type contact layer 44. The second N-type contact layer 41 and the second P-type contact layer 44 are contact layers of different doping types.

[0094] The width of the first cladding layer 23 and the first P-type contact layer 24 of the semiconductor optical amplifier (i.e., the optical amplification module 200) is less than the width of the first core layer 22. The end face of the second core layer 32 of the passive waveguide 300 is in mutual butt joint with the end face of the first core layer 22 of the semiconductor optical amplifier (i.e., the optical amplification module 200), so as to improve the optical coupling efficiency between the semiconductor optical amplifier (i.e., the optical amplification module 200) and the passive waveguide 300. The length L2 of the second N-type contact layer 41 of the waveguide detector 400 in horizontal projection is greater than the length L1 of the absorption layer 42 in horizontal projection, i.e., L1 < L2, so as to improve the optical absorption efficiency of the detector. Figure 1B The length L2 of the second N-type contact layer 41 of the waveguide detector 400 in horizontal projection is greater than the length L1 of the absorption layer 42 in horizontal projection, i.e., L1 < L2, so as to improve the optical absorption efficiency of the detector.

[0095] The following will be described in detail the various components of the optical detector with pre-amplification in the embodiment, as shown in Figure 1A Figure 1B

[0096] In the embodiment, the substrate 100 is a semi-insulating InP substrate. The layers on the substrate 100, including the first N-type contact layer 21, the SOA core layer 22, the first cladding layer 23 and the first P-type contact layer 24, are formed by epitaxial growth through a metal organic chemical vapor deposition (MOCVD) method.

[0097] In the embodiment, the first cladding layer 23 and the first P-type contact layer 24 are cuboid structures, the width of which in horizontal projection is 2-3 μm, and the sum of the depths of the first cladding layer 23 and the first P-type contact layer 24 is greater than 1.6 μm.

[0098] The depth of the second cladding layer (31) of the passive waveguide 300 is 100-1000 nm. The second core layer 32 is divided into a first sub-core layer 321 at the lower part and a second sub-core layer 322 at the upper part. The second sub-core layer 322 is in a T-shaped structure, and is connected with the first core layer 22 of the semiconductor optical amplifier (i.e., the optical amplification module 200) through a sub-core layer transmission segment 3221. The width of the sub-core layer transmission segment 3221 is 2-3 μm, and the depth is 0.6 μm.

[0099] The double-layer core layer of the second core layer 32 forms a shallow ridge waveguide structure, which can guide the optical field and reduce the difficulty of manufacturing process and the manufacturing cost.

[0100] ​​In the waveguide detector 400, the width of the absorption layer 42, the third cladding layer 43, and the second P-type contact layer 44 are all 5 to 6 μm, and the depth is approximately 1 to 2 μm.

[0101] The first core layer 22, the first cladding layer 23 of the semiconductor optical amplifier (i.e., optical amplification module 200), the sub-core transmission section 3221 of the passive waveguide 300, and the absorption layer 42, the third cladding layer 43, and the second P-type contact layer 44 of the waveguide detector 400 are formed into an axisymmetric structure, so that the alignment between the passive waveguide and the optical amplifier reaches the optimal level and the coupling efficiency of the optical signal is optimized.

[0102] At the same time, such as Figure 1B As shown, the distance from the edge of the second N-type contact layer 41 of the waveguide detector 400 to the first cladding layer 23 is L1, and the distance from the absorption layer 42 to the first cladding layer 23 is L2; ​​the difference between L2 and L1 is between 0 and 10 μm; in this embodiment, L2-L1 = 6 μm; the difference between the length of the second N-type contact layer 41 extending out, that is, the length of L2 and L1, can reduce the area of ​​the waveguide detector 400 while increasing the bandwidth by 3 dB, without reducing the responsivity of the waveguide detector 400.

[0103] Furthermore, in this embodiment, the height from the upper surface of the second core layer 32 to the bottom of the substrate 100 is H1, and the height from the upper surface of the first core layer 22 to the bottom of the substrate 100 is H2; H2-H1 = 450nm; the height difference, i.e. H2-H1, enables the semiconductor optical amplifier (i.e., optical amplification module 200) and the passive waveguide 300 to achieve optimal alignment, and the optical signal coupling efficiency reaches its maximum.

