KR20150048017A

KR20150048017A - Superluminescent diode and method for implementing the same

Info

Publication number: KR20150048017A
Application number: KR1020140055793A
Authority: KR
Inventors: 오수환; 김민수
Original assignee: 한국전자통신연구원
Priority date: 2013-10-24
Filing date: 2014-05-09
Publication date: 2015-05-06
Also published as: KR102049342B1

Abstract

A super luminescent diode and its implementation are disclosed. A method of fabricating a superluminescent diode (SLD) of a wavelength tunable laser comprises growing a first epitaxial layer on top of a semi-insulating substrate, regenerating the butt based on the first epitaxial layer, forming a tapered SSC (spot size converter) on the butt layer, forming an optical waveguide in the active region based on the first epi layer and in the SSC region based on the tapered SSC, And forming a p-type electrode and an n-type electrode.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a super luminescent diode and a super luminescent diode,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to optical communication, and more particularly, to a super luminescent diode which is a light source of a tunable laser and an implementation method thereof.

In order to realize an economical wavelength division multiplexing (WDM) subscriber line system, it is essential to develop a stable and economical light source. In particular, since the WDM subscriber line system has a specific wavelength assigned to each subscriber, a wavelength-independent light source capable of providing the same light source for each subscriber regardless of a designated wavelength should be studied.

As a research of this colorless light source, researches on wavelength-locked laser diode (FP-LD), reflective semiconductor optical amplifier (RSOA) and planar lightwave circuit (PLC) -ECL (external cavity laser) Is actively proceeding.

FP-LD (Febry-Perot Laser Diode) among laser diodes used as a light emitting device for optical communication is widely used because it is easy to manufacture and low in price. However, it is difficult to apply FP-LD to long-haul transmission or WDM transmission due to generation of plural seed modes. As an alternative, there is a DFB-LD (Distributed Feed Back-Laser Diode) in which the line width is narrow and the single mode characteristic is stably outputted, but the manufacturing process is difficult and the cost is high.

As an alternative, various types of external cavity lasers have been proposed. The external resonator laser has the characteristic of oscillating in a single mode by overlapping the mode of the FP-LD oscillating in the multi-mode and the mode of the external resonator. The wavelength of the external resonator laser is higher than that of the conventional DFB-LD (Distributed Feed Back- Temperature stability. However, most of the external resonator laser structures are complicated in structure using optical fiber bragg gratings or require high precision in fabrication, which makes it difficult to apply them to low cost commercial products.

A first object of the present invention is to provide a method of implementing a superluminescent diode (SLD) which is a light source of a tunable laser.

A second object of the present invention is to provide a superluminescent diode (SLD) which is a light source of a tunable laser.

According to an aspect of the present invention, there is provided a method of fabricating a superluminescent diode (SLD), which is a light source of a tunable laser, including: forming a first epitaxial layer , Growing a butt on the first epilayer, forming a tapered SSC (spot size converter) on the re-grown butt layer, forming an active region based on the first epilayer, Forming an optical waveguide in the SSC region based on the tapered SSC, forming a RWG waveguide on the optical waveguide, and forming a p-type electrode and an n-type electrode do.

In one embodiment, the first epi layer may be formed by sequentially laminating an n-InP buffer layer, an InGaAsP passive waveguide layer, an n-InP lower clad layer, a multiple quantum well active layer, and a p-InP upper clad layer.

In one embodiment, the step of regrowing the butt based on the first epi layer may include depositing a SiNx thin film on top of the p-InP upper cladding layer, depositing the SiNx thin film, the p-InP upper cladding layer, Etching the multi-quantum well active layer, forming an InGaAsP waveguide layer in the etched region, and growing a p-InP layer on the InGaAsP waveguide layer.

In one embodiment, the step of forming tapered SSC in the regrown butt layer may include partially etching the InGaAsP waveguide layer and the p-InP layer and forming a tapered SSC on top of the p-InP layer .

In one embodiment, the step of forming the optical waveguide based on the first epilayers and the SSC may include forming the active layer including the non-etched SiNx thin film, the p-InP upper cladding layer, And etching the SSC region partially before the n-InP buffer layer.

In one embodiment, the step of forming the RWG waveguide on the optical waveguide includes the steps of laminating a current blocking layer on the right and left sides of the optical waveguide, laminating a cladding layer on top of the optical waveguide and the current blocking layer, Laminating an ohmic layer on top of the layer, and selectively etching the current blocking layer, the clad layer, and the ohmic layer.

