CN115995759B - Multi-wavelength laser and method of making the same - Google Patents

Abstract

The invention provides a multi-wavelength laser, which is applied in the field of semiconductor technology. The multi-wavelength laser includes at least one laser array unit, the laser array unit includes an SOI structure and a III-V semiconductor laser structure, and the SOI structure includes a silicon substrate , a BOX layer and a top silicon layer, a silicon waveguide structure is etched in the top silicon layer, a REC silicon nitride dielectric grating is etched on the side of the silicon waveguide structure, and the III-V semiconductor laser structure includes an N-type InP Layer, multi-quantum well MQWs layer, P-type InP layer, III-V family ridge waveguide, P-face metal electrode and N-face metal electrode, wherein, the silicon waveguide structure and the III-V family ridge waveguide are aligned in the same direction allow. The invention also provides a manufacturing method of a multi-wavelength laser, the manufacturing process is simple, and the wavelength of each channel is easy to precisely control.

Description

Multi-wavelength laser and method of making the same

technical field

The invention relates to the technical field of semiconductors, in particular to a multi-wavelength laser and a manufacturing method thereof.

Background technique

In recent years, with the continuous emergence of emerging Internet applications such as virtual reality and cloud computing, people have put forward higher and higher requirements for the performance of communication systems such as communication rate, communication capacity and communication bandwidth. At the same time, massive data interaction also puts forward high-speed and high-bandwidth requirements for the interconnection network of the data center. The wavelength division multiplexing and dense wavelength division multiplexing technologies applied to optical communication systems can meet people's ever-increasing Internet business needs. Multi-wavelength narrow-linewidth semiconductor laser array chip light source has received more and more attention as the core optoelectronic device in wavelength division multiplexing and dense wavelength division multiplexing systems. The semiconductor laser array chip has become a better solution for multi-wavelength array light sources due to its advantages of compact structure, stable performance and suitable for monolithic integration. However, there are still some problems in the multi-wavelength laser array scheme, such as complex fabrication process and difficult precise control of the wavelength of each channel.

Contents of the invention

The main purpose of the present invention is to provide a multi-wavelength laser and its manufacturing method, which aims to solve the technical problems in the prior art that the multi-wavelength laser has a complicated manufacturing process and the wavelength of each channel is difficult to be accurately controlled.

In order to achieve the above object, the first aspect of the embodiment of the present invention provides a multi-wavelength laser, including at least one laser array unit, and the laser array unit includes:

The SOI structure includes a silicon substrate, a BOX layer and a top silicon layer, a silicon waveguide structure is etched in the top silicon layer, and a REC silicon nitride dielectric grating is etched laterally of the silicon waveguide structure;

III-V group semiconductor laser structure, including N-type InP layer, multiple quantum well MQWs layer, P-type InP layer, III-V group ridge waveguide, P-side metal electrode and N-side metal electrode;

Wherein, the silicon waveguide structure and the III-V group ridge waveguide are aligned along the same direction.

In an embodiment of the present invention, the silicon waveguide structure is a strip silicon waveguide or a ridge silicon waveguide.

In an embodiment of the present invention, the wavelengths of laser light output by the REC silicon nitride dielectric gratings in each of the laser array units are different.

In an embodiment of the present invention, the REC silicon nitride dielectric grating has a mode selection structure, and the mode selection structure is used to control the excitation of the ±1st order resonance peak of the REC silicon nitride dielectric grating by changing the sampling period. The emission wavelength can be used to obtain output light of different wavelengths.

In an embodiment of the present invention, the III-V semiconductor laser structure and the SOI structure are mixed and integrated by bonding.

In an embodiment of the present invention, the at least one laser array unit is arranged in parallel.

In an embodiment of the present invention, the III-V group ridge waveguide is a multi-layer epitaxial structure, and the multi-layer epitaxial structure includes three wedge-shaped waveguide structures with different tapers, and the three wedge-shaped waveguide structures with different tapers are respectively engraved with etch on the N-type InP layer, the MQWs layer and the P-type InP layer.

The second aspect of the embodiment of the present invention provides a method for manufacturing a multi-wavelength laser, including:

Prepare an SOI structure, the SOI structure includes a silicon waveguide structure, and the side of the silicon waveguide structure is etched with a REC silicon nitride dielectric grating;

Preparation of semiconductor laser structure;

mixing and integrating the semiconductor laser structure and the SOI structure by bonding to obtain a preliminary laser;

Preparing III-V group ridge waveguides on the semiconductor laser structure of the preparation laser, and aligning the silicon waveguide structure and the III-V group ridge waveguide along the same direction.