[0104] Since the waveguide detector 400 and the semiconductor optical amplifier (i.e., the optical amplifier module 200) are connected through an undoped passive waveguide 300, and the P-contacts are not connected to each other (i.e., the first P-type contact layer 24 and the second P-type contact layer 44 are not connected), the waveguide detector 400 and the semiconductor optical amplifier (i.e., the optical amplifier module 200) can be electrically independent.

[0105] The first N-type contact layer 21 is an N-doped InP layer with a thickness of 500 nm; the first core layer 22 includes, from bottom to top: undoped InGaAsP bulk material and InGaAsP multi-quantum well material; wherein the InGaAsP bulk material has a bandgap wavelength of 1.3 μm and a thickness of 125 nm; the InGaAsP multi-quantum well material has a bandgap wavelength of 1.55 μm and a thickness of approximately 250 nm;

[0106] The first cladding layer 23 is a graded-doped P-doped InP layer, consisting of a 500nm lightly doped InP layer and a 1200nm heavily doped InP layer from bottom to top. The concentration of the light doping is 1×10⁻⁶. 17cm -3 , the doping concentration is 1 x 1018cm-3 18 cm -3 ;

[0107] The first P-type contact layer 24 comprises P-doped InGaAsP and In 0.53 Ga 0.47 As layer, wherein the thickness of the InGaAsP is 50 nm, the components of Ga and As are 0.28 and 0.61, and the doping concentration is 3 x 1018cm-3 18 cm -3 ; the thickness of the In 0.53 Ga 0.47 As is 100 nm, and the doping concentration is 1 x 1018cm-3 19 cm -3 ;

[0108] The second cladding layer 31 of the passive waveguide 300 comprises an undoped InP layer with a thickness of 450 nm; the second core layer 32 comprises an undoped InGaAsP layer with a thickness of 1 μm, wherein the components of Ga and As are 0.12 and 0.26;

[0109] In the embodiment, the second N-type contact layer 41 comprises an N-type doped InGaAsP layer and an undoped InP layer; the doping concentration of the InGaAsP layer is 2 x 1018cm-3 18 cm -3 , the thickness is 0.32 μm, and the components of Ga and As are 0.3 and 0.64; the thickness of the InP layer is 10 nm;

[0110] The absorption layer 42 comprises an undoped In 0.53 Ga 0.47 As layer with a thickness of 420 nm; the third cladding layer 43 is a P-type contact layer comprising P-type doped InGaAsP with a thickness of 50 nm, the components of Ga and As are 0.28 and 0.61 respectively, and the doping concentration is 3 x 1018cm-3 18 cm -3 ;

[0111] The second P-type contact layer 44 is a P-type contact layer comprising an In 0.53 Ga 0.47 As layer with a thickness of 100 nm and a doping concentration of 1 x 1018cm-3 19 cm -3 .

[0112] The refractive index of the second N-type contact layer 41 is between the refractive index of the second core layer 32 and the refractive index of the absorption layer 42 in the passive waveguide 300, which provides refractive index matching between the second core layer 32 and the absorption layer 42, and provides a higher optical coupling efficiency for the photodetector;

[0113] In the embodiment, electrodes are arranged on the upper surfaces of the first P-type contact layer 24, the first N-type contact layer 21, the second P-type contact layer 44 and the second N-type contact layer 41 respectively to test the pre-amplified optical detector.