In one embodiment, the active region and the SSC region may be implemented with a planar buried heterostructure (PBH) structure.

In one embodiment, the SSC region may be implemented to bend 5 to 15 degrees.

In one embodiment, the RWG waveguide may be implemented to have a width of 9-11 [mu] m.

In one embodiment, a method of implementing a superluminescent diode (SLD), which is a light source of a tunable laser, further includes implementing a p-type electrode of a phase control region that is an additional electrode in the SSC region to control the refractive index of the optical signal can do.

According to an aspect of the present invention, there is provided a superluminescent diode (SLD), which is a light source of a tunable laser, including a first epitaxial layer formed on a top of a semi-insulating substrate, Butt formed on the basis of the epi layer, a tapered SSC (spot size converter) formed on the butt layer, an active region based on the first epi layer, and a light formed based on the SSC region based on the tapered SSC An RWG waveguide formed on the optical waveguide, a p-type electrode formed on the RWG waveguide, and an n-type electrode formed on a side of the RWG waveguide region.

In one embodiment, the first epi layer includes an n-InP buffer layer, an InGaAsP passive waveguide layer, an n-InP bottom cladding layer, a multiple quantum well active layer, and a p-InP upper cladding layer sequentially stacked from the top of the SI substrate can do.

In one embodiment, the butt layer is formed on the p-InP upper cladding layer and the region where the multiple quantum well active layer is etched, and the butt layer is formed on the n-InP lower cladding layer of the etched region An InGaAsP waveguide layer, and a p-InP layer formed on the InGaAsP waveguide layer.

In one embodiment, the RWG waveguide may include a current blocking layer formed on the right and left sides of the optical waveguide, a cladding layer formed on the optical waveguide and the current blocking layer, and an ohmic layer formed on the cladding layer.

In one embodiment, the RWG waveguide may have a width of 9-11 [mu] m.

In one embodiment, the SLD may further include a p-type electrode of the phase control region on the SSC region, which is an additional electrode for adjusting the refractive index of the optical signal.

As described above, when the method of implementing the super luminescent diode according to the embodiment of the present invention is used, a PLC-ECL using a PBH-SLD structure capable of operating at 10G bps or more is used as a light source, And a wavelength tunable external resonant laser operating at 10 Gbps can be realized.

1 and 2 are conceptual views illustrating a method of manufacturing an SLD according to an embodiment of the present invention.
3 is a conceptual diagram illustrating an SLD according to an embodiment of the present invention.
4 is a conceptual view showing a cross-sectional view of an active region of an SLD according to an embodiment of the present invention.
5 is a conceptual diagram showing a cross section of an SSC region according to an embodiment of the present invention.
6 is a conceptual diagram illustrating an SLD to which a phase control area according to an embodiment of the present invention is added.
7 is a conceptual diagram illustrating an external resonant laser based on an SLD according to an embodiment of the present invention.
8 is a conceptual diagram illustrating an external resonant laser based on an SLD according to an embodiment of the present invention.

While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail. It should be understood, however, that the invention is not intended to be limited to the particular embodiments, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention. Like reference numerals are used for like elements in describing each drawing.

The terms first, second, etc. may be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the first component may be referred to as a second component, and similarly, the second component may also be referred to as a first component. And / or < / RTI > includes any combination of a plurality of related listed items or any of a plurality of related listed items.

It is to be understood that when an element is referred to as being "connected" or "connected" to another element, it may be directly connected or connected to the other element, . On the other hand, when an element is referred to as being "directly connected" or "directly connected" to another element, it should be understood that there are no other elements in between.

The terminology used in this application is used only to describe a specific embodiment and is not intended to limit the invention. The singular expressions include plural expressions unless the context clearly dictates otherwise. In the present application, the terms "comprises" or "having" and the like are used to specify that there is a feature, a number, a step, an operation, an element, a component or a combination thereof described in the specification, But do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, or combinations thereof.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Hereinafter, the same reference numerals will be used for the same constituent elements in the drawings, and redundant explanations for the same constituent elements will be omitted.

Recently, a wavelength-locked Fabry-Perot laser diode (FP-LD), a reflective semiconductor optical amplifier (RSOA), a planar lightwave circuit (PLC) -ECL (external cavity laser) And so on.