In an embodiment of the present invention, the preparation of the SOI structure includes:

Sequentially grow silicon substrate, BOX layer and top silicon layer;

etching the top silicon layer to form a silicon waveguide structure;

The REC silicon nitride dielectric grating is etched laterally on the silicon waveguide structure.

In an embodiment of the present invention, the preparatory laser structure includes an N-type InP layer, a multi-quantum well MQWs layer, a P-type InP layer, a III-V family ridge waveguide, a P-face metal electrode and an N-face metal electrode. The preparation of III-V group ridge waveguides on the semiconductor laser structure of the preparation laser includes:

Etching an InP ridge waveguide on the P-type InP layer, and etching the first wedge-shaped waveguide coupler region;

Etching a second wedge-shaped waveguide coupler region in the multi-quantum well MQWs layer;

Etching a third wedge-shaped waveguide coupler region on the P-type InP layer;

Wherein, the taper of the first wedge-shaped waveguide coupler region, the second wedge-shaped waveguide coupler region and the third wedge-shaped waveguide coupler region are different.

The multi-wavelength laser proposed by the present invention constructs a lateral REC silicon nitride dielectric grating by etching the silicon nitride medium, and changing the micron-level sampling period can precisely control the ±1-order resonance peak of the nano-level REC, making the lasing wavelength more stable Reliable, so that the laser lasing wavelength of each channel in the laser array meets specific requirements, which is conducive to meeting the high-speed and high-bandwidth requirements of the communication system. At the same time, the optical loss of the silicon nitride dielectric material is very low, and it can better suppress the lateral direction The diffusion of carriers is conducive to improving the overall performance of the device, the preparation process is simple, and the wavelength of each channel is easy to accurately control.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only These are some embodiments of the present invention. For those skilled in the art, other drawings can also be obtained according to these drawings without creative work.

FIG. 1 is a schematic structural diagram of a laser array unit provided by an embodiment of the present invention;

Fig. 2 is a schematic structural diagram of a SOI structure lateral REC silicon nitride dielectric grating provided by an embodiment of the present invention;

3 is a schematic structural diagram of a III-V ridge waveguide provided by an embodiment of the present invention;

FIG. 4 is a schematic structural diagram of a multi-wavelength laser provided by an embodiment of the present invention;

5 is a schematic diagram of the spectrum of an analog 8-channel multi-wavelength laser provided by an embodiment of the present invention;

FIG. 6 is a schematic flowchart of a method for manufacturing a multi-wavelength laser provided by an embodiment of the present invention.

Detailed ways

In order to make the purpose, features and advantages of the present invention more obvious and understandable, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described The embodiments are only some of the embodiments of the present invention, but not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative efforts belong to the protection scope of the present invention.

Please refer to FIG. 1 . FIG. 1 is a schematic structural diagram of a laser array unit provided by an embodiment of the present invention.

As shown in FIG. 1 , the laser array unit includes an SOI structure 1 and a III-V group semiconductor laser structure 2 . The SOI structure 1 includes a silicon substrate 105, a BOX layer 104, and a top silicon layer 103. A silicon waveguide structure 101 is etched in the top silicon layer 103 to realize light transmission. The side of the silicon waveguide structure 101 is etched with REC silicon nitride. Dielectric grating 102. The III-V group semiconductor laser structure 2 includes an N-type InP layer 201, a multi-quantum well MQWs layer 202, a P-type InP layer 203, a III-V group ridge waveguide 206, a P-face metal electrode 204, and an N-face metal electrode 205, wherein, The silicon waveguide structure 101 is aligned in the same direction as the III-V ridge waveguide 206 .

In an embodiment, the III-V semiconductor laser structure 2 and the SOI structure 1 are mixed and integrated by bonding. Bonding methods include direct bonding, metal bonding, and dielectric bonding.

In one embodiment, the silicon substrate 105 serves to support the entire multi-wavelength laser.

In one embodiment, the thickness of the BOX layer 104 is generally greater than 1 um. The function of the BOX layer is to isolate the silicon waveguide structure 101 from the silicon substrate 105 and prevent the optical modes transmitted in the silicon waveguide structure 101 from leaking to the silicon substrate 105 .

Please refer to FIG. 2 . FIG. 2 is a schematic structural diagram of a SOI structure lateral REC silicon nitride dielectric grating provided by an embodiment of the present invention.