[0114] In the pre-amplified optical detector, the optical signal enters the semiconductor optical amplifier (i.e., the optical amplification module 200) and is directly coupled into the passive waveguide 300, and the optical signal coupled into the passive waveguide 300 is coupled into the absorbing layer 42 by evanescent wave coupling; since the pre-amplified optical detector uses monolithic integration technology, the coupling loss caused by the use of optical fiber interconnection of discrete devices is avoided, and the second N-type contact layer 41 has a longer length in the horizontal plane projection than the absorbing layer 42, thereby improving the evanescent wave coupling efficiency of the waveguide detector 400; the epitaxial layer structure of the semiconductor optical amplifier (i.e., the optical amplification module 200) and the waveguide detector 400 can be freely adjusted to achieve different performances and meet different requirements; the thickness of the second cladding layer 31 in the passive waveguide 300 is optimized to achieve the best level of vertical alignment of the second core layer 32 and the first core layer 22, thereby maximizing the optical coupling efficiency of the optical amplification module 200 and the passive waveguide 300; the semiconductor optical amplifier (i.e., the optical amplification module 200) can provide gain effect for the signal light to improve the sensitivity of the pre-amplified optical detector.

[0115] The present application avoids excessive loss caused by coupling of discrete devices, can improve the received optical power of the optical detector by using the amplification function of the semiconductor optical amplifier (i.e., the optical amplification module 200), improves the optical absorption efficiency of the optical detector by using the evanescent wave coupling effect, and improves the bandwidth of the optical detector by using the semi-insulating substrate 100, while having the performances of miniaturization, low energy consumption, low polarization-dependent loss, high bandwidth, high responsivity and strong scalability.

[0116] Another embodiment of the present application also discloses an optoelectronic detection device, as shown in the accompanying drawings, comprising the pre-amplified optical detector and a waveguide segment 5 as described above; the waveguide segment 5 is arranged on the substrate 100 and comprises: Figure 2

[0117] The first end surface forms a 7° angle with the output end surface of the optical fiber;

[0118] The second end surface is coupled to the optical amplification module (200) of the optical detector; and

[0119] The bending part is located between the first end surface and the second end surface.

[0120] In the embodiment, the optical fiber is coated with an anti-reflection film at the connection end of the waveguide segment 5. ​

[0121] The optical signal enters the optical amplification module 200 through the waveguide segment 5, and the optical amplification module 200 realizes optical signal power enhancement by performing gain on the optical signal;

[0122] The power-enhanced optical signal enters the waveguide detector 400 through the passive waveguide 300, and the waveguide detector 400 converts the optical signal into an electrical signal to realize data transmission.

[0123] In another embodiment of the present application, a preparation method of a pre-amplified optical detector is also disclosed, comprising:

[0124] Step A: sequentially epitaxially growing a first N-type contact layer 21, a first core layer 22, a first cladding layer 23 and a first P-type contact layer 24 on the upper surface of the substrate 100 from bottom to top;

[0125] In the embodiment, the substrate 100 is a semi-insulating InP substrate 100. The layers on the substrate 100, including the first N-type contact layer 21, the first core layer 22, the first cladding layer 23 and the first P-type contact layer 24, are epitaxially grown by a metal organic chemical vapor deposition (MOCVD) method, obtaining a structure as shown in Figure 3 ;

[0126] Step B: forming a silicon dioxide thin layer on the first P-type contact layer 24;

[0127] In the embodiment, a plasma enhanced chemical vapor deposition device (PECVD) is used to grow a silicon dioxide thin layer with a thickness not less than 500 nm;

[0128] Step C: removing a part of the silicon dioxide covering the first P-type contact layer 24 by using a photolithography and dry etching process;

[0129] In the embodiment, a reactive ion etching device (RIE) is used to etch the silicon dioxide thin layer to obtain a vertical silicon dioxide sidewall;

[0130] Step D: etching the structure obtained in Step C by using a dry etching process, to form a structure as shown in Figure 4 ;

[0131] In Step D of the embodiment, an inductively coupled plasma etching device is used for etching, and the etching depth is until the depth of etching the substrate 100 is about 0-200 nm;

[0132] Step E: etching the structure formed in Step D by using a wet etching process to form a certain degree of side etching, to obtain the first N-type contact layer 21, the first core layer 22, the first cladding layer 23 and the first P-type contact layer 24;

[0133] In this embodiment, the epitaxial wafer is etched by using a non-selective etching solution to obtain smooth mesa sidewalls, and the length of the mask extending out is about 800-1000 nm.

