CN116706678A

CN116706678A - Semiconductor optical amplifier and preparation method thereof

Info

Publication number: CN116706678A
Application number: CN202310527444.XA
Authority: CN
Inventors: 单静春; 李中坤; 李吴皓; 王定理; 赵建宜; 黄晓东
Original assignee: Accelink Technologies Co Ltd
Current assignee: Accelink Technologies Co Ltd
Priority date: 2023-05-08
Filing date: 2023-05-08
Publication date: 2023-09-05

Abstract

The embodiment of the disclosure provides a semiconductor optical amplifier and a preparation method thereof, wherein the semiconductor optical amplifier comprises a waveguide structure, the waveguide structure is U-shaped, and the semiconductor optical amplifier comprises: the two ends of the U-shaped waveguide structure are respectively used as an input end and an output end of the semiconductor optical amplifier, the input end and the output end are both positioned on the optical coating surface of the semiconductor optical amplifier, and the waveguide structure is inclined relative to the optical coating surface. In this way, the input end and the output end are arranged on the same end face (optical film plating face) of the semiconductor optical amplifier by utilizing the U-shaped waveguide structure, so that the optical film is plated once in the process, the process steps are reduced, and the process flow is optimized. In addition, by adopting an inclined waveguide structure, the resonance of light waves in the semiconductor optical amplifier is effectively avoided, and the spectrum ripple wave is reduced.

Description

Semiconductor optical amplifier and preparation method thereof

Technical Field

The disclosure relates to the technical field of semiconductors, and in particular relates to a semiconductor optical amplifier and a preparation method thereof.

Background

A semiconductor optical amplifier (Semiconductor Optical Amplifier, SOA) is an optoelectronic device that uses semiconductor material as a gain medium to amplify or provide gain to external photons. The SOA has the advantages of small volume, high nonlinearity, low power consumption, convenience in integration and the like, and can be used as a gain device such as a power amplifier, a relay amplifier, a preamplifier and the like, and also can be used as a key part of a functional device such as an optical switch and a wavelength converter. Typically, an SOA is used to amplify external photons, which has two ports, an input and an output. At present, an input end and an output end of an SOA are respectively arranged on the front end face and the rear end face of a chip, so that optical films are required to be respectively coated on the front end face and the rear end face, and the process steps are complicated.

Disclosure of Invention

The embodiment of the disclosure provides a semiconductor optical amplifier and a preparation method thereof.

In a first aspect, embodiments of the present disclosure provide a semiconductor optical amplifier comprising a waveguide structure, the waveguide structure being U-shaped, wherein:

the two ends of the U-shaped waveguide structure are respectively used as an input end and an output end of the semiconductor optical amplifier, the input end and the output end are both positioned on an optical coating surface of the semiconductor optical amplifier, and the waveguide structure is inclined relative to the optical coating surface.

In some embodiments, the waveguide structure includes an input portion, a turn portion, and an output portion, the input portion and the output portion being linear, the turn portion being curved, the turn portion being connected to the input portion and the output portion, respectively, the input portion and the output portion being parallel; wherein: the included angle between the input part and the normal line of the optical coating surface is 0-18 degrees.

In some embodiments, the distance of the input end to a tangent of the apex of the turning portion is: 500-3000 μm, the distance from the output end to the tangent line of the vertex of the turning part is: 500-3000 μm, the distance between the input portion and the output portion being: 250-2000 mu m;

wherein the vertex of the turning part is the tangent point of a straight line perpendicular to both the input part and the output part at the turning part.

In some embodiments, the semiconductor optical amplifier includes a lower electrode layer, a substrate layer, a buffer layer, an active layer, a corrosion resistant layer, an upper cladding layer, an ohmic contact layer, an insulating layer, and an upper electrode layer, which are sequentially stacked; wherein the active layer is located at least below the waveguide structure.

In some embodiments, a first U-shaped trench and a second U-shaped trench are formed within the ohmic contact layer and the upper cladding layer, and the second U-shaped trench is located at an outer periphery of the first U-shaped trench, the waveguide structure including the upper cladding layer and the ohmic contact layer between the first U-shaped trench and the second U-shaped trench; wherein:

the insulating layer is formed on the side wall and the bottom of the first U-shaped groove, the side wall and the bottom of the second U-shaped groove and the surface of the ohmic contact layer except the waveguide structure;

the upper electrode layer is formed in the first U-shaped groove, in the second U-shaped groove, above the waveguide structure and on a portion of the top surface of the insulating layer.

In some embodiments, the optical coating surface is a front end surface of the semiconductor optical amplifier, and the optical coating surface is coated with at least one anti-reflection film.

In a second aspect, an embodiment of the present disclosure provides a method for manufacturing a semiconductor optical amplifier, including:

providing an epitaxial wafer, wherein the top layer of the epitaxial wafer is a waveguide layer;

forming a waveguide structure in the waveguide layer, wherein the waveguide structure is U-shaped, and the waveguide structure comprises:

In some embodiments, the providing an epitaxial wafer includes:

sequentially forming a stacked substrate layer, a buffer layer, an active layer, an anti-corrosion layer, an upper cladding layer and an ohmic contact layer; wherein the ohmic contact layer and the upper cladding layer constitute the waveguide layer.