As shown in Figure 2, after the silicon waveguide structure 101 is etched, a silicon nitride dielectric film with a certain thickness is deposited on the top silicon layer 103, and then electron beam lithography and reactive ion etching (Reactive Ion Etching, RIE) are used. The technology fabricates a Reconstruction Equivalent Chirp (REC) silicon nitride dielectric grating 102 on the side of the silicon waveguide structure 101 to achieve single-mode output.

Wherein, the silicon waveguide structure 101 is a strip silicon waveguide or a ridge silicon waveguide. The silicon waveguide structure 101 has a width of several um and a depth of hundreds of nm.

In one embodiment, the REC silicon nitride dielectric grating 102 has a mode selection structure, and the mode selection structure is used to adjust the lasing wavelength of the ±1st-order resonance peak of the REC silicon nitride dielectric grating 102 by changing the sampling period to obtain different wavelength of output light.

In one embodiment, the N-type InP layer 201 includes an N-type InP ohmic contact layer and an N-type InGaAsP/InP bonding layer.

In one embodiment, the multi-quantum well MQWs layer 202 is made of AlGaInAs material, and the AlGaInAs material is undoped, which is used for recombination of carriers and generation of photons. In the present invention, the use of AlGaInAs material can make the temperature tolerance of the laser strong, and has a large conduction band difference (ΔEc=0.72ΔEg), and a higher conduction band difference can ensure excess carriers such as Electrons are not easy to overflow to the barrier region and the separation confinement layer across the well region.

In one embodiment, the P-type InP layer 203 includes a P-type InP buffer layer, an InGaAs etch stop layer, a P-type InGaAs ohmic contact layer, and a P-type AlGaInAs upper separation confinement layer (SCH, Separate Confinement Heterostructure). The P-type InP buffer layer is used to match the lattice and reduce the lattice mismatch. The InGaAs etch stop layer is used as a chemical reaction stop layer when removing the InP substrate and the P-type InP buffer layer. The function of the P-type InGaAs ohmic contact layer is to reduce the contact surface resistance, so that the voltage is mainly concentrated on the active layer instead of being consumed at the electrode connection due to thermal effects. The separation confinement layer on the P-type AlGaInAs is used to confine the expansion of the fundamental mode field.

Please refer to FIG. 3 . FIG. 3 is a schematic structural diagram of a III-V group ridge waveguide provided by an embodiment of the present invention.

As shown in FIG. 3 , the III-V group ridge waveguide 206 is a multilayer epitaxial structure, and the multilayer epitaxial structure includes three wedge-shaped waveguide structures with different tapers, and the three wedge-shaped waveguide structures with different tapers are respectively etched on the N-type InP Layer 201, multiple quantum well MQWs layer 202 and P-type InP layer 203. That is, as shown in FIG. 3 , the first wedge-shaped waveguide coupler region 209 , the second wedge-shaped waveguide coupler region 208 and the third wedge-shaped waveguide coupler region 207 .

Please refer to FIG. 4 , which is a schematic structural diagram of a multi-wavelength laser provided by an embodiment of the present invention.

As shown in FIG. 4 , the multi-wavelength laser includes at least one laser array unit, and the at least one laser array unit is arranged in parallel. The REC silicon nitride dielectric gratings 102 in each laser array unit output laser light with different wavelengths, that is, the REC silicon nitride dielectric gratings 102 in the at least one laser array unit are different from each other and have different sampling periods. for outputting laser light of different wavelengths.

In one embodiment, the output wavelength of each laser array unit is C-band or L-band.

In one embodiment, the output wavelength interval of two adjacent lasers is 0.8nm or 0.4nm.

Please refer to FIG. 5 . FIG. 5 is a schematic diagram of a simulated 8-channel multi-wavelength laser spectrum provided by an embodiment of the present invention.

As shown in Figure 5, the output wavelengths are 8 wavelengths with a wavelength interval of 0.8nm around 1550nm. The sampling period is 7179nm, 7295nm, 7414nm, 7537nm, 7664nm, 7795nm, 7931nm and 8072nm, by only changing the sampling period to regulate the lasing wavelength of the ±1st harmonic peak of the REC silicon nitride dielectric grating 102, the sampling period is in the order of several microns level, and the period of the seed grating is on the order of hundreds of nanometers. It can be seen that adjusting the ±1-order resonant peak of the REC silicon nitride dielectric grating 102 by changing the sampling period is more robust than adjusting the 0-order resonant peak through the seed grating period. The emission wavelength is also more stable and reliable.