[0134] Step F: the structure surface obtained in step E is thoroughly cleaned to remove surface organic contamination, oxide layer and metal ions under the premise of retaining the thin silicon dioxide layer;

[0135] Step G: the substrate 100 obtained in step F is re-epitaxiated from bottom to top by using a MOCVD device to sequentially epitaxiate a second cladding layer 31, a second core layer 32, a first N-type contact layer 21, an absorbing layer 42, a third cladding layer 43 and a second P-type contact layer 44. Since the first P-type contact layer 24 is covered by the thin silicon dioxide layer, the re-epitaxiation will selectively grow on the substrate 100 to form a structure as shown in FIG. 4. Figure 5

[0136] In this embodiment,

[0137] The second cladding layer 31 is an undoped InP layer with a thickness of 450 nm.

[0138] The second core layer 32 is an undoped InGaAsP layer with a thickness of 1 μm, and the components of Ga and As are 0.12 and 0.26 respectively.

[0139] The second N-type contact layer 41 is an N-type contact layer, which includes an N-type doped InGaAsP layer and an undoped InP layer. The doped concentration of the InGaAsP layer is 2×10 18 cm -3 -2, the thickness is 0.32 μm, and the components of Ga and As are 0.3 and 0.64 respectively. The thickness of the InP layer is 10 nm.

[0140] The absorbing layer 42 has a thickness of 420 nm and includes an undoped In 0.53 Ga 0.47 As layer.

[0141] The third cladding layer 43 is a P-type contact layer with a thickness of 50 nm, which includes a P-type doped InGaAsP layer with a doped concentration of 3×10 18 cm -3 -3 and components of Ga and As of 0.28 and 0.61 respectively.

[0142] The second P-type contact layer 44 is a P-type contact layer with a thickness of 100 nm, which includes an In 0.53 Ga 0.47 As layer with a doped concentration of 1×10 19 cm -3 -1.

[0143] ​Step H: etching the structure obtained in step G to form the second N-type contact layer 41, the absorption layer 42, the third cladding layer 43 and the second P-type contact layer 44 of the waveguide detector 400;

[0144] In the embodiment, the length of the second N-type contact layer 41 in horizontal projection is greater than the length of the absorption layer 42 in horizontal projection, as shown in the figure, i.e. L1 Figure 1B

[0145] In the embodiment, 400 nm of SiO2 is grown before etching, and a mask pattern of the device is photoetched and transferred to the SiO2. Then the second P-type contact layer 44 of the waveguide detector 400 is etched by using a dry etching and wet etching method, and the second N-type contact layer 41 is etched by using a wet etching method. The second P-type contact layer is a rectangle with a size of 5 μm x 20 μm, and the etching depth is 950 nm. The second N-type contact layer 41 is a rectangle with a size of 40 μm x 30 μm, and the etching depth is 320 nm. Then the SiO2 on the surface is removed by using an HF acid solution, and 300 nm of SiO2 is grown again.

[0146] Step I: etching the structure obtained in step H to form the passive waveguide 300;

[0147] In the embodiment, the pattern of the optical amplification module 200 and the passive waveguide 300 is first photoetched and transferred to the SiO2 of the structure in step H. Then the passive waveguide 300 is etched by using ICP, and the etching depth is 600 nm, so as to obtain the passive waveguide 300. At this time, the optical amplification module 200 is also etched by about 600 nm, and the remaining first cladding layer 23 is etched by using a selective wet etching method, and the etching depth is 1250 nm.

[0148] Step J: etching the structure obtained in step I to form the optical amplification module 200, so as to obtain the structure as shown in FIG. 1 and FIG. 2. Figure 2

[0149] In the embodiment, 300 nm of SiO2 is first grown, and then the pattern of the first N-type contact layer 21 of the optical amplification module 200 is transferred to the SiO2 by photoetching. Then the first N-type contact layer 21 is etched by using a dry etching method, and the etching depth is 550 nm, so as to form the optical amplification module 200.