The re-modulation structure using FP-LD and RSOA is dependent not only on the characteristics of the injected light source but also has a disadvantage that the data rate at which direct modulation is possible is limited to 1.25 Gbps. In this regard, PLC-ECL, which is economical and capable of direct modulation over 2.5Gbps, is widely used as the light source of the ultimate WDM optical network. The PLC-ECL may have a structure in which gratings are formed on silica and polymer waveguides formed on a silicon substrate, and semiconductor lasers as a light source are hybrid-integrated.

The semiconductor laser, which is the light source of the PLC-ECL, should not oscillate at less than 0.1% of the reflectivity of the emitting surface, and must have a high output at low current operation. Therefore, FP-LD and SLD (superluminescent diode) may be the light source satisfying these conditions. In general, an SLD having a wide bandwidth is mainly used as a light source of a PLC-ECL.

A typical SLD is fabricated by tilting the active layer or optical waveguide at an angle between 5 and 15 degrees to reduce the reflectivity of the outgoing cross-section. When the active layer or the optical waveguide is tilted at an angle of 5 to 15 degrees, the reflectivity of the outgoing cross-section can be reduced, but it may not be suitable for use as a light source for WDM-PON due to an increase in threshold current and an increase in operation current. Therefore, in order to overcome this incompatibility, studies are underway to make the SLD a light source having the characteristic of about the FP-LD which is anti-reflection and highly reflective coating.

In the embodiment of the present invention, the PLC-ECL implemented using the improved SLD and the improved SLD as the light source is posted. Hereinafter, a method of implementing a superluminescent diode (SLD), which is a light source coupled to an external cavity of a PLC-based external resonator, will be described. The tunable laser of the present invention can operate at an operating speed of 10 Gbps or more using an SLD implemented to operate at 10 Gbps or more.

Hereinafter, an SLD according to an embodiment of the present invention will be described on the assumption that a structure using an Si-InP substrate capable of operating at a low current as well as having excellent FFP (far field pattern) characteristics for convenience of explanation is used. However, the SLD according to the embodiment of the present invention may be realized not only by using a Si-InP substrate but also by using a ridge waveguide (RWG) structure or a Fe-doped current blocking layer.

1 and 2 are conceptual views illustrating a method of manufacturing an SLD according to an embodiment of the present invention.

Referring to FIG. 1, a first epitaxial layer is grown (step S110).

In order to fabricate the SLD, a first epitaxial layer can be grown. In the first epi layer, an n-InP buffer layer 12, an InGaAsP passive waveguide layer 13, an n-InP lower cladding layer 14, a multiple quantum well active layer 15, a p-InP The upper clad layer 16 can be sequentially grown.

The Butt layer is re-grown (step S120).

In step S120, the butt layer can be regrowth grown. First, a SiNx thin film 17 can be deposited on the top of the p-InP upper cladding layer 16. [ Except for the SiNx thin film 17 located in a part of the deposited SiNx thin film, the deposited SiNx thin film located in the remaining area can be etched. A part of the region which is not etched corresponds to an active region to be described later, and a part of the region to be etched may correspond to a later-described SSC region.

In addition, the p-InP layer 16 and the multiple quantum well active layer 15 at the bottom of the etched SiNx thin film can be further etched. After the SiNx thin film 17, the p-InP layer 16 and a part of the multiple quantum well active layer 15 are etched, an InGaAsP waveguide layer 18 and a p-InP layer 19 are formed at the top of the etched region Can grow. The InGaAsP waveguide layer 18 and the p-InP layer 19 can be expressed as a butt regrowth layer.

To form a spot size converter (SSC) (step S130).

In step S130, the SSC 20 may be formed on the butt regrowth layer posted in step S120. The butt regrowth layer may be etched to create the SSC region. The n-InP lower clad layer 14, the InGaAsP waveguide layer 18 and a part of the p-InP layer 19 can be etched so that the SSC can be formed. butt regrowth layer may be tapered from 1.5 [mu] m to less than 0.2 [mu] m.

Referring to FIG. 2, an optical waveguide is formed (step S140).

