A semiconductor optical amplifier

Abstract

The application relates to the technical field of optical communication, and discloses a semiconductor optical amplifier which comprises a substrate (1), a bex layer (2), a substrate (1) which is provided with a bex layer (2) for regulating and controlling an optical field limiting factor, an excess layer (3), an excess layer (3) which is composed of an excess material and is arranged on the bex layer (2), a quantum well layer (4), a quantum well layer (4) which is composed of a quaternary compound material and is arranged on the transition layer, and a ridge waveguide layer (5), the ridge waveguide layer (5) being arranged on the quantum well layer (4). The semiconductor optical amplifier designed in the application has the advantages that the structure thereof actively controls light through the bex layer, buffers defects through the transition layer, and optimizes the integrated structure through the ridge waveguide layer, so that the semiconductor optical amplifier with low loss, high power conversion efficiency and easy integration is realized, and the amplification gain is improved.

Description

Technical Field

[0001] This invention relates to the field of optical communication technology, and in particular to a semiconductor optical amplifier. Background Technology

[0002] A semiconductor optical amplifier (SOA) is an electrically driven optical amplifier that directly amplifies the input optical signal.

[0003] The core structure of an optical fiber amplifier (SOA) is very similar to the active region of a laser, typically a PN junction or a similar multilayer semiconductor structure. When current is injected into the device, carrier inversion occurs in the active region. If an optical signal enters at this time, it gains gain through stimulated emission, thus achieving amplification. Compared to commonly used erbium-doped fiber amplifiers, SOAs have advantages such as small size, high integrability, multi-wavelength amplification, convenient driving, fast response speed, and multi-functional processing capabilities. They are suitable for integration with lasers, modulators, detectors, and silicon photonic chips. Currently, SOAs are used in power compensation, optical switching / gating, wavelength conversion, and all-optical signal processing in optical communication links.

[0004] Traditional optical amplifiers mainly use erbium-doped fiber amplifiers (EDFAs), such as the existing technology CN202210760397.9, which uses Er³⁺ (trivalent erbium ions) in erbium-doped fiber as the gain medium. Under the action of pump light, population inversion is formed, thereby amplifying the signal light in the communication band.

[0005] A typical EDFA usually includes the following components: Erbium-doped fiber (EDF): the medium that actually generates gain; a pump laser: providing energy; a WDM coupler: combining the pump light and signal light into the same fiber; an isolator: preventing reflected light from affecting the amplifier's stability; and a filter: suppressing ASE noise or shaping the gain spectrum. Due to the large number of components, EDFAs are relatively large and not easy to integrate. The stimulated emission spectrum of erbium ions covers the wavelength range of 1530-1625 nm, therefore EDFAs can only amplify light within this wavelength range.

[0006] SOA (Optically Oriented Amplifier) ​​is an important class of active optical devices, with its background technology originating from semiconductor lasers. With the development of high-speed optical communication, silicon photonics integration, and on-chip optical interconnects, modulator insertion loss, coupling loss, and waveguide transmission loss in these systems have become increasingly significant. This necessitates a small, electrically driven, and easily integrated optical amplifier, leading to the widespread application of SOA. SOA implementation methods are primarily based on semiconductor active gain structures. The core of this approach is to construct gain waveguides on III-V group semiconductor materials, commonly including InP, InGaAsP, and AlGaInAs, which can cover the 1.3 μm or 1.55 μm communication bands. Internally, devices typically employ double heterojunctions, separated confined heterojunctions (SCH), or multiple quantum wells (MQW) structures to enhance carrier and optical field confinement, thereby achieving higher gain and lower drive current.

[0007] In its implementation, the active region, cladding, and waveguide structure must first be designed to allow the input light to propagate along the waveguide and fully couple with the gain region. Then, current is injected through electrodes to establish carrier inversion within the active region. When an external optical signal enters, stimulated emission is triggered, amplifying the input light. To prevent the device from resonating due to end-face reflection like a laser, SOA typically employs anti-reflection coatings, tilted waveguides, or low-reflection end-face designs to suppress feedback. Therefore, it is essentially a semiconductor optical device that "has gain but does not resonate."

[0008] From a device form perspective, common SOA implementations include traveling-wave SOA, Fabry-Perot SOA, and reflective RSOA. Traveling-wave SOA is most commonly used for communication amplification and on-chip gain compensation; RSOA is often used in access networks and reflective modulation systems. For silicon photonics platforms, heterogeneous integration or hybrid integration methods can also be used to bond III-V gain materials to silicon waveguides to achieve on-chip amplification.