[0150] Step K: covering the device with a layer of SiO2 as a passivation film;

[0151] In the embodiment, the thickness of the passivation film is 600 nm.

[0152] ​​It should be noted that, in order to prepare the complete semiconductor optical amplifier and waveguide detector, the passivation film on the first N-type contact layer 21 and the second N-type contact layer needs to be etched to form an N-electrode window, and metal Ti / Au needs to be sputtered in the N-electrode window and an N-electrode lead pattern needs to be etched.

[0153] At this point, the preparation of the pre-amplified optical detector in the embodiment is completed.

[0154] The two embodiments of the present application are described in detail in combination with the drawings. Based on the above description, those skilled in the art should have a clear understanding of the pre-amplified waveguide detector and the preparation method thereof.

[0155] It should be noted that the above definitions of the elements and methods are not limited to the various specific structures, shapes or manners mentioned in the embodiments, and can be simply changed or replaced by those skilled in the art, for example:

[0156] The shape of the first P-type contact layer 24 includes but is not limited to a semicircle or a trapezoid;

[0157] The doping in the epitaxial material of each layer in the pre-amplified waveguide detector can be replaced by uniform doping;

[0158] The doping types of the first N-type contact layer 21 and the second N-type contact layer 41 can be interchanged; the doping types of the first P-type contact layer 24 and the second P-type contact layer 44 can be interchanged;

[0159] The present application can also be applied to other types of substrates or other materials to prepare pre-amplified optical detectors, as long as the relevant structures are met, and should also be included in the protection scope of the present application.

[0160] In addition, the implementation modes not shown or described in the drawings or the specification are known to those skilled in the art, and are not described in detail. The directional terms mentioned in the embodiments, such as "up", "down", "left", "right", etc., are only with reference to the direction of the drawings, and are not intended to limit the protection scope of the present application. This document can improve the demonstration of specific values, but these parameters do not need to be exactly equal to the corresponding values, but can be approximately equal to the corresponding values within an acceptable error tolerance or design constraint. And in the preparation method, unless the steps described or must occur in sequence are limited to the above, and can be changed or rearranged according to the required design.

[0161] In summary, the application constructs the main structure of the pre-amplification optical detector by semiconductor process, realizes the compatibility of the semiconductor optical amplifier (i.e. optical amplification module 200) and the waveguide detector 400 by the secondary epitaxy technology. The end-to-end connection of the semiconductor optical amplifier (i.e. optical amplification module 200) and the passive waveguide 300 realizes the high-efficiency coupling of the optical signal and the independent design of each part of the device. The longer length of the second N-type contact layer relative to the absorption layer 42 in the horizontal plane projection in the waveguide detector 400 improves the 3dB bandwidth of the pre-amplification optical detector under the premise of ensuring the responsivity of the pre-amplification optical detector. The semiconductor optical amplifier (i.e. optical amplification module 200) amplifies the optical signal, greatly improves the sensitivity of the pre-amplification optical detector. The pre-amplification optical detector has the advantages of low coupling loss, strong scalability, high speed and high responsivity, and has a broad application prospect.

[0162] The above specific embodiments further illustrate the purpose, technical scheme and beneficial effects of the application, and it should be understood that the above description is only for specific embodiments of the application and is not intended to limit the application. Any modification, equivalent replacement, improvement, etc. within the spirit and principle of the application shall be included in the protection scope of the application.

Claims

1. A pre-amplified photodetector, characterized in that, include: The substrate (100) includes a magnification region, a passive region and a detection region that are sequentially adjacent to each other; An optical amplification module (200) is disposed in an amplification region on the substrate (100) for enhancing the power of the optical signal and includes a first core layer (22). A passive waveguide (300) has a passive region and a detection region disposed on the substrate (100), and includes a second core layer (32); a power-enhanced optical signal is coupled from the first core layer (22) to the second core layer (32) of the passive waveguide (300); and A waveguide detector (400) is disposed on a passive waveguide (300) in the detection area; the optical signal enters the waveguide detector (400) from the second core layer (32) in an evanescent wave coupling manner, and is converted into an electrical signal by the waveguide detector (400); The side of the first core layer (22) is connected to the side of the second core layer (32) to improve the coupling efficiency of the optical signal.