Please refer to FIG. 6. FIG. 6 is a schematic flowchart of a method for manufacturing a multi-wavelength laser provided by an embodiment of the present invention. The method mainly includes the following steps:

S401 , preparing an SOI structure 1 , the SOI structure 1 includes a silicon waveguide structure 101 , and a REC silicon nitride dielectric grating 102 is etched laterally of the silicon waveguide structure 101 .

S402, preparing a semiconductor laser structure.

S403 , mixing and integrating the semiconductor laser structure and the SOI structure 1 by bonding to obtain a preliminary laser.

S404 , preparing a III-V group ridge waveguide 206 on the semiconductor laser structure of the preparation laser, and aligning the silicon waveguide structure 101 and the III-V group ridge waveguide 206 along the same direction.

Wherein, the silicon waveguide structure 101 and the group III-V ridge waveguide 206 are aligned along the vertical direction in FIG. 1 , and are coupled to each other through the principle of evanescent wave coupling.

In one embodiment, preparing the SOI structure 101 in S401 includes: growing the silicon substrate 105, the BOX layer 104, and the top silicon layer 103 in sequence; etching the top silicon layer 103 to form the silicon waveguide structure 101; The REC silicon nitride dielectric grating 102 is etched.

It can be understood that the silicon waveguide structure 101 and the REC silicon nitride dielectric grating 102 are fabricated on the SOI structure 1 before bonding, and the III-V group ridge waveguide 206 is fabricated on the bonded laser array unit.

In one embodiment, the preliminary laser structure includes an N-type InP layer 201, a multi-quantum well MQWs layer 202, a P-type InP layer 203, a III-V family ridge waveguide 206, a P-face metal electrode 204, and an N-face metal electrode 205, The preparation of the III-V group ridge waveguide 206 on the semiconductor laser structure of the preparation laser includes: etching the InP ridge waveguide on the P-type InP layer 203, and etching the first wedge-shaped waveguide coupler region 209; The second wedge-shaped waveguide coupler region 208 is etched out of the quantum well MQWs layer 202; the third wedge-shaped waveguide coupler region 207 is etched out in the P-type InP layer 203; wherein, the first wedge-shaped waveguide coupler region 209, the second The taper of the second wedge waveguide coupler region 208 and the region of the third wedge waveguide coupler 207 are different.

In the present invention, firstly, the III-V group ridge waveguide 206 is etched by photolithography and etching process to form a P-type injection region and a carrier channel, and at the same time, the first wedge-shaped waveguide coupler region 207 is etched. . Then, the SCH layer in the multi-quantum well MQWs 202 and the P-type InP layer 203 is photolithographically etched to expose the N-type InP layer 201 , and the second wedge-shaped waveguide coupler region 208 is etched at the same time. Finally, photolithography and etching remove the N-type InP layer 201 area on the silicon waveguide structure outside the wedge-shaped waveguide coupler area, and isolate the silicon-based hybrid integrated lasers from each other to avoid electrical crosstalk between them. Three wedge-shaped waveguide coupler regions 209, etched III-V ridge waveguides 206.

Above, the three-step dry etching process etches three wedge-shaped waveguide structures with different tapers as shown in Figure 3, which can gradually convert the mode of the multi-wavelength laser into the mode transmitted in the silicon waveguide, improve the coupling efficiency and reduce the loss .

Further, the electrode window is opened by photolithography, the PN electrode is drawn out, the coplanar metal TiAu is grown by magnetron sputtering technology, and the metal is etched by photolithography to form the PN electrode region. Wherein, the N-face metal electrode 205 is TiAu, located on the N-type ohmic contact layer, and the P-face metal electrode 204204 is TiAu, located on the P-type ohmic contact layer, and the N-face metal electrode 205 and the P-face metal electrode 204 are used for electric current Injection, which belongs to the coplanar electrode.

Apparently, the drawings in the following description are only some embodiments of the present invention, and those skilled in the art can obtain other drawings according to these drawings without creative efforts.

Those of ordinary skill in the art should understand that: the discussion of any of the above embodiments is exemplary only, and is not intended to imply that the scope of the present invention (including claims) is limited to these examples; under the idea of the present invention, the above embodiments or Combinations between technical features in different embodiments are also possible, steps may be carried out in any order, and there are many other variations of the different aspects of the invention as described above, which are not presented in detail for the sake of brevity.