In step S140, the optical waveguide layer 21 may be formed by selectively etching portions other than the optical waveguide layer in order to form the optical waveguide layer 21 in the active region and the SSC region. The active region may be a region in which the SiNx thin film 17, the p-InP layer 16, and the multiple quantum well active layer 15 are not etched in step S120. The SSC region may be an area where the SSC is formed. After the optical waveguide layer 21 is formed, the passive waveguide layer 13 is etched by a selective etching method in order to increase coupling efficiency of the light to be guided. The width of the passive waveguide layer may be 2 to 9 占 퐉. The far field pattern (FFP) of the SLD can be changed according to the width of the passive waveguide layer 13. [ The width of the layer may vary depending on the shape of the SLD.

The optical waveguide can be formed in the active region and the SSC region. The optical waveguide can be produced with a width of, for example, 1 to 1.5 mu m. The optical waveguide located in the active region is referred to as an active region optical waveguide, and the optical waveguide located in the SSC region is referred to as an SSC region optical waveguide.

After the current blocking layers are laminated, the cladding layer and the ohmic layer are laminated in order, and then an RWG waveguide is formed (step S150).

The p-InP current blocking layer 22 and the n-InP current blocking layer 23, which are current blocking layers, may be formed on the upper portion of the optical waveguide formed on the basis of step S140. Next, the p-InP cladding layer 24 and the p + -InGaAs ohmic layer 25 can be grown. Thereafter, etching can be performed to implement the RWG waveguide as in step S150.

Polyimide is formed and a p-electrode and an n-electrode are formed (step S160).

The polyimide 26 may be laminated on one side of the RWG waveguide in the active region, and then the SiNx (27) thin film may be formed on the polyimide 26. A p-electrode 28 may be formed on the top of the ohmic layer 25. In addition, an n-electrode 29 may be formed on the top of the n-InP buffer layer 12 located next to the RWG.

An SLD having an operating speed of 10 Gbps or more can be manufactured through the processes of steps S110 to S160.

The above steps will be briefly described. The SLD of the tunable laser comprises growing a first epilayer on top of a SI (semi-insulating) substrate, regrowing the butt based on the first epilayer and forming a tapered SSC size converter, forming an optical waveguide and an RWG waveguide in the active region based on the first epilayer and in the SSC region based on the tapered SSC, forming a p-type electrode and n - < / RTI >

In the above step, the first epi layer may be formed by sequentially laminating an n-InP buffer layer, an InGaAsP passive waveguide layer, an n-InP lower cladding layer, a multiple quantum well active layer, and a p-InP upper cladding layer. The step of regrowing the butt and forming a tapered SSC (spot size converter) based on the first epi layer may include depositing a SiNx thin film on top of the p-InP upper cladding layer and depositing a SiNx thin film, a p-InP upper cladding layer, Etching the well active layer, growing an InGaAsP waveguide layer and a p-InP layer in the etched region, and partially etching the InGaAsP waveguide layer and the p-InP layer to form a tapered SSC at the top of the p-InP layer . &Lt; / RTI > In addition, the step of forming the optical waveguide and the RWG waveguide based on the first epi layer and the SSC may include forming the SiNx thin film, the p-InP upper cladding layer, the active region in which the multiple quantum well active layer is not etched, , Forming an optical waveguide by etching until before the n-InP buffer layer, and laminating a current blocking layer, a cladding layer and an ohmic layer on the top of the optical waveguide, and forming the RWG (rigid waveguide) waveguide.

Hereinafter, in FIGS. 3 to 5, the SLD produced based on the method disclosed in FIGS. 1 and 2 will be specifically described.

3 is a conceptual diagram illustrating an SLD according to an embodiment of the present invention.

Referring to FIG. 3, the SLD according to the embodiment of the present invention may use a semi-insulating (SI) substrate 11 as a substrate. Also, the active region and the SSC region of the SLD can be implemented in a planar buried heterostructure (PBH) structure. The active region may indicate the region in which the multiple quantum well active layer is present. The SSC area can indicate the realization area of the SSC by integrating it. SSC can be realized by growing an InGaAsP waveguide layer and a p-InP layer as described above. The active region and the SSC region can realize an optical waveguide. The optical waveguide located in the active region is referred to as an active region optical waveguide, and the optical waveguide located in the SSC region is referred to as an SSC region optical waveguide.

After the current blocking layers 22 and 23 are laminated on the left and right sides of the optical waveguide, the cladding layer 24 and the ohmic layer 25 are laminated on the upper side, an RWG waveguide including the active region and the SSC region is formed with a width of about 10 μm .