[0009] Because SOA (Optical Array of Assemblers) are small, have high heat dissipation requirements, and are typically integrated into the system, they are more sensitive to power consumption. Currently, most SOA systems have low Power Conversion Efficiency (PCE), with only ~20% of electrical power being converted into optical power. The remaining electrical power is dissipated as heat, resulting in higher system power consumption and increased SOA temperature, further reducing PCE. Summary of the Invention

[0010] This invention addresses the problem of low power conversion efficiency in existing technologies, where only 20% of electrical power is converted into optical power and the remaining electrical power is consumed as heat. This not only results in high system power consumption but also causes the SOA temperature to rise, further reducing the power conversion efficiency. The invention provides a semiconductor optical amplifier.

[0011] To solve the above-mentioned technical problems, the present invention provides the following technical solution: A semiconductor optical amplifier comprising: Base, A BEX layer is provided on the substrate to control the light field confinement factor. A transition layer, consisting of a transition material, is provided on the bex layer; A quantum well layer, with a quantum well layer composed of a quaternary compound material on the transition layer; Ridge waveguide layer: A ridge waveguide layer is provided on the quantum well layer.

[0012] The structure achieves a semiconductor optical amplifier with high power conversion efficiency and easy integration by using a bex layer for active light control, a transition layer for buffering, and a ridge waveguide layer for optimized integration, and also improves its amplification gain.

[0013] Preferably, the ridge waveguide layer includes a waveguide input end and a waveguide output end, with an optical prevention area and an optical amplification area provided between the waveguide input end and the waveguide output end.

[0014] Preferably, the thickness of the light prevention region is greater than the thickness of the light amplification region.

[0015] Preferably, the ridge width of the light prevention area is smaller than the ridge width of the light amplification area.

[0016] Preferably, the ridge width of the light prevention region and the ridge width thickness of the light amplification region are 1.5-5 μm.

[0017] Preferably, the BEX layer corresponding to the light prevention region is etched, while the BEX layer corresponding to the light amplification region is not etched.

[0018] Preferably, the substrate material is InP.

[0019] Preferably, the refractive index of the BEX layer material is greater than that of the quantum well layer material. This invention, by adopting the above technical solutions, has significant technical effects: The semiconductor optical amplifier designed in this invention achieves low loss, high power conversion efficiency, and easy integration through active light control in the bex layer, defect buffering in the transition layer, and optimized integration structure in the ridge waveguide layer, while also improving amplification gain.

[0020] This invention improves the amplification gain of a semiconductor optical amplifier by adjusting the waveguide ridge width to change the optical field confinement factor and current distribution.

[0021] This invention improves the amplification gain of a semiconductor optical amplifier by adjusting the light field confinement factor of the bex layer. Attached Figure Description

[0022] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings: Figure 1 This is a cross-sectional view of the SOA of the present invention.

[0023] Figure 2 This is a top view of the SOA of this invention.

[0024] Figure 3 This is the SOA optical mode field diagram of the present invention.

[0025] Figure 4 This is a schematic diagram of the ridge waveguide layer structure of the present invention.

[0026] Figure 5 This is a simulation diagram of the present invention without a bex structure.

[0027] Figure 6 This is a simulation diagram of the bex structure of the present invention.

[0028] Figure 7 This is a graph showing the measured data of the SOA chip of this invention.

[0029] Figure 8 This is a graph showing the measured data of the SOA chip of this invention.

[0030] Among them, 1—substrate, 2—Bex layer, 3—transition layer, 4—quantum well layer, 5—ridge waveguide layer, 51—Waveguide input end, 52—Waveguide output end, 53—Optical prevention area, 54—Optical amplification area; SOA (Semiconductor Optical Amplifier); Bex (Beam expender layer) is a beam expansion layer. EDFA (Erbium-Doped Fiber Amplifier); MQW (Multiple Quantum Well) quantum well; OCF (Optical Confinement Factor) is the optical field confinement factor. PCE (Power Conversion Efficiency) refers to the power conversion efficiency. Detailed Implementation

[0031] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments.