Additionally, where specific details have been set forth to describe example embodiments of the invention, it will be apparent to those skilled in the art that the invention may be practiced without or with variations from these specific details . Accordingly, these descriptions should be regarded as illustrative rather than restrictive.

Although the invention has been described in conjunction with specific embodiments of the invention, many alternatives, modifications and variations of those embodiments will be apparent to those of ordinary skill in the art from the foregoing description.

Embodiments of the present invention are intended to embrace all such alterations, modifications and variations that fall within the broad scope of the appended claims. Therefore, any omissions, modifications, equivalent replacements, improvements, etc. within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims (9)

1. A multi-wavelength laser, is characterized in that, comprises at least one laser array unit, and described laser array unit comprises: The SOI structure includes a silicon substrate, a BOX layer and a top silicon layer, a silicon waveguide structure is etched in the top silicon layer, and a REC silicon nitride dielectric grating is etched laterally of the silicon waveguide structure; III-V group semiconductor laser structure, including N-type InP layer, multiple quantum well MQWs layer, P-type InP layer, III-V group ridge waveguide, P-side metal electrode and N-side metal electrode; Wherein, the silicon waveguide structure and the III-V group ridge waveguide are aligned in the same direction; the III-V group ridge waveguide is a multi-layer epitaxial structure, and the multi-layer epitaxial structure includes three wedge-shaped waveguides with different tapers structure, the three wedge-shaped waveguide structures with different tapers are respectively etched on the N-type InP layer, the MQWs layer and the P-type InP layer. 2. The multi-wavelength laser according to claim 1, wherein the silicon waveguide structure is a strip silicon waveguide or a ridge silicon waveguide. 3 . The multi-wavelength laser according to claim 1 , wherein the wavelengths of laser light output by the REC silicon nitride dielectric gratings in each of the laser array units are different. 4 . 4. The multi-wavelength laser according to claim 1 or 3, wherein the REC silicon nitride dielectric grating has a mode selection structure, and the mode selection structure is used to control the REC nitride by changing the sampling period. The lasing wavelength of the ±1st-order resonance peak of the silicon dielectric grating is used to obtain output light of different wavelengths. 5. The multi-wavelength laser according to claim 4, wherein the III-V group semiconductor laser structure and the SOI structure are mixed and integrated by bonding. 6. The multi-wavelength laser according to claim 1, wherein the at least one laser array unit is arranged in parallel. 7. A method for manufacturing a multi-wavelength laser, comprising: Prepare an SOI structure, the SOI structure includes a silicon waveguide structure, and the side of the silicon waveguide structure is etched with a REC silicon nitride dielectric grating; Prepare a III-V group semiconductor laser structure, the III-V group semiconductor laser structure includes an N-type InP layer, a multi-quantum well MQWs layer, a P-type InP layer, a III-V group ridge waveguide, a P-face metal electrode and an N-face metal electrode; mixing and integrating the III-V semiconductor laser structure and the SOI structure by bonding to obtain a preliminary laser; Prepare a III-V group ridge waveguide on the III-V group semiconductor laser structure of the preparation laser, and align the silicon waveguide structure and the III-V group ridge waveguide in the same direction; the III -The Group V ridge waveguide is a multi-layer epitaxial structure, the multi-layer epitaxial structure includes three wedge-shaped waveguide structures with different tapers, and the three wedge-shaped waveguide structures with different tapers are respectively etched on the N-type InP layer, the on the MQWs layer and the P-type InP layer. 8. The method for manufacturing a multi-wavelength laser according to claim 7, wherein said preparation of an SOI structure comprises: Sequentially grow silicon substrate, BOX layer and top silicon layer; etching the top silicon layer to form a silicon waveguide structure; The REC silicon nitride dielectric grating is etched laterally on the silicon waveguide structure. 9. the manufacture method of multi-wavelength laser according to claim 7, is characterized in that, described preliminary laser structure comprises N-type InP layer, multiple quantum well MQWs layer, P-type InP layer, III-V group ridge waveguide, P Surface metal electrodes and N-face metal electrodes, the preparation of the III-V group ridge waveguide on the semiconductor laser structure of the preparation laser includes: Etching an InP ridge waveguide on the P-type InP layer, and etching the first wedge-shaped waveguide coupler region; Etching a second wedge-shaped waveguide coupler region in the multi-quantum well MQWs layer; Etching a third wedge-shaped waveguide coupler region on the P-type InP layer; Wherein, the taper of the first wedge-shaped waveguide coupler region, the second wedge-shaped waveguide coupler region and the third wedge-shaped waveguide coupler region are different.

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