In some embodiments, forming a waveguide structure within the waveguide layer includes:

forming a first U-shaped groove and a second U-shaped groove in the ohmic contact layer and the upper cladding layer, wherein the second U-shaped groove is positioned at the periphery of the first U-shaped groove, and the waveguide structure comprises the upper cladding layer and the ohmic contact layer which are positioned between the first U-shaped groove and the second U-shaped groove;

the first U-shaped groove and the second U-shaped groove are inclined relative to the optical coating surface.

In some embodiments, the method further comprises:

forming an insulating layer on the side walls and the bottoms of the first U-shaped groove and the second U-shaped groove and above the ohmic contact layer except the waveguide structure;

forming an upper electrode layer in the first U-shaped groove and the second U-shaped groove, above the waveguide structure and above a part of the top surface of the insulating layer;

and thinning the bottom surface of the epitaxial wafer, and forming a lower electrode layer on the bottom surface of the epitaxial wafer.

In some embodiments, the optical plating surface is a front end surface of the semiconductor optical amplifier, the method further comprising:

and forming at least one layer of anti-reflection film on the optical coating film.

The embodiment of the disclosure provides a semiconductor optical amplifier and a preparation method thereof, wherein the semiconductor optical amplifier comprises a waveguide structure, the waveguide structure is U-shaped, and the semiconductor optical amplifier comprises: the two ends of the U-shaped waveguide structure are respectively used as an input end and an output end of the semiconductor optical amplifier, the input end and the output end are both positioned on the optical coating surface of the semiconductor optical amplifier, and the waveguide structure is inclined relative to the optical coating surface. In this way, the input end and the output end are arranged on the same end face (optical film plating face) of the semiconductor optical amplifier by utilizing the U-shaped waveguide structure, so that the optical film is plated once in the process, the process steps are reduced, and the process flow is optimized. In addition, the waveguide structure is inclined relative to the optical coating surface, and the inclined waveguide structure is adopted, so that light waves can be effectively prevented from resonating in the semiconductor optical amplifier, and spectral ripples are further reduced.

Drawings

Fig. 1 is a schematic structural diagram of a semiconductor optical amplifier according to an embodiment of the disclosure;

fig. 2 is a schematic perspective view of a semiconductor optical amplifier according to an embodiment of the disclosure;

FIG. 3 is a schematic diagram of a waveguide structure provided by an embodiment of the present disclosure;

fig. 4 is a schematic top view of a semiconductor optical amplifier according to an embodiment of the disclosure;

fig. 5 is a schematic front view of a semiconductor optical amplifier according to an embodiment of the disclosure;

fig. 6 is a schematic flow chart of a method for manufacturing a semiconductor optical amplifier according to an embodiment of the disclosure;

fig. 7 is a schematic diagram of an epitaxial wafer according to an embodiment of the disclosure;

FIG. 8 is a schematic diagram of a resulting structure after forming a waveguide structure according to an embodiment of the present disclosure;

FIG. 9 is a schematic top view of a resulting structure after forming a waveguide structure according to an embodiment of the present disclosure;

FIG. 10 is a schematic diagram of a structure obtained after forming an insulating layer according to an embodiment of the present disclosure;

FIG. 11 is a schematic diagram of a structure obtained after forming an upper electrode layer according to an embodiment of the present disclosure;

FIG. 12A is a schematic diagram of a structure after forming a first initial insulating layer according to an embodiment of the present disclosure;

FIG. 12B is a schematic illustration of a structure after forming a second initial insulating layer according to an embodiment of the present disclosure;

fig. 13 is a schematic structural diagram of a circuit system according to an embodiment of the disclosure.

Detailed Description

The technical solutions in the embodiments of the present disclosure will be clearly and completely described below with reference to the drawings in the embodiments of the present disclosure. It is to be understood that the specific embodiments described herein are merely illustrative of the related disclosure and not limiting thereof. It should be further noted that, for convenience of description, only the portions related to the disclosure are shown in the drawings.

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 disclosure belongs. The terminology used herein is for the purpose of describing embodiments of the present disclosure only and is not intended to be limiting of the present disclosure.

In the following description, reference is made to "some embodiments" which describe a subset of all possible embodiments, but it is to be understood that "some embodiments" can be the same subset or different subsets of all possible embodiments and can be combined with one another without conflict.

It should be noted that the term "first\second\third" in relation to the embodiments of the present disclosure is merely to distinguish similar objects and does not represent a particular ordering for the objects, it being understood that the "first\second\third" may be interchanged in a particular order or sequencing where allowed, so that the embodiments of the present disclosure described herein may be implemented in an order other than that illustrated or described herein.

The SOA is an optoelectronic device which takes a semiconductor material as a gain medium and can amplify or provide gain to external photons, and has the advantages of small volume, high nonlinearity, low power consumption, convenience in integration and the like. The SOA has two ports, an input and an output. In the prior art, an input end and an output end are usually respectively arranged on the front end face and the rear end face of a chip, so that optical films are required to be respectively coated on the front end face and the rear end face of the chip, and the process steps are complicated.

Based on this, the disclosed embodiments provide a semiconductor optical amplifier including a waveguide structure, the waveguide structure being U-shaped, wherein: the two ends of the U-shaped waveguide structure are respectively used as an input end and an output end of the semiconductor optical amplifier, the input end and the output end are both positioned on the optical coating surface of the semiconductor optical amplifier, and the waveguide structure is inclined relative to the optical coating surface. In this way, the waveguide structure in the semiconductor optical amplifier is designed into a U shape, so that the input end and the output end of the semiconductor optical amplifier are positioned on the same end face (optical film plating face) of the semiconductor optical amplifier, and therefore, only one optical film needs to be plated in the process of manufacturing a chip, the process steps are effectively reduced, the process flow is optimized, and the manpower and material resources are saved; in addition, the waveguide structure is inclined relative to the optical coating surface, so that resonance of light waves in the semiconductor optical amplifier can be effectively avoided, and the reduction of spectrum ripple waves is facilitated; further, the semiconductor optical amplifier with the structure has smaller volume, and is beneficial to integrated packaging with other devices.

Embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings.

In one embodiment of the present disclosure, referring to fig. 1, a schematic diagram of a semiconductor optical amplifier 10 provided in an embodiment of the present disclosure is shown. As shown in fig. 1, the semiconductor optical amplifier 10 includes a waveguide structure 20, the waveguide structure 20 having a U-shape, wherein:

the two ends of the U-shape of the waveguide structure 20 are respectively an input end and an output end of the semiconductor optical amplifier 10, the input end and the output end are both positioned on the optical coating surface of the semiconductor optical amplifier 10, and the waveguide structure 20 is inclined relative to the optical coating surface.

It should be noted that, the solution provided by the embodiments of the present disclosure is applicable to various material systems, such as a material system of gallium arsenide indium/indium phosphide (InGaAsP/InP) system material, aluminum gallium indium arsenide/indium phosphide (AlGaInAs/InP) system material, aluminum gallium arsenide/gallium arsenide (AlGaAs/GaAs) system material, and so on; meanwhile, the method is applicable to various planar active layer buried heterostructures, such as structures of corrosion mesa buried structures, double-ditch planar buried structures, stripe buried heterostructures and the like; and is applicable to various non-planar active layer buried heterostructures, such as V-groove substrate or channel substrate buried structures, mesa substrate buried heterostructures, buried crescent structures, etc., without any limitation herein. In addition, the scheme of the embodiment of the disclosure is also applicable to SOAs with various wavelengths, for example: 850nm, 980nm, 1060nm, 1310nm, 1550nm, etc., and is not limited in any way herein.

It should be further noted that fig. 1 is a schematic top view of a semiconductor optical amplifier 10 according to an embodiment of the disclosure, where the semiconductor optical amplifier is also referred to as an SOA, an SOA chip, or the like. As shown in fig. 1, a waveguide structure 20 is formed in the semiconductor optical amplifier 10, the waveguide structure 20 has a U shape, and both ends of the "U" are respectively an input end (or light-in end) and an output end (or light-out end) of the waveguide structure 20. In the drawings of the embodiments of the present disclosure, the port (1) is taken as an input end and the port (2) is taken as an output end as examples, but the port (2) may be taken as an input end and the port (1) may be taken as an output end, which is not particularly limited.

As shown in fig. 1, the U-shaped waveguide structure 20 is also inclined at an angle with respect to the optically coated surface of the semiconductor optical amplifier 10.

In this way, the embodiment of the disclosure adopts the U-shaped inclined curved waveguide structure, and the input end and the output end of the SOA chip are arranged on the same side, so that in the process of manufacturing the chip, only one optical film needs to be plated (the optical film plating surfaces where the input end and the output end are located are plated), while in the conventional manner, the input end and the output end are respectively located at two end surfaces of the SOA chip, and the optical film needs to be respectively plated at the end surface where the input end is located and the end surface where the output end is located. In contrast, in the embodiment of the disclosure, the input end and the output end are arranged on the same side, so that the process steps are reduced, the process flow is optimized, and the manpower and material resources are saved. In addition, by adopting an inclined waveguide structure, the resonance of light waves in the semiconductor optical amplifier is effectively avoided, and the spectrum ripple wave is reduced. In addition, the SOA chip provided by the embodiment of the disclosure is smaller in size, so that the SOA chip is more convenient to integrate and package with other devices.

Further, referring to fig. 2, a schematic perspective view of a semiconductor optical amplifier 10 according to an embodiment of the present disclosure is shown. As shown in fig. 2, in the semiconductor optical amplifier 10, at least an active layer 13 and a waveguide structure 20 are included, wherein the active layer 13 corresponds to the waveguide structure 20 vertically, and an active region is ensured to exist right below the waveguide structure 20, so that normal operation of the device is ensured. That is, the active layer 13 is located at least below the waveguide structure 20.

For a more detailed description of the waveguide structure 20, reference is made to fig. 3, which shows a schematic diagram of one waveguide structure 20 provided by an embodiment of the present disclosure. As shown in fig. 3, in some embodiments, the waveguide structure 20 includes an input portion 201, a turn portion 202, and an output portion 203, where the input portion 201 and the output portion 203 are linear, the turn portion 202 is curved, and the turn portion 202 is connected to the input portion 201 and the output portion 203, respectively, and the input portion 201 and the output portion 203 are parallel.

It should be noted that, as shown in fig. 3, the waveguide structure 20 may be divided into three parts (it is understood that the three parts are actually integrated, and such division is only for convenience of description). Specifically, a straight portion including an input end is referred to as an input portion 201, a straight portion including an output end is referred to as an output portion 203, and a curved portion located between the input portion 201 and the output portion 203 is referred to as a turning portion 202. It will be appreciated that fig. 3 is merely exemplary, and 201 in fig. 3 represents an output portion if port (1) is an output, and 203 in fig. 3 represents an input portion if port (2) is an input.

Fig. 4 is a schematic plan view corresponding to fig. 2, fig. 5 is a schematic front view corresponding to fig. 2, and fig. 5 shows more detailed information than fig. 2.