[0032] Example 1 A semiconductor optical amplifier, comprising Base 1, Bex layer 2, a layer for adjusting the optical field confinement factor is provided on the substrate 1. Transition layer 3, a transition layer 3 composed of transition material is provided on the bex layer 2; Quantum well layer 4, the transition layer is provided with a quantum well layer 4 composed of quaternary compound material; Ridge waveguide layer 5 is located on top of quantum well layer 4. The substrate 1 is made of InP. The conversion of electric current into light primarily occurs at the quantum well layer 4 (MQW). The refractive index of bex layer 2 is greater than that of quantum well layer 4.

[0033] The material composition of the transition layer is InP.

[0034] Example 2 A semiconductor optical amplifier, comprising Base 1, Bex layer 2, a layer for adjusting the optical field confinement factor is provided on the substrate 1. Transition layer 3, a transition layer 3 composed of transition material is provided on the bex layer 2; Quantum well layer 4, the transition layer is provided with a quantum well layer 4 composed of quaternary compound material; Ridge waveguide layer 5 is provided on the quantum well layer 4. The substrate 1 is made of InP.

[0035] The refractive index of bex layer 2 is greater than that of quantum well layer 4.

[0036] exist Figure 2 In the structure, one end is the optical input port, the middle is the gain waveguide layer, and the other end is the optical output port. The gain waveguide layer has a structural width W1 and... Figure 1 The W1 is completely identical. When light with lower power enters from the optical input port, it is gradually amplified during its propagation along the waveguide direction and is finally output from the optical output port.

[0037] The ridge waveguide layer 5 includes a waveguide input end 51 and a waveguide output end 52, and an optical prevention area 53 and an optical amplification area 54 are provided between the waveguide input end 51 and the waveguide output end 52.

[0038] The thickness of the light prevention region 53 is greater than the thickness of the light amplification region 54.

[0039] The ridge width of the light prevention zone 53 is smaller than that of the light amplification zone 54.

[0040] The ridge width of the light prevention region 53 is 1.5 μm and the ridge width and thickness of the light amplification region 54 are 5 μm.

[0041] Example 3 A semiconductor optical amplifier, comprising Base 1, Bex layer 2, a layer for adjusting the optical field confinement factor is provided on the substrate 1. Transition layer 3, a transition layer 3 composed of transition material is provided on the bex layer 2; Quantum well layer 4, the transition layer is provided with a quantum well layer 4 composed of quaternary compound material; Ridge waveguide layer 5 is provided on the quantum well layer 4. The substrate 1 is made of InP.

[0042] The refractive index of bex layer 2 is greater than that of quantum well layer 4.

[0043] The ridge waveguide layer 5 includes a waveguide input end 51 and a waveguide output end 52, and an optical prevention area 53 and an optical amplification area 54 are provided between the waveguide input end 51 and the waveguide output end 52.

[0044] The thickness of the light prevention region 53 is greater than the thickness of the light amplification region 54.

[0045] The ridge width of the light prevention zone 53 is smaller than that of the light amplification zone 54.

[0046] The ridge width of the light prevention region 53 is 2µm and the ridge width and thickness of the light amplification region 54 are 5µm.

[0047] Example 4 A semiconductor optical amplifier, comprising Base 1, Bex layer 2, a layer for adjusting the optical field confinement factor is provided on the substrate 1. Transition layer 3, a transition layer 3 composed of transition material is provided on the bex layer 2; Quantum well layer 4, the transition layer is provided with a quantum well layer 4 composed of quaternary compound material; Ridge waveguide layer 5 is provided on the quantum well layer 4. The substrate 1 is made of InP.

[0048] The ridge waveguide layer 5 includes a waveguide input end 51 and a waveguide output end 52, and an optical prevention area 53 and an optical amplification area 54 are provided between the waveguide input end 51 and the waveguide output end 52.

[0049] The thickness of the light prevention region 53 is greater than the thickness of the light amplification region 54.

[0050] The ridge width of the light prevention zone 53 is smaller than that of the light amplification zone 54.

[0051] The ridge width of the light prevention region 53 is 2µm and the ridge width and thickness of the light amplification region 54 are 5µm.

[0052] The BEX layer 2 corresponding to the light prevention region 53 is etched, while the BEX layer 2 corresponding to the light amplification region 54 is not etched. The refractive index of the BEX layer 2 material is greater than that of the quantum well layer 4 material.