The RWG waveguide can be implemented by etching portions except the region used as the optical waveguide to reduce the parasitic capacitance. In addition, a polyimide 26 may be formed on one side of the RWG waveguide to form an electrode, and a SiNx layer 27 and a p-electrode 28 may be formed on the upper layer of the polyimide. In addition, an n-electrode 29 may be formed on the top of the etched n-InP buffer layer 12 to produce an optical waveguide. In addition, the RWG waveguide in the SSC region can be implemented with a structure that is bent at 7 to 15 degrees to reduce reflections at the outgoing interface.

4 is a conceptual view showing a cross-sectional view of an active region of an SLD according to an embodiment of the present invention.

Referring to FIG. 4, the active region may be implemented with a PBH structure as described above. In addition, in order to reduce the parasitic capacitance, the active region can be etched except for the active region optical waveguide of constant width including the multiple quantum well active layer 15. [ Etching for the active region optical waveguide can be performed up to the n-InP buffer layer 12.

An active region optical waveguide is formed by performing etching to form an RWG waveguide by stacking the current blocking layers 22 and 23, the cladding layer 24, and the ohmic layer 25. It is possible to etch the RWG waveguide so that the RWG waveguide is formed at a constant width at the upper end of the active region optical waveguide.

The N-electrode 29 may be formed at the top of the etched buffer layer 12 to form the optical waveguide and the p-electrode 28 may be formed at the top of the ohmic layer 25. In addition, the polyimide 26 may be laminated on one side of the RWG waveguide and the SiNx (27) thin film may be formed on the upper layer of the polyimide 26.

5 is a conceptual view showing a cross section of an SSC region according to an embodiment of the present invention.

Referring to FIG. 5, the SSC region may be implemented with a PBH structure like the active layer region. The SSC region can be implemented by etching except for the optical waveguide. As described above, in the SSC region, the InGaAsP waveguide layer 18 and the p-InP layer 19 are formed at the top of the etched region after etching the p-InP layer 16 and the multiple quantum well active layer 15, ) And then forming SSC on the top. The region excluding the region where the SSC is formed can be etched to the n-InP buffer layer 12. [

After the formation of the SSC region optical waveguide, the current blocking layers 22 and 23 are formed, and then the clad layer 24 and the ohmic layer 25 are sequentially laminated to form an RWG waveguide. It is possible to etch the RWC waveguide so that the RWG waveguide is formed at a predetermined width at the upper end of the SSC region optical waveguide. In the SSC region, polyimide may not be laminated.

6 is a conceptual diagram illustrating an SLD to which a phase control area according to an embodiment of the present invention is added.

In FIG. 6, a method for dividing the SLD into two regions and using one region as a region for phase control for variable refractive index is disclosed.

Referring to FIG. 6, the SLD realizes a P-type electrode 30 in the phase control region, which is an additional electrode in the SSC region, to adjust the refractive index of the optical signal by the current injected into the P- Can be implemented. That is, the SSC region of the SLD can be used as a phase control region. The phase control region may be located in the polymer waveguide region 51 of the external resonance laser to be described later. However, when the phase control area is placed in the SLD, the wavelength adjustment can be performed more easily. Specifically, the waveguide refractive index of the SLD has a value of about 3.2, and the waveguide refractive index of the SLD is more than twice as high as the refractive index of the polymer waveguide of 1.3. Therefore, when the phase control region is located in the SSC region, even when a small amount of current is input, the change of the refractive index can be largely changed, and the wavelength can be easily adjusted.

When the structure of the active layer of the SLD 61 is changed, a reflection type optical amplifier (optical network unit) which is an ONU (optical network unit) light source of a re-modulation system of a WDM (wavelength division multiplexing) reflective semiconductor optical amplifier (R-SOA).

The SLD according to the embodiment of the present invention may be implemented as an SLD structure in which buried deep ridge SSCs are integrated. In addition, a structure in which a passive waveguide core is formed under the active layer and waveguide, a structure in which a passive waveguide core is formed in a size of 2 to 9 μm below the SSC, a structure in which polyimide and benzocyclobutene Benzocyclobutene, BCB) may be formed on the outer periphery of the RWG.

7 is a conceptual diagram illustrating an external resonant laser based on an SLD according to an embodiment of the present invention.