In some embodiments, as shown in fig. 4, port (1) corresponds to the light-in position, representing the input end, and port (2) corresponds to the light-out position, representing the output end. Wherein the included angle between the input part 201 and the normal line of the optical coating surface is 0-18 degrees.

Since the input portion 201 and the output portion 203 are parallel, the inclination angle of the input portion 201 with respect to the optical plating surface and the inclination angle of the output portion 203 with respect to the optical plating surface are the same. In the embodiment of the present disclosure, the inclination degree of the U-shaped waveguide structure 20 relative to the optical coating surface is represented by the angle between the straight line portion (including the input portion 201 and the output portion 203) of the U-shaped waveguide structure 20 and the normal line of the optical coating surface.

As shown in fig. 4 (refer to fig. 3 in combination), the angle between the input portion 201 and the normal line of the optical plating surface is denoted by θ, and the specific value of θ may be set in combination with the actual application scenario and the characteristics of the material, and may be determined by experiments or the like, which is not particularly limited.

Illustratively, θ ranges from 0 ° to 18 °, preferably, the angle range of θ includes 18 ° and does not include 0 ° (when θ is 0 °, the straight portion of the U-shaped waveguide structure 20 is perpendicular to the optical coating surface), but is not absolutely limited.

In this way, the embodiment of the disclosure adopts the inclined U-shaped waveguide structure, so that the emergent light and the incident light waveguide are not in the same straight line, and the emitted light cannot be completely transmitted back along the light waveguide at the end face, thereby inhibiting the reflected light generated by the end face, reducing the total residual reflectivity of the end face of the chip, further reducing the ripple wave of the chip and optimizing the optical performance of the chip. In addition, the structure of the full inclined cavity (namely, the U-shaped waveguide is inclined relative to the optical coating surface) is adopted, compared with other structures, the optical path bending is less in the optical transmission process, the loss of light transmitted along the waveguide is small, and the optical gain is larger.

It should be noted that, as shown in fig. 3, the U-shaped waveguide structure 20 has an approximately symmetrical structure along the symmetry axis shown by the dotted line. It will be appreciated that the approximation here is due to: since the U-shaped waveguide structure is disposed obliquely with respect to the optical coating surface of the semiconductor optical amplifier 10, the length of the input portion 201 and the length of the output portion 203 are not exactly the same, but have a certain deviation, and the magnitude of the deviation is related to the magnitude of θ.

In some embodiments, as shown in FIG. 4, the distance L1 of the input end to the tangent of the apex of the turn portion 202 is: 500-3000 μm, the distance L2 of the tangent line of the output end to the apex of the turning section 202 is: 500-3000 μm, the distance w between the input portion 201 and the output portion 203 is: 250-2000 mu m.

Wherein the apex of the turning section 202 is the tangent point of a straight line perpendicular to both the input section 201 and the output section 203 at the turning section 202.

It should be noted that, as shown in fig. 4, this embodiment may determine a straight line perpendicular to both the input portion 201 and the output portion 203 and tangential to the turning portion 202, and the tangent point of the straight line at the turning portion 202 is the vertex of the turning portion 202. In fig. 4, the turning portion 202 has a regular symmetrical shape, and in practice, the turning portion 202 may be asymmetrical.

The distance from the input end (port (1) in fig. 4) to the straight line is denoted as L1, the distance from the output end (port (2) in fig. 4) to the straight line is denoted as L2, and L1 and L2 represent the lengths of the waveguide structures 20 on one side, respectively. In which L1 and L2 may each range from 500 to 3000 μm, it is understood that since the waveguide structure 20 is an inclined waveguide structure, there is a certain difference between the values of L1 and L2.

As shown in fig. 4, the range of the distance W between the input portion 201 and the output portion 203 is: 250-2000 mu m. In addition, in this example, the waveguide structure 20 is a ridge waveguide structure, and the distance between straight portions of the U-shaped waveguide can also be characterized by a distance W1 between grooves (first U-shaped grooves 21 described later) inside the ridge waveguide, and the range of W1 may be, for example: 250-2000 mu m.

In some embodiments, as shown in fig. 5, the semiconductor optical amplifier 10 includes a lower electrode layer 19, a substrate layer 11, a buffer layer 12, an active layer 13, an anti-corrosion layer 14, an upper cladding layer 15, an ohmic contact layer 16, an insulating layer 17, and an upper electrode layer 18, which are stacked in this order.

The substrate layer 11 may be an n-type InP substrate, the buffer layer 12 may be an n-type InP buffer layer or an InGaAsP buffer layer, the active layer 13 may be an InGaAsP active layer, the corrosion-resistant layer 14 may be a P-type InGaAsP corrosion-resistant layer, the upper cladding layer 15 may be a P-type InP upper cladding layer or an InGaAsP upper cladding layer, the ohmic contact layer 16 may be a highly doped P-type InGaAs ohmic contact layer, and the insulating layer 17 may be an SiO2 insulating layer; the electrode materials of the upper electrode layer 18 and the lower electrode layer 19 may be a metal material such as titanium (Ti), platinum (Pt), or gold (Au), or a conductive material.

Here, the upper electrode layer 18 is in contact with the P-type ohmic contact layer 16, and thus, the surface of the ohmic contact layer 16 may be referred to as a P-face of the semiconductor optical amplifier 10, and the upper electrode layer 18 may also be referred to as a P-face electrode or a P-face metal electrode; in the same manner, since the lower electrode layer 19 is in contact with the n-type substrate layer 11, the surface of the substrate layer 11 may be referred to as the n-side of the semiconductor optical amplifier 10, and the lower electrode layer 19 may be referred to as an n-side electrode or an n-side metal electrode.