2. The photodetector according to claim 1, characterized in that, The optical amplification module (200) also includes: A first N-type contact layer (21) is disposed on the substrate (100) and is connected to the first surface of the first core layer (22); A first cladding layer (23) is disposed on a second surface of the first core layer (22), the first surface being opposite to the second surface; and A first P-type contact layer (24) is disposed on the first cladding layer (23); The passive waveguide (300) also includes: The second cladding layer (31) is disposed on the substrate (100) and is connected to the first surface of the second core layer (32); the thickness of the second cladding layer (31) is 200 nm to 1000 nm.

3. The photodetector according to claim 1, characterized in that, The second core layer (32) includes: a first sub-core layer (321) and a second sub-core layer (322) disposed on the first sub-core layer (321); The second sub-core layer (322) includes a sub-core layer transmission segment (3221) connected to the first core layer (22); The sub-core transmission segment (3221) and the first core layer (22) form an axisymmetric structure in the incident direction of light to improve the coupling efficiency of the optical signal coupled from the first core layer (22) to the second core layer (32).

4. The photodetector according to claim 1, characterized in that, The distance from the second surface of the first core layer (22) to the bottom of the substrate (100) is H1. The distance from the second surface of the second core layer (32) to the bottom of the substrate (100) is H2; where H1 < H2.

5. The photodetector according to claim 4, characterized in that, The difference between H2 and H1 is 250 to 650 nm.

6. The photodetector according to claim 1, characterized in that, The waveguide detector (400) includes: A second N-type contact layer (41) is disposed on the passive waveguide (300); An absorption layer (42) is disposed on the second N-type contact layer (41); A third cladding layer (43) is disposed on the absorbent layer (42); A second P-type contact layer (44) is disposed on the third cladding layer (43); The distance from the second N-type contact layer (41) to the optical amplification module (200) is L1, and the distances from the absorption layer (42), the third cladding layer (43), and the second P-type contact layer (44) to the optical amplification module (200) are all L2, with L1 < L2, in order to improve the evanescent wave coupling efficiency of the optical signal.

7. The photodetector according to claim 6, characterized in that, The difference between L2 and L1 ranges from 1 to 10 μm.

8. The photodetector according to claim 6, characterized in that, The optical refractive index of the second N-type contact layer (41) is between that of the second core layer (32) and the optical refractive index of the absorption layer (42), so that the optical signal enters the absorption layer (42) through the second N-type contact layer (41) in an evanescent wave coupling manner.

9. The photodetector according to claim 6, characterized in that, The second N-type contact layer (41) uses InGaAsP and InP as its materials; The absorber layer (42) is made of InGaAs; The material used for the third cladding layer (43) includes P-type doped InGaAsP; The material used in the second P-type contact layer (44) includes InGaAs.

10. The photodetector according to claim 1, characterized in that, The substrate (100) is made of InP; The first core layer (22) uses materials including undoped InGaAsP bulk material and InGaAsP multi-quantum-well material; The second core layer (32) is made of undoped InGaAsP material.

11. A method for fabricating a pre-amplified photodetector as described in any one of claims 1 to 10, characterized in that, include: S1: An optical amplification module (200) is fabricated on a substrate (100), the optical amplification module (200) being located in the amplification region on the substrate (100); S2: A passive waveguide (300) is fabricated on the substrate (100) on one side of the optical amplification module (200) obtained in step S1. The passive waveguide (300) is located in the passive region and the detection region on the substrate (100). S3: A waveguide detector (400) is fabricated on the passive waveguide (300) located in the detection area to obtain the pre-amplified photodetector.

12. A photoelectric detection device, characterized in that, include: A pre-amplified photodetector as described in any one of claims 1 to 10; as well as Waveguide segment (5), disposed on the substrate (100), includes: The first end face forms a 7° angle with the fiber output end face; The second end face is coupled to the optical amplification module (200) of the photodetector; and The bent portion is located between the first end face and the second end face.

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