Referring to FIG. 7, the SLD portion 61 and the polymer element portion 71 may be integrated to realize the external resonant laser 100.

The SLD portion 61 may include a highly reflective coating surface 31, an anti-reflective coating surface 32, and a thermoelectric cooler (TEC) 33 in the SLD region.

The polymer element portion 71 includes an RWG structure 51 of the active layer, a polymer grating region 52, an electrode 53 of a polymer grating region, an anti-reflection coating layer 54, a thermoelectric cooler (TEC) 55 of a polymer grating region, An optical fiber fixing block 56, and an optical fiber 57.

The rear interface of the SLD portion 61 as the light source can be realized by the highly reflective coated surface 51 and the front interface can be realized by the non-reflective coated surface 52. When an electric current is injected into the SLD portion 61, an optical signal can be generated in the active region. The optical signal generated in the active region can be injected into the waveguide 51 of the polymer element portion 71 through the front surface coated with anti-reflection after high reflection occurs at the rear interface of the active layer region. The optical signal injected into the waveguide 51 of the polymer device can be transmitted to a Bragg grating 52 formed in the polymer waveguide 51. [ The optical signal corresponding to the wavelength corresponding to the reflection period of the Bragg grating 52 among the optical signals transmitted to the Bragg grating 52 can be returned to the active area of the SLD 61. [

The oscillation can be performed when the optical signal becomes equal to or higher than a predetermined gain due to the resonance phenomenon between the high reflection film of the SLD and the Bragg grating 52. [ Transmission and reception of the optical signal between the active region and the Bragg grating 52 are repeated and oscillation can be performed when the optical signal becomes equal to or higher than a predetermined gain. The oscillated optical signal can be transmitted through the optical fiber 57. That is, an outer resonant laser can be realized by forming a resonator at a boundary of the highly reflective coating of the SLD portion 51 and a certain portion of the Bragg grating 52 formed in the polymer waveguide.

A thermoelectric cooler (TEC) 33 may be implemented in the SLD unit 61 for stabilizing the temperature of the optical signal of the oscillated wavelength. The polymer element portion 71 may be attached onto the silica submount. The output portion of the SLD portion 61 may be formed by tilting about 7 to 15 degrees in order to reduce reflection with respect to the polymer element portion 71. [ The polymer element can also be formed by tilting about 25 to 45 degrees corresponding to the tilt of the output portion of the SLD portion 61. [

The effective refractive index of the waveguide 51 of the polymer element portion 71 is 1.39 and the difference in effective refractive index can be 0.019. The thermo-optic coefficient of the polymer is 2.636 × 10 ^-4 / ° C. The characteristic of the polymer material is characterized by a large variable refractive index as compared with the injection power because the thermo-optic coefficient is larger than other materials. Therefore, when the polymer waveguide 51 is formed by braggating, the change of the reflection peak is large, so that the wavelength can be varied. The thermoelectric cooler 55 can be attached for accurate temperature control of the portion of the polymer element portion 71. Also, the non-reflective coating layer 54 may be formed at the end of the polymer element portion 71 to reduce light loss to the outside of the polymer.

8 is a conceptual diagram illustrating an external resonant laser based on an SLD according to an embodiment of the present invention.

In FIG. 8, the SLD to which the phase control region 30 is added and the integrated external resonant laser 100 are posted. It is possible to control the wavelength more precisely when the phase control region 30 is added.

It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined in the appended claims. It will be possible.

11. Semi-insulating substrate 12. n-InP buffer layer
13. Passive waveguide layer 14. Cladding layer under n-InP
15. Active layer 16. p-InP upper cladding layer
17. SiNx thin film 18. Butt coupling layer
19. p-InP cladding layer 20. SSC layer
21. Optical waveguide layer 22. p-InP current blocking layer
23. n-InP current blocking layer 24. p-InP cladding layer
25. p + -InGaAs ohmic layer 26. Polyimide layer
27. SiNx layer 28. P-type electrode
29. n-type electrode 30. P-type electrode in the phase control region
31. Highly reflective coated surface 32. Non-reflective coated surface
33. Thermoelectric cooler (TEC) of the SLD region 51. Polymer waveguide layer
52. Region of polymer grating 53. Electrode of polymer grating region
54. Anti-reflective coating layer
55. Thermoelectric cooler (TEC) in the polymer grating region.
56. Optical fiber fixing block 57. Optical fiber
61. SLD element 71. Polymer grating element region
100. External resonant laser portion

Claims

A method for implementing a superluminescent diode (SLD), which is a light source of a tunable laser,
Growing a first epitaxial layer on top of a semi-insulating substrate;
Regrowing the butt based on the first epilayer;
Forming a tapered spot size converter (SSC) on the re-grown butt layer;
Forming an optical waveguide in an active region based on the first epi-layer and in an SSC region based on the tapered SSC;
Forming an RWG waveguide on the optical waveguide; And
forming a p-type electrode and an n-type electrode.

The method according to claim 1,
The first epitaxial layer is formed by sequentially laminating an n-InP buffer layer, an InGaAsP passive waveguide layer, an n-InP lower clad layer, a multiple quantum well active layer, and a p-
SLD implementation method.

3. The method of claim 2,
Wherein regrowing the butt based on the first epilayer comprises:
Depositing a SiNx thin film on top of the p-InP upper cladding layer;
Etching the SiNx thin film, the p-InP upper clad layer, and the multiple quantum well active layer;
Forming an InGaAsP waveguide layer in the etched region; And
And forming a p-InP layer on the InGaAsP waveguide layer.
SLD implementation method.

The method of claim 3,
The step of forming the tapered SSC in the regrown butt layer comprises:
Partially etching the InGaAsP waveguide layer and the p-InP layer; And
And forming the tapered SSC on top of the p-InP layer.
SLD implementation method.

5. The method of claim 4,
Forming an optical waveguide based on the first epi-layer and the SSC,
Etching the unetched SiNx thin film, the p-InP upper cladding layer, the active region including the multiple quantum well active layer, and the SSC region partially before the n-InP buffer layer. ,
How to implement SDL.

6. The method of claim 5,
The step of forming the RWG waveguide on the optical waveguide includes:
Stacking a current blocking layer on the left and right sides of the optical waveguide;
Stacking a clad layer on the optical waveguide and the current blocking layer;
Stacking an ohmic layer on top of the clad layer; And
And selectively etching the current blocking layer, the cladding layer, and the ohmic layer.
SLD implementation method.

The method according to claim 6,
Wherein the active region and the SSC region are implemented in a PBH (planar buried heterostructure) structure.
SLD implementation method.

8. The method of claim 7,
Wherein the SSC region is implemented to bend 5 to 15 degrees.
SLD implementation method.

The method according to claim 1,
Wherein the RWG waveguide is implemented to have a width of 9 to 11 [micro] m.
SLD implementation method.

The method according to claim 1,
Further comprising implementing a p-type electrode of a phase control region that is an additional electrode in the SSC region to control the refractive index of the optical signal.
SLD implementation method.

As a superluminescent diode (SLD) which is a light source of a tunable laser,
A first epi layer formed on the top of a semi-insulating substrate;
A butt layer grown on at least a portion of the first epi layer;
A tapered SSC (spot size converter) formed on the butt layer;
An optical waveguide formed on the active region based on the first epi-layer and on the SSC region based on the tapered SSC;
An RWG waveguide formed on the optical waveguide;
A p-type electrode formed on the upper portion of the RWG waveguide; And
And an n-type electrode formed on a side portion of the RWG waveguide region.

12. The method of claim 11,
Wherein the first epitaxial layer includes an n-InP buffer layer, an InGaAsP passive waveguide layer, an n-InP lower cladding layer, a multiple quantum well active layer, and a p-InP upper cladding layer sequentially stacked from the top of the SI substrate , SLD.

13. The method of claim 12,
The butt layer is formed on the p-InP upper clad layer and the region where the multiple quantum well active layer is etched,
In the butt layer,
An InGaAsP waveguide layer formed on the n-InP lower cladding layer of the etched region; And
And a p-InP layer formed on the InGaAsP waveguide layer.

13. The semiconductor device according to claim 12, wherein the RWG waveguide includes:
A current blocking layer formed on the left and right sides of the optical waveguide;
A clad layer formed on the optical waveguide and the current blocking layer; And
And an ohmic layer formed on the clad layer.

The SLD according to claim 11, wherein the RWG waveguide has a width of 9 to 11 탆.

12. The method of claim 11,
Further comprising a p-type electrode in the phase control region on the SSC region, which is an additional electrode for adjusting the refractive index of the optical signal.