In some embodiments, a first U-shaped trench 21 and a second U-shaped trench 22 are formed within the ohmic contact layer 16 and the upper cladding layer 17, and the second U-shaped trench 22 is located at the outer periphery of the first U-shaped trench 21, and the waveguide structure 20 includes the upper cladding layer 15 and the ohmic contact layer 16 between the first U-shaped trench 21 and the second U-shaped trench 22; wherein:

the insulating layer 17 is formed on the side walls and bottom of the first U-shaped trench 21, the side walls and bottom of the second U-shaped trench 22, and the surface of the ohmic contact layer 16 except for the waveguide structure 20;

the upper electrode layer 18 is formed in the first U-shaped trench 21, in the second U-shaped trench 22, above the waveguide structure 20 and a part of the top surface of the insulating layer 17.

In fig. 4 and 5, the positions of the first U-shaped trench 21 and the second U-shaped trench 21 are indicated by arrows, and it is understood that in the semiconductor optical amplifier 10, the insulating layer 17 and the upper electrode layer 18 are formed in the first U-shaped trench 21 and the second U-shaped trench 22.

In addition, in the embodiment of the present disclosure, as shown in fig. 4 and 5, the waveguide structure 20 is a ridge waveguide, but in other examples, the waveguide structure 20 may be a planar waveguide, a columnar waveguide, a buried waveguide, or the like, which is not limited herein, and only a ridge waveguide is taken as an example.

In some embodiments, the optically coated surface is the front end surface of the semiconductor optical amplifier 10, which is coated with at least one anti-reflective film.

The front end surface is a front view plane shown in fig. 5, and the surface facing the front end surface is a rear end surface. In the related art, the front end face and the rear end face are both coated surfaces, so that the process is complex and the cost is high. Wherein, at least one layer of anti-reflection film (or anti-reflection dielectric film) is plated on the optical coating surface, thereby being capable of increasing the light transmittance, reducing the reflectivity, being beneficial to improving the performance of the SOA and guaranteeing the working reliability of the SOA.

Briefly, an embodiment of the disclosure relates to a structural design of a semiconductor optical amplifier, and belongs to the technical field of semiconductor light emitting devices. As shown in fig. 4, the U-shaped inclined curved waveguide structure 20 has a certain angle θ with the normal line of the exit end face (also the incident end face, i.e., the optical film coated face described above), the width between the two side waveguides is W, and the length of the one side waveguide is L (L1 and L2). As can be seen from fig. 4, the light-in end face and the light-out end face of the SOA chip are on the same end face. The structure can ensure subsequent packaging and indexes, and the curvature radius of the U-shaped inclined waveguide structure is as small as possible, so that the size of the SOA is reduced. In addition, the waveguide structure is a full-inclined cavity waveguide, and no waveguide bending exists in the middle, so that the waveguide transmission loss is small, and the chip gain is large.

That is, the core of the present solution is at least: and a U-shaped turning inclined bent waveguide structure is manufactured on the SOA chip, and the light emitting surface and the light entering surface of the SOA chip are arranged on the same end face, so that the process steps are optimized. Furthermore, the present disclosure includes, but is not limited to, U-turn angled bent waveguides, any dual waveguide structure of any shape, whether angled or not, based on the present disclosure, as long as the above objectives are achieved, and whatever the specific structure differs, is within the scope of the present disclosure.

In another embodiment of the present disclosure, referring to fig. 6, a schematic flow chart of a method for manufacturing a semiconductor optical amplifier according to an embodiment of the present disclosure is shown. As shown in fig. 6, the method may include:

s601: and providing an epitaxial wafer, wherein the top layer of the epitaxial wafer is a waveguide layer.

The providing of the epitaxial wafer may include:

sequentially forming a stacked substrate layer 11, a buffer layer 12, an active layer 13, an anti-corrosion layer 14, an upper cladding layer 15, and an ohmic contact layer 16; wherein the ohmic contact layer 16 and the upper cladding layer 15 constitute a waveguide layer.

It should be noted that the embodiments of the present disclosure may form a multi-layer material by an epitaxial manner, so as to obtain an epitaxial wafer, and further process the epitaxial wafer, so as to form the waveguide structure 20 therein, and further obtain the semiconductor optical amplifier 10.

Referring to fig. 7, a schematic structural diagram of an epitaxial wafer according to an embodiment of the disclosure is shown, which is a schematic front view. As shown in fig. 7, a substrate layer 11 is first provided, and then a stacked buffer layer 12, active layer 13, anti-corrosion layer 14, upper cladding layer 15, and ohmic contact layer 16 are sequentially formed on the substrate layer 11 by epitaxial means.

The substrate layer 11 may be an n-type InP substrate, the buffer layer 12 may be an n-type InP buffer layer or an InGaAsP buffer layer, the active layer 13 may be an InGaAsP active layer, the anti-corrosion layer 14 may be a P-type InGaAsP anti-corrosion layer, the upper cladding layer 15 may be a P-type InP upper cladding layer or an InGaAsP upper cladding layer, and the ohmic contact layer 16 may be a highly doped P-type InGaAs ohmic contact layer. Alternatively, the layers may be other types of materials known to those skilled in the art, which are not particularly limited.