[0053] Example 5 Based on the above embodiments, this embodiment Figure 3 This is an optical mode field diagram of an SOA (Optical Mode Architecture), showing the quantum well layer. The colored areas represent the optical mode field. Although light propagates within the waveguide, the optical field doesn't remain confined to the active layer; it typically extends upwards and downwards into the cladding, waveguide layer, and even adjacent materials. The optical confinement factor (OCF) represents the proportion of the total energy of the optical mode that is actually distributed within the quantum well layer. A large OCF means greater overlap between the optical mode and the quantum well layer, enabling rapid light amplification. However, this can lead to lower efficiency and weaker amplification in the latter half of the chip. Therefore, designs with a large OCF tend to have smaller chip sizes and are not suitable for high-gain chips. The simulation diagram of the SOA OCF varying with ridge width W1 shows that as W1 widens, the OCF also increases.

[0054] waveguide structure such as Figure 4 As shown. The waveguide input facilitates coupling with the seed light from the front end, and the moderate waveguide width improves optical coupling efficiency. The waveguide output couples with the rear structure, and the moderate waveguide width further enhances optical coupling efficiency. In the optical pre-amplification region, the waveguide width is narrow, and the resistance is high, resulting in less current flowing through this region. The narrow surface waveguide width leads to a smaller optical field confinement factor, resulting in higher optical amplification efficiency, but a lower absolute amplification value. After passing through the optical pre-amplification region, the pre-amplified light enters the optical amplification region. Here, the waveguide width is wide, the optical field confinement factor is large, and more current flows through the optical amplification region, completing the final amplification.

[0055] Figure 1 The refractive index of the medium-structured bex layer material is greater than that of the InP quaternary compound. The bex layer can pull down the optical field and reduce the optical field confinement factor.

[0056] Figure 5 and Figure 6 These are simulation images with and without the BEX structure, respectively. With the BEX structure, the overall optical field is lower, with less overlap with quantum well layer 4, resulting in a smaller optical field confinement factor. Without the BEX structure, the optical field center is located at quantum well layer 4, with more overlap, resulting in a larger optical field confinement factor.

[0057] Partial etching of the bex can also be used to modulate the optical field confinement factor. Figure 5The preservation of bex in the large-area prevention method can help reduce the light field confinement factor. Figure 5 The bex at the amplification region is etched away, which increases the optical field confinement factor. By changing the corresponding ridge width, the optical field confinement factor of the SOA can be significantly changed, thereby improving the output power and amplification gain.

[0058] Figure 7 and Figure 8 These are actual measured data for the SOA chip. With a 1A input current, the device voltage is 1.7V and the power consumption is 1.7W. At 25℃, the chip emits 440mW of light, and the PCE is 0.44W / 1.7W = 26%.

Claims

1. A semiconductor optical amplifier, characterized in that: include Base (1) The substrate (1) has a bex layer (2) for controlling the light field confinement factor. Transition layer (3): A transition layer (3) composed of transition material is provided on the bex layer (2); A quantum well layer (4) is provided on the transition layer, consisting of a quantum well layer (4) made of a quaternary compound material. The ridge waveguide layer (5) is provided on the quantum well layer (4).

2. A semiconductor optical amplifier according to claim 1, characterized in that: The ridge waveguide layer (5) includes a waveguide input end (51) and a waveguide output end (52). An optical prevention area (53) and an optical amplification area (54) are provided between the waveguide input end (51) and the waveguide output end (52).

3. A semiconductor optical amplifier according to claim 2, characterized in that: The thickness of the light prevention region (53) is greater than the thickness of the light amplification region (54).

4. A semiconductor optical amplifier according to claim 2, characterized in that: The ridge width of the light prevention zone (53) is smaller than that of the light amplification zone (54).

5. A semiconductor optical amplifier according to claim 2, characterized in that: The ridge width of the light prevention region (53) and the ridge width thickness of the light amplification region (54) are 1.5-5 μm.

6. A semiconductor optical amplifier according to claim 2, characterized in that: The bex layer (2) corresponding to the light prevention area (53) is etched, while the bex layer (2) corresponding to the light amplification area (54) is not etched.

7. A semiconductor optical amplifier according to claim 1, characterized in that: The substrate (1) is made of InP.

8. A semiconductor optical amplifier according to claim 1, characterized in that: The refractive index of the bex layer (2) is greater than that of the quantum well layer (4).

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