In the embodiment of the present disclosure, the active layer 13 may be a buried heterojunction (Bury Heterogeneous, BH) structure or a bulk material (ridge waveguide structure) or the like, but is not limited thereto. Here, a specific manufacturing method of the SOA chip is described by taking the SOA chip with the active layer as a bulk material.

Wherein each layer (which may be referred to as an epitaxial layer) in the respective epitaxial wafer may be obtained by one or more metal organic chemical vapor deposition (Metal Organic Chemical Vapor Deposition, MOCVD).

S602: and forming a waveguide structure in the waveguide layer, wherein the waveguide structure is U-shaped.

The forming of the waveguide structure in the waveguide layer may include:

a first U-shaped trench 21 and a second U-shaped trench 22 are formed in the ohmic contact layer 16 and the upper cladding layer 15, and the second U-shaped trench 22 is located at the outer periphery of the first U-shaped trench 21, and the waveguide structure 20 includes the upper cladding layer 15 and the ohmic contact layer 16 formed between the first U-shaped trench 21 and the second U-shaped trench 22.

Fig. 8 is a schematic diagram of a structure obtained after forming the waveguide structure 20 according to the embodiment of the disclosure on the basis of fig. 7, and fig. 9 is a schematic top view corresponding to fig. 8. As shown in connection with fig. 8 and 9, for the first U-shaped groove 21 and the second U-shaped groove 22, the "U" shape refers to the shape of the letter "U" as seen from the top view. Wherein, the first U-shaped groove 21 is located at the inner periphery of the second U-shaped groove 22, and the waveguide layer reserved between the first U-shaped groove 21 and the second U-shaped groove 22 is the waveguide structure 20, and it can be seen that the waveguide structure 20 in a U shape is obtained based on the restriction shaping of the two U-shaped grooves.

As shown in fig. 9, the first U-shaped groove 21 and the second U-shaped groove 22 are inclined with respect to the optical plating surface.

It should be noted that the first U-shaped groove 21 and the second U-shaped groove 22 have the same shape and characteristics, but the first U-shaped groove 21 is located at the inner periphery of the second U-shaped groove 22, and both are inclined at a certain angle with respect to the optical coating surface, so that the waveguide structure 20 defined by both is also inclined at a certain angle with respect to the optical coating surface.

Here, the angle at which the U-shaped groove is inclined with respect to the optical coating surface (and also the angle at which the U-shaped waveguide structure 20 is inclined with respect to the optical coating surface) is characterized by the angle between the straight portion of the "U" and the normal line of the optical coating surface. The included angle is denoted as θ and may range from 0 to 18 °.

Thus, the inclined U-shaped waveguide structure is prepared by the embodiment of the disclosure, so that the outgoing light and the incident light waveguide are not in the same straight line, and the emitted light cannot be completely transmitted back along the light waveguide at the end face, thereby inhibiting the reflected light generated by the end face, reducing the total residual reflectivity of the end face of the chip, further reducing the ripple wave of the chip and optimizing the optical performance of the chip. In addition, the structure of the full inclined cavity is adopted, compared with other structures, the light path bending is less in the light transmission process, the loss of light transmission along the waveguide is small, and the light gain is larger. In addition, the SOA chip manufactured by the method is smaller in size and convenient to integrate.

As shown in fig. 8, the waveguide structure 20 is a ridge waveguide structure, but the type of the waveguide structure 20 is not particularly limited and only a ridge waveguide is described as an example.

In forming the first and second U-shaped trenches 21 and 22, a trench mask layer may be formed over the ohmic contact layer 16, the trench mask layer exposing regions of the first and second U-shaped trenches 21 and 22 and covering other regions, it being understood that the trench mask layer has two "U" -shaped patterns, and one U-shaped pattern is located at the outer circumference of the other U-shaped pattern. The ohmic contact layer 16 and the upper cladding layer 15 under the region exposed by the trench mask layer are then removed, thereby obtaining a first U-shaped trench 21 and a second U-shaped trench 22, and finally the trench mask layer is also removed. The trench mask layer may be formed by deposition, and the material of the trench mask layer may be silicon oxide, silicon nitride, photoresist, or the like.

In embodiments of the present disclosure, the U-shaped inclined mesa waveguide structure may be fabricated on a plane by photolithography and etching (e.g., dry etching, chemical etching, a combination of dry etching and chemical etching), and the like. Illustratively, when dry etching is used, a Reactive Ion Etcher (RIE) apparatus can be used to precisely control mesa depth by adjusting etch rate; when the chemical etching mode is used, the depth of the table top can be accurately controlled by adjusting the proportion of the etching solution and the etching time. For the ridge waveguide structure, the corrosion depth can be naturally corroded to an anti-corrosion layer by adopting chemical corrosion, and the ridge width range can be about 1-3 mu m, but the method is not limited to the method; for BH structures, the etching depth is usually as high as that of InP substrates, and the ridge width may be about 30 μm, but is not limited thereto.

Further, the method may further include:

forming an insulating layer 17 on sidewalls and bottoms of the first and second U-shaped trenches 21 and 22 and over the ohmic contact layer 16 except for the waveguide structure 20;

forming an upper electrode layer 18 in the first and second U-shaped trenches 21 and 22, above the waveguide structure 20 and above a portion of the top surface of the insulating layer 17;

the bottom surface of the epitaxial wafer is thinned, and a lower electrode layer 19 is formed on the bottom surface of the epitaxial wafer.

Note that, referring to fig. 10, a schematic diagram of a structure obtained after forming the insulating layer 17 according to an embodiment of the present disclosure is shown. As shown in fig. 10, the insulating layer 17 is formed at the bottom and sides of the first and second U-shaped grooves 21 and 22 while also being formed at the surface of the ohmic contact layer 16, but is not formed at the surface of the ohmic contact layer 16 included in the waveguide structure 20. At this time, the region above the waveguide structure 20 is a region corresponding to the current injection window, and, as shown in fig. 10, a region corresponding to the electrode window is formed between the insulating layers 17 (here, a region for forming the upper electrode layer 18 is mainly referred to).

Fig. 11 is a schematic view of the structure obtained after the formation of the upper electrode layer 18. As shown in fig. 11, the upper electrode layer 18 is formed entirely within the first U-shaped trench 21 and the second U-shaped trench 22, and is also formed over a portion of the top surface of the insulating layer 17.

Finally, the bottom surface of the epitaxial wafer is thinned, and a lower electrode layer 19 is formed on the bottom surface of the epitaxial wafer, resulting in the structure shown in fig. 5.

The material of the insulating layer 17 may be silicon dioxide (SiO ₂ ) The thickness of the insulating layer 17 may be about 2 μm.The materials of the upper electrode layer 18 and the lower electrode layer 19 may include metal materials such as Ti, pt, au, and the like, conductive materials, and the formation method may be evaporation, sputtering, and the like.

In forming the insulating layer 17, the insulating layer shown in fig. 10 is not necessarily directly obtained due to restrictions in process conditions. For example, in one implementation, as shown in fig. 12A, on the basis of fig. 8, first, a first initial insulating layer 17A is formed on the surface of the structure shown in fig. 8, as shown in fig. 12A, the first initial insulating layer 17A also covers the waveguide structure 20, and then the first initial insulating layer 17A above (including both sides of) the waveguide structure 20 is removed, thereby obtaining the structure shown in fig. 10.

Alternatively, as shown in fig. 12B, on the basis of fig. 8, the second initial insulating layer 17B is first formed. As shown in fig. 12B, the second initial insulating layer 17B completely fills the first U-shaped trench 21 and the second U-shaped trench 22. The second initial insulating layer 17B is then processed to obtain a current injection window, an electrode window.

Alternatively, the sacrificial layer may be formed first over the waveguide structure 20, then the insulating layer 17 may be formed on the sidewalls and bottoms of the first and second U-shaped trenches 21 and 22 and over the ohmic contact layer 16, and then the sacrificial layer may be removed to form the upper electrode layer 18.

Alternatively, after the formation of the ridge mesa waveguide structure 20, the SiO is grown using plasma enhanced chemical vapor deposition (Plasma Enhanced Chemical Vapor Deposition, PECVD) ₂ The insulating layer may have a thickness of about 2 μm. Then a current injection window is opened on the ridge by means of photoetching, etching and the like, and then SiO is deposited and grown on the surface of the chip _X Or SiN _X Removing the dielectric film on the ridge by photoetching and etching, and the like, overlaying an electrode window, and then adopting an evaporation and sputtering method to manufacture upper and lower metal electrodes (namely an upper electrode layer 18 and a lower electrode layer 19) with certain thickness, wherein the electrode material can be Ti, pt and Au.

That is, the embodiment of the present disclosure may form the insulating layer 17 and the upper electrode layer 18 in various ways, and is not limited to the several examples herein, and no limitation is made herein as to the specific forming manner.

Further, the optical coating surface is a front end surface of the semiconductor optical amplifier 10, and the method may further include:

an antireflection film is formed on the optical plating surface.

After the chip is dissociated, in order to reduce the end surface reflection, an optical film may be deposited on the same end surface of the light entering and exiting of the chip, so as to enhance the anti-reflection property and increase the light transmittance, where the optical film may be an anti-reflection film.

That is, in the finally obtained semiconductor optical amplifier 10, both ends of the U-shape of the waveguide structure 20 are the input end and the output end as the semiconductor optical amplifier 10, respectively, both of which are located on the optical plating surface of the semiconductor optical amplifier 10, and the waveguide structure 20 is inclined with respect to the optical plating surface.

In summary, in view of the shortcomings of the prior art, embodiments of the present disclosure provide a method for designing a semiconductor optical amplifier structure. The semiconductor optical amplifier adopts a U-shaped inclined bent waveguide structure, and an input end and an output end are arranged on the same end face. The epitaxial wafer is composed of a multi-layer epitaxial structure which is sequentially grown in an epitaxial mode, and specifically comprises a lower electrode layer, a substrate, a buffer layer, an active layer, an upper cladding layer, an ohmic contact layer, an insulating layer and an upper electrode layer.

The scheme does not adopt a traditional waveguide structure, but adopts an inclined U-shaped waveguide structure with a certain angle with the front end face of the chip, and then the U-shaped SiO is manufactured ₂ And finally, thinning the insulating layer to manufacture the lower metal electrode (namely, the lower electrode layer). The U-shaped waveguide is an inclined bent waveguide comprising a U-shaped turn, the inclination angle theta is an included angle between the normal line of the U-shaped waveguide structure and the light emergent end face, the range of theta is 0-18 degrees, the length of the single-side inclined waveguide can be recorded as L, the range of the single-side inclined waveguide is 500-3000 mu m, and the width range between the double-side waveguides of the U-shaped inclined waveguide structure is 250-2000 mu m; the end faces of the input end and the output end are the front end faces of the waveguides, and the end faces are the light inlet end faces and the light outlet end faces of the chips. In addition, the active layer corresponds to the U-shaped inclined waveguide structure in upper and lower positions to ensure the U-shapeAn active region exists directly below the angled waveguide; the active layer includes, but is not limited to, quantum well structures, bulk material structures, and the like.

In the preparation process, the corresponding epitaxial structure can be obtained by one or more MOCVD techniques, and meanwhile, siO can be used _X Or SiN _X And the like as a mask, and then a U-shaped inclined ridge type mesa waveguide structure is manufactured on a plane by means of photoetching and the like. SiO can be grown by chemical vapor deposition ₂ And an insulating layer, and opening a current injection window on the ridge by means of photoetching, etching and the like. The P-side electrode window can be etched by photoetching, etching and the like, and then the P-side electrode is manufactured by sputtering and the like. Finally, after the epitaxial wafer is thinned, the N-face electrode is manufactured through an evaporation and sputtering method, and a plurality of layers of anti-reflection films can be plated on the front end face of the chip.

According to the embodiment of the disclosure, the waveguide structure in the semiconductor optical amplifier is designed into a U shape, so that the input end and the output end of the semiconductor optical amplifier are positioned on the same end face of the semiconductor optical amplifier, and therefore, in the process of manufacturing a chip, only one optical film needs to be plated, the process steps are effectively reduced, the process flow is optimized, and the manpower and material resources are saved; in addition, the waveguide structure is inclined relative to the optical coating surface, so that resonance of light waves in the semiconductor optical amplifier can be effectively avoided, and the reduction of spectrum ripple waves is facilitated; further, the semiconductor optical amplifier with the structure has smaller volume, and is beneficial to integrated packaging with other devices.

In yet another embodiment of the present disclosure, reference is made to fig. 13, which illustrates a schematic structural diagram of a circuit system 130 provided by an embodiment of the present disclosure. As shown in fig. 13, the circuitry 130 includes the semiconductor optical amplifier 10 described in the previous embodiments. Thus, the performance of the circuitry 130 can be enhanced. The circuitry 130 may be any system, electronic device, circuit, etc. including a semiconductor optical amplifier, which is not particularly limited.

The foregoing description is only of the preferred embodiments of the present disclosure, and is not intended to limit the scope of the present disclosure.

It should be noted that in this disclosure, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one … …" does not exclude the presence of other like elements in a process, method, article, or apparatus that comprises the element.

The foregoing embodiment numbers of the present disclosure are merely for description and do not represent advantages or disadvantages of the embodiments.

The methods disclosed in the several method embodiments provided in the present disclosure may be arbitrarily combined without collision to obtain a new method embodiment.

The features disclosed in the several product embodiments provided in the present disclosure may be combined arbitrarily without conflict to obtain new product embodiments.

The features disclosed in the several method or apparatus embodiments provided in the present disclosure may be arbitrarily combined without any conflict to obtain new method embodiments or apparatus embodiments.

The foregoing is merely specific embodiments of the disclosure, but the protection scope of the disclosure is not limited thereto, and any person skilled in the art can easily think about changes or substitutions within the technical scope of the disclosure, and it is intended to cover the scope of the disclosure. Therefore, the protection scope of the present disclosure shall be subject to the protection scope of the claims.

Claims

1. A semiconductor optical amplifier, comprising a waveguide structure, the waveguide structure being U-shaped, wherein:

2. The semiconductor optical amplifier according to claim 1, wherein the waveguide structure includes an input portion, a turning portion, and an output portion, the input portion and the output portion being linear, the turning portion being curved, the turning portion being connected to the input portion and the output portion, respectively, the input portion and the output portion being parallel; wherein:

the included angle between the input part and the normal line of the optical coating surface is 0-18 degrees.

3. The semiconductor optical amplifier according to claim 2, wherein a distance from the input end to a tangent line of an apex of the turning portion is: 500-3000 μm, the distance from the output end to the tangent line of the vertex of the turning part is: 500-3000 μm, the distance between the input portion and the output portion being: 250-2000 mu m;

4. The semiconductor optical amplifier according to claim 1, wherein the semiconductor optical amplifier comprises a lower electrode layer, a substrate layer, a buffer layer, an active layer, an anti-corrosion layer, an upper cladding layer, an ohmic contact layer, an insulating layer, and an upper electrode layer, which are stacked in this order;

wherein the active layer is located at least below the waveguide structure.

5. The semiconductor optical amplifier according to claim 4, wherein a first U-shaped trench and a second U-shaped trench are formed in the ohmic contact layer and the upper cladding layer, and the second U-shaped trench is located at an outer periphery of the first U-shaped trench, the waveguide structure including the upper cladding layer and the ohmic contact layer located between the first U-shaped trench and the second U-shaped trench; wherein:

6. The semiconductor optical amplifier according to any one of claims 1 to 5, wherein the optical coating surface is a front end surface of the semiconductor optical amplifier, and the optical coating surface is coated with at least one antireflection film.

7. A method of fabricating a semiconductor optical amplifier, the method comprising:

8. The method of claim 7, wherein providing the epitaxial wafer comprises:

9. The method of claim 8, wherein forming a waveguide structure within the waveguide layer comprises:

10. The method according to claim 9, wherein the method further comprises:

11. The method according to any one of claims 7 to 10, wherein the optical plating surface is a front end surface of the semiconductor optical amplifier, the method further comprising: