Semiconductor devices integrating branched waveguides and photodiodes

Abstract

This application relates to a semiconductor device integrating a branched waveguide and a photodiode, belonging to the field of semiconductor optoelectronics technology. The laser includes a semiconductor laser, a semiconductor optical amplifier, a branched waveguide, and a photodiode formed on the same semiconductor substrate. The light output from the semiconductor laser is transmitted to the semiconductor optical amplifier, where a Y-branch structure is formed. The main waveguide amplifies and outputs a portion of the light, while the branched waveguide receives the remaining light and transmits it to the photodiode. The photodiode performs photoelectric conversion on the received light, enabling monitoring of the forward optical power of the semiconductor laser. This structure achieves real-time monitoring of the laser's output optical power, improving the stability and reliability of the laser.

Description

Technical Field

[0001] This application relates to the field of semiconductor optoelectronics technology, specifically to a semiconductor device integrating a branched waveguide and a photodiode. Background Technology

[0002] Semiconductor lasers, as an important light source, are widely used in optical communication, optical storage, medical applications, and industrial processing. As these applications increasingly demand higher stability and reliability from light sources, accurate monitoring of the output optical power of semiconductor lasers has become crucial. Traditionally, external photodetectors are used to monitor the output optical power of semiconductor lasers, but this method not only increases the size and complexity of the system but also makes it difficult to achieve real-time and accurate monitoring of the laser's output optical power.

[0003] Currently, integrated semiconductor lasers have become a research hotspot. For example, Chinese patent application CN117254346A discloses a high-power chaotic semiconductor laser based on Y-waveguide coupling, comprising a first DFB laser, a second DFB laser, a Y-waveguide, a DBR grating, and a tapered waveguide optical amplifier. The lasing waves from the two DFB lasers are interference-coupled at the coupling point via the Y-waveguide, and then amplified by the tapered waveguide optical amplifier, outputting a broadband, high-power chaotic laser with indistinct time delay characteristics. While this structure achieves laser integration, it lacks the function of monitoring the output optical power.

[0004] Chinese patent application CN110048304B describes an integrated DFB semiconductor laser. This laser has a branched arc-shaped waveguide extending from half the cavity length towards the laser's output face. At the output face, the branched arc-shaped waveguide and the straight ridge waveguide have a gap, and an ion implantation region is formed between them. While this structure achieves integrated light output and detection, its branched waveguide structure is complex, its manufacturing process is difficult, and it is challenging to achieve high-precision optical power monitoring.

[0005] Chinese patent application CN103515841A discloses an optical semiconductor device that integrates a semiconductor laser section and an optical modulator section on an n~InP substrate. The semiconductor laser section has a vertical ridge, and the optical modulator section has an inverted mesa ridge. This structure, by changing the ridge shape, can stabilize the transverse mode of the oscillating light of the semiconductor laser section and prevent the degradation of frequency characteristics, but it does not solve the problem of monitoring the output light power of the laser.

[0006] Chinese patent application CN103956652A describes a low-cost tunable DFB semiconductor laser with an integrated modulator, in which multiple DFB semiconductor lasers share a single modulator, and the tunable wavelength range can be extended by increasing the number of lasers or through active / passive integration. While this structure reduces cost and improves practicality and ease of use, it also lacks an effective means of monitoring the laser's output optical power.

[0007] Existing semiconductor lasers generally suffer from the following problems: First, they lack real-time and accurate monitoring methods for output optical power, making it difficult to ensure stable operation of the laser in practical applications; second, they have low integration, requiring external photodetectors to monitor optical power, which increases the size and complexity of the system; and third, they have insufficient system stability and reliability, especially in high-power semiconductor laser applications, where fluctuations in output optical power may lead to a decrease in system performance or even damage. Summary of the Invention

[0008] To address the shortcomings of existing semiconductor laser technologies, such as the lack of real-time and accurate monitoring of output optical power, low integration, and insufficient system stability and reliability, this application provides a semiconductor device integrating a branched waveguide and a photodiode to achieve high-precision and high-linearity front optical power monitoring. This semiconductor device achieves high-linearity front optical power monitoring while functioning as a high-quality light source, thus meeting the stability and reliability requirements of various application scenarios.

[0009] The technical solution adopted by this application to solve its technical problem is: to provide a semiconductor device integrating a branch waveguide and a photodiode, including: a semiconductor laser, a semiconductor optical amplifier and a photodiode formed on the same semiconductor substrate;

[0010] The output light of the semiconductor laser is transmitted to a semiconductor optical amplifier, forming a Y-branch structure on the amplifier. The Y-branch structure includes a main waveguide and a branch waveguide. The main waveguide amplifies and outputs a portion of the light, while the branch waveguide receives another portion and transmits it to a photodiode. The photodiode performs photoelectric conversion on the received light, which is used to monitor the forward optical power of the semiconductor laser.

[0011] As a further improvement to this application, the semiconductor laser, semiconductor optical amplifier, branch waveguide and photodiode all adopt buried heterojunction waveguide or ridge waveguide structure.

[0012] As a further improvement to this application, the semiconductor laser is a distributed feedback laser, a distributed Bragg grating laser, or a Fabry-Perot laser.

[0013] As a further improvement of this application, the shape of the orthogonal projection of the semiconductor laser onto the semiconductor substrate includes at least a strip shape.

[0014] As a further improvement of this application, one end of the semiconductor laser is connected to a semiconductor optical amplifier; at the contact point between the semiconductor laser and the semiconductor optical amplifier, the widths of both are the same, and the bending angle of the semiconductor optical amplifier is in the range of 0° to 50°.

[0015] As a further improvement to this application, the shape of the orthogonal projection of the semiconductor optical amplifier onto the semiconductor substrate includes at least a strip shape, a cone shape, and an inverted cone shape.

[0016] As a further improvement of this application, the included angle between the branch waveguide and the semiconductor laser is in the range of 0° to 90°.

[0017] As a further improvement of this application, the position, angle, and width of the branch waveguide can be adjusted according to actual needs to obtain different beam splitting ratios, thereby adjusting the optical power entering the photodiode.

[0018] As a further improvement to this application, the shape of the orthogonal projection of the photodiode onto the semiconductor substrate includes at least a strip, a polygon, a circle, and an ellipse.

[0019] As a further improvement of this application, it also includes: an electrical isolation region; an electrical isolation region is provided between the semiconductor laser, the semiconductor optical amplifier and the photodiode, for independent current or voltage control of the three respectively.

[0020] The beneficial effects of this application are as follows: This semiconductor device integrating a branched waveguide and a photodiode monolithically integrates a photodiode, a semiconductor optical amplifier, and a semiconductor laser through branched waveguide coupling. While ensuring the integrity of the main laser optical path, it constructs an auxiliary monitoring optical path, enabling real-time and accurate monitoring of the laser's output optical power, providing reliable data support for closed-loop control. The photodiode monitors the front optical power of the semiconductor laser with high precision and high linearity. The high integration design helps enhance stability and reliability, making it suitable for applications such as optical interconnect modules, optical I / O chips, and co-packaged optics. Compared with existing technologies, this application achieves front optical monitoring functionality through a branched waveguide structure, solving the problem that traditional semiconductor lasers cannot accurately monitor output optical power in real time, while simultaneously improving integration and reliability. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the orthographic projection structure of the semiconductor device integrating a branched waveguide and a photodiode in an embodiment of this application on a semiconductor substrate.

[0022] Figure 2 The light field distribution of the semiconductor device integrating a branched waveguide and a photodiode at different locations in the cavity is shown in the embodiment of this application.

[0023] Figure 3 The splitting ratio of the Y-branch structure of the semiconductor device integrating branched waveguides and photodiodes in this application embodiment;

[0024] Figure 4 This represents the relationship between the waveguide angle θ and the ratio of the optical field intensity in the branch waveguide to the optical field intensity in the main waveguide.

[0025] Figure 5 This represents the relationship between the width of the branch waveguide and the ratio of the optical field intensity in the branch waveguide to the optical field intensity in the main waveguide.

[0026] Wherein: 101, semiconductor substrate; 102, semiconductor laser; 103, semiconductor optical amplifier; 104, branch waveguide; 105, photodiode; 106, main waveguide. Detailed Implementation

[0027] The technical solution of this application will now be clearly and completely described with reference to the accompanying drawings and embodiments. Obviously, the described embodiments are merely some embodiments of this application, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0028] Terminology Explanation:

[0029] DFB, Distributed Feedback;

[0030] DBR, Distributed Bragg Reflector;

[0031] FP, Fabry-Perot;

[0032] SOA, Safe Operating Area;

[0033] BH semiconductor laser, or Buried Heterostructure Semiconductor Laser, is a semiconductor laser that improves laser performance by using a special heterojunction design to efficiently confine the optical field and current.

[0034] A cleavage plane is a smooth surface formed when a crystalline material fractures along a specific crystal plane under the action of an external force. This phenomenon originates from the periodicity and anisotropy of the atomic arrangement within the crystal—the bonding forces between atoms on different crystal planes differ, and when the external force exceeds the withstand limit of the crystal plane with weaker bonding forces, the crystal will fracture along that crystal plane.

[0035] A waveguide structure is a structure that can confine and guide the propagation of electromagnetic waves (including light waves) in a specific direction. Its working principle is based on the phenomenon of total internal reflection of electromagnetic waves at the interface between different media—when an electromagnetic wave travels from an optically denser medium (higher refractive index) to an optically less dense medium (lower refractive index), and the angle of incidence is greater than the critical angle, total internal reflection will occur, thereby confining the electromagnetic wave to propagate within the core region of the waveguide.

[0036] Buried heterojunction waveguides are a special type of heterojunction waveguide structure in which the core layer (usually a material with optical gain) is completely buried in a cladding material with a low refractive index. This structure can more effectively confine the optical field, reduce light leakage, thereby reducing optical transmission loss and improving the luminous efficiency and modulation speed of the device.

[0037] Ridge waveguides, derived from planar waveguides, feature a raised "ridge" structure in a specific region of their core layer. The presence of the ridge disrupts the symmetry of the planar waveguide, concentrating the light field more around it and enhancing lateral confinement. Compared to ordinary planar waveguides, ridge waveguides offer better mode selectivity and lower bending loss, and are commonly used in integrated optical chips for optical connections, beam splitters, and beam combiners, such as optical switches and optical couplers.

[0038] A Bragg grating is an optical structure consisting of a dielectric layer or a refractive index modulation region with periodically varying refractive index. When light propagates in a Bragg grating, light of a specific wavelength that satisfies the Bragg condition (optical path difference is an integer multiple of the wavelength of light) will be strongly reflected, while light of other wavelengths can pass through with almost no loss.

[0039] A quantum well is an ultrathin layer structure formed by alternating growth of two different semiconductor materials. Its core is a narrow bandgap material with a thickness on the nanometer scale (typically 1-100 nm), surrounded by wide bandgap materials (potential barriers) on both sides, forming a potential energy distribution similar to a "well". Because the movement of electrons and holes in the direction perpendicular to the well layer is confined within the nanoscale, its energy exhibits quantized characteristics (similar to energy levels in an atom), hence the name "quantum well".

[0040] Quantum dots are semiconductor nanocrystals with three-dimensional dimensions in the nanometer range (typically 1-10 nm). Their electrons and holes are completely confined in all three spatial directions, exhibiting an atomic-like discrete energy level structure. Common materials include CdSe, InP, and PbS, which can be prepared through chemical synthesis or molecular beam epitaxy.

[0041] The following illustrative example illustrates a semiconductor device integrating a branched waveguide and a photodiode. It should be noted that this illustration is merely a specific embodiment of this application and does not limit the scope of protection of this application.

[0042] Figure 1 This is a schematic diagram of the orthographic projection structure of the semiconductor device integrating a branched waveguide and a photodiode in an embodiment of this application on a semiconductor substrate.

[0043] like Figure 1 As shown, the integrated semiconductor device comprising a branch waveguide and a photodiode includes: a semiconductor substrate 101, a semiconductor laser 102, a semiconductor optical amplifier 103, and a photodiode 105. The output light from the semiconductor laser 102 is transmitted to the semiconductor optical amplifier 103, forming a Y-branch structure on the amplifier. The Y-branch structure includes a main waveguide 106 and a branch waveguide 104. The main waveguide 106 amplifies and outputs a portion of the light, while the branch waveguide 104 receives the remaining light and transmits it to the photodiode 105. The photodiode 105 performs photoelectric conversion on the received light, thereby monitoring the forward optical power of the semiconductor laser 102.

[0044] It should be noted that the photodiode 105 is a semiconductor device that converts optical signals into electrical signals, belonging to the category of optical sensors. It operates based on the photoelectric effect; when light shines on its PN junction, electron-hole pairs are generated, forming a photocurrent, thus enabling the detection and measurement of the optical signal. Through the photoelectric effect of the semiconductor PN junction, light energy is converted into a measurable electrical signal, enabling the monitoring of the forward optical power of the semiconductor laser 102.

[0045] According to embodiments of this application, the waveguide angle θ between the branch waveguide 104 and the semiconductor laser 102 ranges from 0° to 90°. The waveguide angle θ directly affects the coupling efficiency between the branch waveguide 104 and the semiconductor laser 102. When θ = 0°, the waveguides of the branch waveguide 104 and the semiconductor laser 102 are perfectly parallel, resulting in optimal mode matching and the highest coupling efficiency. As θ increases, the propagation path of the beam between the waveguides of the branch waveguide 104 and the semiconductor laser 102 shifts, leading to increased mode mismatch and a gradual decrease in coupling efficiency. The range of 0° to 90° provides design flexibility. In applications requiring a compact layout, θ can be appropriately increased to save space. For example, using gradient mode coupling technology allows the beam to gradually adapt to angle changes, reducing mode mismatch loss. The waveguide angle θ also affects optical loss and optical reflection. When θ is small, optical loss is low, but optical reflection may increase. As θ increases, optical reflection may decrease, but mode mismatch loss increases. An appropriate waveguide angle θ helps reduce mode conversion loss and radiation loss. When θ is within a reasonable range, the beam propagation in the waveguide is more stable, reducing energy loss due to mode abrupt changes or radiation.

[0046] According to embodiments of this application, the semiconductor optical amplifier 103 has a certain bending angle φ, which ranges from 0° to 50°. The bending angle φ affects the bending waveguide loss in the semiconductor optical amplifier 103. When φ = 0°, the waveguide is straight, and the loss is lowest. As φ increases, the bending loss gradually increases, mainly due to radiation loss and mode mismatch loss. The range of 0° to 50° allows for a trade-off between bending loss and device integration. A smaller φ helps reduce bending loss but may limit device layout; a larger φ increases integration but requires optimization of the bending radius and waveguide structure to reduce bending loss. The performance requirements of the semiconductor optical amplifier 103 vary in different application scenarios. By adjusting the bending angle φ, specific optical signal processing (such as optical delay and optical switching) can be achieved to meet different application needs.

[0047] According to embodiments of this application, the semiconductor laser 102, semiconductor optical amplifier 103, branch waveguide 104, and photodiode 105 may employ buried heterojunction waveguide or ridge waveguide structures.

[0048] Buried heterojunction waveguides are waveguide structures that achieve dual confinement of the optical field and charge carriers through heterostructures (composed of semiconductor materials with different band gaps). Their core feature is embedding the active region (such as a quantum well or quantum dot) within a low-refractive-index, wide-bandgap cladding layer to form a "channel-like" optical waveguide. Common types include: channel semiconductor substrate buried heterojunctions, dual-channel planar buried heterojunctions, and etched mesa buried heterojunctions.

[0049] Among them, the ridge waveguide structure is a waveguide structure formed by etching to create ridge-like protrusions. It can be divided into single-ridge waveguides (T-shaped) and double-ridge waveguides (H-shaped). Its core feature is that the electromagnetic field distribution is controlled by the ridge structure, and single-mode operation is achieved through mode modulation.

[0050] According to embodiments of this application, the semiconductor laser 102 may be a distributed feedback laser, a distributed Bragg grating laser, or a Fabry-Perot laser.

[0051] Distributed feedback lasers achieve optical feedback by fabricating periodic gratings near the interface of the active waveguide region and utilizing the periodic change in the refractive index of the waveguide. Their core structure involves directly embedding a Bragg grating within the resonant cavity, covering the entire active region to form a "distributed feedback" mechanism. Typical examples are indium phosphide (InP)-based or gallium arsenide (GaAs)-based semiconductors.

[0052] Distributed Bragg reflector lasers integrate Bragg gratings as mirrors at both ends of the active region. The grating region is used only for wavelength selection, and there is no grating in the gain region. The typical structure is a three-section design: active region, Bragg reflector region, and phase control region.

[0053] The Fabry-Perot laser utilizes a semiconductor cleavage surface to form an FP resonant cavity, with cleavage surface mirrors at both ends and a strip-shaped active region. Its structure is simple and can be realized with a single epitaxial growth step.

[0054] According to embodiments of this application, the shape of the orthographic projection of the semiconductor laser 102 onto the semiconductor substrate 101 includes, but is not limited to, a strip shape; the shape may also be other continuous lines.

[0055] According to an embodiment of this application, a semiconductor optical amplifier 103 is integrated at one end of the semiconductor laser 102. At the contact point between the semiconductor laser 102 and the semiconductor optical amplifier 103, the widths of the two are the same. This design can ensure the effective propagation of light.

[0056] According to embodiments of this application, the orthographic projection shape of the photodiode 105 on the semiconductor substrate 101 includes, but is not limited to, strip, polygon, circle, and ellipse.

[0057] According to an embodiment of this application, an electrical isolation region is provided between the semiconductor laser 102, the semiconductor optical amplifier 103, and the photodiode 105, so that the current or voltage of each of the three can be controlled independently.

[0058] In the above scheme, the semiconductor laser 102, as the light source, is directly affected by the current and voltage. Electrical connections with other devices may lead to current leakage, thus affecting the output power and wavelength stability of the semiconductor laser 102. The semiconductor optical amplifier 103 amplifies the optical signal, and its performance parameters, such as gain and noise figure, are also precisely controlled by the operating current and voltage. The presence of the electrical isolation region ensures that the optical amplifier can independently adjust its operating state to achieve optimal optical signal amplification. The photodiode 105, as the optical signal receiver, has performance parameters such as response speed and sensitivity that are crucial to the overall system performance. The electrical isolation region prevents the photodiode 105 from being affected by electrical noise from other devices, thus ensuring its accurate detection of optical signals.

[0059] Furthermore, the electrically isolated region reduces current leakage, enabling the semiconductor laser 102 to operate under more stable current and voltage, thereby improving output power and wavelength stability. By independently controlling the operating current and voltage of the semiconductor optical amplifier 103, the electrically isolated region facilitates more precise gain control and a lower noise figure, improving the quality of optical signal amplification. The electrically isolated region reduces interference from electrical noise, allowing the photodiode 105 to respond more quickly to changes in the optical signal and improving its sensitivity in detecting optical signals.

[0060] The technical solution of this application will be described in detail below through specific embodiments.

[0061] Example 1

[0062] like Figure 1 As shown, this embodiment provides a semiconductor device integrating a branched waveguide and a photodiode, including a semiconductor laser 102, a semiconductor optical amplifier 103, and a photodiode 105, all formed on the same semiconductor substrate 101.

[0063] The structure of the semiconductor device integrating the branch waveguide and photodiode is as follows: The output light of the semiconductor laser 102 is transmitted to the semiconductor optical amplifier 103, forming a Y-branch structure on the semiconductor optical amplifier 103. The Y-branch structure includes a main waveguide 106 and a branch waveguide 104. The main waveguide 106 amplifies and outputs part of the light, while the branch waveguide 104 receives another part of the light and transmits it to the photodiode 105. The photodiode 105 performs photoelectric conversion on the received light, thereby monitoring the forward optical power of the semiconductor laser 102.

[0064] The semiconductor laser 102, semiconductor optical amplifier 103, branch waveguide 104, and photodiode 105 employ a buried heterojunction waveguide structure. The semiconductor laser 102 uses a distributed feedback laser structure. The orthographic projection of the semiconductor laser 102 onto the semiconductor substrate is strip-shaped. One end of the semiconductor laser 102 is connected to the semiconductor optical amplifier 103. At the contact point between the semiconductor laser 102 and the semiconductor optical amplifier 103, their widths are the same, and the bending angle of the semiconductor optical amplifier 103 is 30°. The orthographic projection of the semiconductor optical amplifier 103 onto the semiconductor substrate is also strip-shaped. A branch waveguide 104 is formed on one side of the semiconductor optical amplifier 103. The branch waveguide 104 and the main waveguide 106 constitute a Y-branch structure, and the waveguide angle between the branch waveguide 104 and the semiconductor laser 102 is 45°. The position, angle, and width of the branch waveguide 104 can be adjusted according to actual needs to achieve different splitting ratios, thereby adjusting the optical power entering the photodiode 105. The orthographic projection of photodiode 105 onto the semiconductor substrate is strip-shaped.

[0065] The semiconductor device integrating the branch waveguide and photodiode also includes an electrically isolated region. An electrically isolated region is provided between the semiconductor laser 102, the semiconductor optical amplifier 103 and the photodiode 105, so that the three can be independently controlled by current or voltage.

[0066] The working principle of this semiconductor device integrating a branch waveguide and a photodiode is as follows: The semiconductor laser 102 generates laser light under injected current, and the output laser light enters the semiconductor optical amplifier 103. In the semiconductor optical amplifier 103, the optical signal is split into two parts: one part continues to propagate along the main waveguide 106 and is amplified before being output; the other part enters the branch waveguide 104 through the Y-branch structure and is finally transmitted to the photodiode 105. After receiving the optical signal, the photodiode 105 converts the optical signal into an electrical signal, thereby realizing real-time monitoring of the output optical power of the semiconductor laser 102.

[0067] The semiconductor laser 102 employs a distributed feedback structure, featuring single-mode output, narrow linewidth, and stable wavelength. The active region of the semiconductor laser 102 utilizes a multi-quantum-well structure, with the gain medium being an InGaAsP / InP material system, and an operating wavelength of 1550 nm. The semiconductor laser 102 has a length of 500 μm, a width of 2 μm, a threshold current of 20 mA, an operating current of 100 mA, and an output power of 20–30 mW.

[0068] The semiconductor optical amplifier 103 uses the same material system as the semiconductor laser 102, with a length of 300 μm and a width of 2 μm. The semiconductor optical amplifier 103 operates at a current of 50 mA and provides approximately 6 dB of optical gain. The main waveguide 106 and branch waveguide 104 of the semiconductor optical amplifier 103 form a Y-branch structure with a branch ratio of 9:1, meaning that 90% of the light continues to propagate along the main waveguide 106, and 10% of the light enters the branch waveguide 104.

[0069] Branch waveguide 104 has a length of 100 μm and a width of 1.5 μm, and its branch angle with the main waveguide 106 is 45°. Branch waveguide 104 uses the same material system and structure as the main waveguide 106, but no current is injected into it; it is used only as an optical waveguide.

[0070] The photodiode 105 employs a PIN structure, and its active region material is the same material system as that of the semiconductor laser 102, with a responsivity of 0.8 A / W. The photodiode 105 has dimensions of 50 μm × 50 μm, a dark current of less than 10 nA, and a bandwidth greater than 1 GHz.

[0071] The photodiode 105 and the semiconductor laser 102 use the same material system to avoid heterogeneous integration and reduce process complexity; different materials can also be used for integration, such as InGaAs / InP and InGaAsP / InP.

[0072] The electrically isolated region is formed by ion implantation or grooving, with a resistance greater than 10kΩ, ensuring electrical isolation between the semiconductor laser 102, the semiconductor optical amplifier 103, and the photodiode 105, so that the three can be controlled independently.

[0073] The fabrication process of the semiconductor device integrating the branched waveguide and photodiode includes: firstly, epitaxially growing a multi-quantum-well active region and a waveguide layer on an InP semiconductor substrate; then forming a waveguide structure through photolithography and etching, i.e. forming a Y-branch structure on the semiconductor optical amplifier 103; next, regrowing to form a buried heterojunction; subsequently forming electrodes and electrically isolated regions; and finally, dicing and packaging.

[0074] The integrated branch waveguide and photodiode semiconductor device has the following advantages: First, integrating the semiconductor laser 102, semiconductor optical amplifier 103, branch waveguide 104, and photodiode 105 on the same semiconductor substrate greatly reduces the device size and improves integration density; second, the Y-branch structure enables real-time monitoring of the laser output power without the need for an additional external photodetector; third, the electrically isolated region allows each functional unit to be controlled independently, improving the system's flexibility and reliability; finally, the entire structure is compatible with manufacturing processes, enabling mass production and reducing costs.

[0075] Example 2

[0076] like Figure 1 As shown, this embodiment provides a semiconductor device integrating a branched waveguide and a photodiode, including a semiconductor laser 102, a semiconductor optical amplifier 103, and a photodiode 105, all formed on the same semiconductor substrate 101.

[0077] The structure of the semiconductor device integrating the branch waveguide and photodiode is as follows: The output light of the semiconductor laser 102 is transmitted to the semiconductor optical amplifier 103, forming a Y-branch structure on the semiconductor optical amplifier 103. The Y-branch structure includes a main waveguide 106 and a branch waveguide 104. The main waveguide 106 amplifies and outputs part of the light, while the branch waveguide 104 receives another part of the light and transmits it to the photodiode 105. The photodiode 105 performs photoelectric conversion on the received light, thereby monitoring the forward optical power of the semiconductor laser 102.

[0078] Unlike Embodiment 1, in this embodiment, the semiconductor laser 102, semiconductor optical amplifier 103, branch waveguide 104, and photodiode 105 employ a ridge waveguide structure. The semiconductor laser 102 uses a distributed Bragg grating laser structure. The orthographic projection of the semiconductor laser 102 onto the semiconductor substrate is strip-shaped. One end of the semiconductor laser 102 is connected to the semiconductor optical amplifier 103; at the contact point between the semiconductor laser 102 and the semiconductor optical amplifier 103, their widths are the same, and the bending angle of the semiconductor optical amplifier 103 is 15°. The orthographic projection of the semiconductor optical amplifier 103 onto the semiconductor substrate is conical, gradually increasing in width from 2μm at the connection point with the semiconductor laser 102 to 3μm at the output end. A branch waveguide 104 is formed on one side of the semiconductor optical amplifier 103; the branch waveguide 104 and the main waveguide 106 constitute a Y-branch structure, and the waveguide angle between the branch waveguide 104 and the semiconductor laser 102 is 30°. The position, angle, and width of the branch waveguide 104 can be adjusted according to actual needs to achieve different beam splitting ratios, thereby adjusting the optical power entering the photodiode 105. The orthographic projection shape of the photodiode 105 on the semiconductor substrate is circular.

[0079] The semiconductor device integrating the branch waveguide and photodiode also includes an electrically isolated region. An electrically isolated region is provided between the semiconductor laser 102, the semiconductor optical amplifier 103 and the photodiode 105, so that the three can be independently controlled by current or voltage.

[0080] The semiconductor device integrating the branched waveguide and photodiode operates on the same principle as in Example 1, but its performance characteristics differ due to the use of different structures and parameters.

[0081] The semiconductor laser 102 employs a distributed Bragg grating structure, resulting in a narrower linewidth and a higher side-mode suppression ratio. The active region of the semiconductor laser 102 utilizes a strained quantum well structure, with the gain medium being an AlGaInAs / InP material system, and an operating wavelength of 1310 nm. The semiconductor laser 102 has a length of 600 μm, a width of 2.5 μm, a threshold current of 15 mA, an operating current of 80 mA, and an output power of 20–30 mW.

[0082] The semiconductor optical amplifier 103 adopts a tapered structure, which is beneficial for improving optical coupling efficiency and reducing reflection. The semiconductor optical amplifier 103 has a length of 400 μm, an incident end width of 2.5 μm, and an output end width of 3 μm. The semiconductor optical amplifier 103 operates at a current of 70 mA and provides approximately 8 dB of optical gain. The main waveguide 106 and the branch waveguide 104 of the semiconductor optical amplifier 103 form a Y-branch structure with a branch ratio of 8:2, meaning that 80% of the light continues to propagate along the main waveguide 106, and 20% of the light enters the branch waveguide 104.

[0083] Branch waveguide 104 has a length of 150 μm and a width of 2 μm, and its branch angle with the main waveguide 106 is 30°. Branch waveguide 104 uses the same material system and structure as the main waveguide 106, but no current is injected into it; it is used only as an optical waveguide.

[0084] The photodiode 105 has a circular structure with a diameter of 80 μm. The active region material is the same material system as that of the semiconductor laser 102. It has a responsivity of 0.9 A / W, a dark current of less than 5 nA, and a bandwidth of more than 2 GHz.

[0085] The electrical isolation region is formed by deep trenching, with a resistance greater than 20kΩ, ensuring electrical isolation between the semiconductor laser 102, the semiconductor optical amplifier 103, and the photodiode 105, so that the three can be controlled independently.

[0086] The fabrication process of this semiconductor device integrating branched waveguides and photodiodes includes: firstly, epitaxially growing a multi-quantum-well active region and a waveguide layer on an InP semiconductor substrate; then defining a grating structure by electron beam lithography; next, forming a ridge waveguide structure by lithography and etching; subsequently depositing a passivation layer and forming electrodes; and finally forming, dicing, and packaging an electrically isolated region.

[0087] Example 3

[0088] like Figure 1 As shown, this embodiment provides a semiconductor device integrating a branched waveguide and a photodiode, including a semiconductor laser 102, a semiconductor optical amplifier 103, and a photodiode 105, all formed on the same semiconductor substrate 101.

[0089] The structure of the semiconductor device integrating the branch waveguide and photodiode is as follows: The output light of the semiconductor laser 102 is transmitted to the semiconductor optical amplifier 103, forming a Y-branch structure on the semiconductor optical amplifier 103. The Y-branch structure includes a main waveguide 106 and a branch waveguide 104. The main waveguide 106 amplifies and outputs part of the light, while the branch waveguide 104 receives another part of the light and transmits it to the photodiode 105. The photodiode 105 performs photoelectric conversion on the received light, thereby monitoring the forward optical power of the semiconductor laser 102.

[0090] Unlike the previous two embodiments, in this embodiment, the semiconductor laser 102, semiconductor optical amplifier 103, branch waveguide 104, and photodiode 105 employ a buried heterojunction waveguide structure. The semiconductor laser 102 adopts a Fabry-Perot laser structure. The orthographic projection of the semiconductor laser 102 onto the semiconductor substrate is strip-shaped. One end of the semiconductor laser 102 is connected to the semiconductor optical amplifier 103. At the contact point between the semiconductor laser 102 and the semiconductor optical amplifier 103, their widths are the same, and the bending angle of the semiconductor optical amplifier 103 is 0° (i.e., a straight structure). The orthographic projection of the semiconductor optical amplifier 103 onto the semiconductor substrate is an inverted cone shape, gradually decreasing in width from 3μm at the connection point with the semiconductor laser 102 to 2μm at the output end. A branch waveguide 104 is formed on one side of the semiconductor optical amplifier 103. The branch waveguide 104 and the main waveguide 106 constitute a Y-branch structure, and the waveguide angle between the branch waveguide 104 and the semiconductor laser 102 is 60°. The position, angle, and width of the branch waveguide 104 can be adjusted according to actual needs to achieve different beam splitting ratios, thereby adjusting the optical power entering the photodiode 105. The orthographic projection shape of the photodiode 105 on the semiconductor substrate is polygonal (hexagonal).

[0091] The semiconductor device integrating the branch waveguide and photodiode also includes an electrically isolated region. An electrically isolated region is provided between the semiconductor laser 102, the semiconductor optical amplifier 103 and the photodiode 105, so that the three can be independently controlled by current or voltage.

[0092] The semiconductor device integrating the branched waveguide and photodiode operates on the same principle as the previous two embodiments, but its performance characteristics differ due to the use of different structures and parameters.

[0093] Semiconductor laser 102 employs a Fabry-Perot structure, exhibiting multimode output characteristics, making it suitable for applications requiring broad-spectrum output. The active region of semiconductor laser 102 utilizes a semiconductor quantum well structure, with the InGaAsP / InP material system as the gain medium, and an operating wavelength of 1480 nm. Semiconductor laser 102 has a length of 400 μm and a width of 3 μm, with cavity mirrors formed by coatings on both end faces, exhibiting reflectivities of 95% and 30%, respectively. The threshold current of semiconductor laser 102 is 25 mA, the operating current is 120 mA, and the output power is 20 mW.

[0094] The semiconductor optical amplifier 103 adopts an inverted conical structure, which is beneficial for controlling mode distribution and reducing reflection. The semiconductor optical amplifier 103 has a length of 350 μm, an incident end width of 3 μm, and an output end width of 2 μm. The semiconductor optical amplifier 103 operates at a current of 60 mA and provides approximately 7 dB of optical gain. The main waveguide 106 and branch waveguide 104 of the semiconductor optical amplifier 103 form a Y-branch structure with a branch ratio of 7:3, meaning that 70% of the light continues to propagate along the main waveguide 106, and 30% of the light enters the branch waveguide 104.

[0095] Branch waveguide 104 has a length of 120 μm and a width of 2.5 μm, and its branch angle with the main waveguide 106 is 60°. Branch waveguide 104 uses the same material system and structure as the main waveguide 106, but no current is injected into it; it is used only as an optical waveguide.

[0096] The photodiode 105 adopts a hexagonal structure with a diagonal length of 100 μm. The active region material is the same material system as that of the semiconductor laser 102. It has a responsivity of 0.85 A / W, a dark current of less than 8 nA, and a bandwidth of greater than 1.5 GHz. The hexagonal structure is beneficial for improving light absorption efficiency and reducing parasitic capacitance.

[0097] The electrically isolated region is formed by a combination of ion implantation and grooving, with a resistance greater than 15kΩ, ensuring electrical isolation between the semiconductor laser 102, the semiconductor optical amplifier 103, and the photodiode 105, so that the three can be controlled independently.

[0098] The fabrication process of this semiconductor device integrating a branch waveguide and a photodiode includes: firstly, epitaxially growing a multi-quantum-well active region and a waveguide layer on an InP semiconductor substrate; then forming a waveguide structure through photolithography and etching; next, regrowing to form a buried heterojunction; subsequently forming electrodes and electrically isolated regions; and finally, end-face coating, dicing, and packaging.

[0099] It should be noted that Embodiment 1, Embodiment 2, and Embodiment 3 are all types of semiconductor devices that integrate branched waveguides and photodiodes.

[0100] Through Examples 1, 2, and 3, it can be concluded that the semiconductor device integrating branch waveguide and photodiode provided in this application integrates photodiode 105, semiconductor optical amplifier 103, and semiconductor laser 102 monolithically through the coupling of branch waveguide 104, thereby ensuring the integrity of the main optical path of the laser while constructing an auxiliary monitoring optical path.

[0101] Figure 2 The light field distribution of the semiconductor device integrating a branched waveguide and a photodiode in Embodiment 1 of this application is shown at different locations in the cavity.

[0102] like Figure 2 As shown, the output light of the semiconductor laser 102 is split into two after passing through the Y-branch structure. One part of the light is output along the main waveguide 106 of the semiconductor optical amplifier 103, and the other part is transmitted to the photodiode 105 via the branch waveguide 104.

[0103] Figure 3 The splitting ratio is the Y-branch structure of the semiconductor device integrating branched waveguides and photodiodes in Embodiment 1 of this application.

[0104] like Figure 3 As shown, the output light of the semiconductor laser 102 is split into two by the Y-branch structure, wherein the light field intensity in the branch waveguide 104 is 22% of that in the main waveguide 106. Specifically, the waveguide angle θ between the branch waveguide 104 and the semiconductor laser 102 and the width of the branch waveguide 104 can be designed according to actual needs to obtain the required splitting ratio.

[0105] For example, the safe operating area (SOA) uses a curved waveguide of equal width, 3 μm, with a bending angle of 8° and a bending radius of 1000 μm. When the intersection of branch waveguide 104 is located at 2 / 3 of the horizontal direction of the SOA, the width of branch waveguide 104 is 1.5 μm. The relationship between the waveguide angle θ and the ratio of the optical field intensity in branch waveguide 104 to the optical field intensity in the main waveguide is as follows: Figure 4 As shown. SOA refers to the voltage and current range within which semiconductor devices (such as transistors and diodes) can operate safely and reliably.

[0106] For example, when the waveguide angle θ is set to 75°, the relationship between the width of the branch waveguide 104 and the ratio of the optical field intensity in the branch waveguide 104 to the optical field intensity in the main waveguide is as follows: Figure 5 As shown.

[0107] Therefore, the position, angle, and width of the branch waveguide 104 can be adjusted according to actual needs to achieve different splitting ratios. Thus, the semiconductor device integrating a branch waveguide and a photodiode provided in this application can achieve real-time and accurate monitoring of the laser's output optical power, providing reliable data support for system closed-loop control; the photodiode 105 monitors the front optical power of the semiconductor laser 102 with high precision and high linearity; the waveguide-coupled semiconductor laser 102 with integrated photodiode 105, through its high integration design, helps enhance the stability and reliability of the system in applications such as optical interconnect modules, optical I / O chips, and co-packaged optics.

[0108] The fabrication method for semiconductor devices integrating branched waveguides and photodiodes is consistent with the fabrication process of conventional BH semiconductor lasers or ridge waveguide semiconductor lasers. Generally, heterogeneous integration is not required, meaning the material structure / system of semiconductor laser 102, semiconductor optical amplifier 103, and photodiode 105 must be identical. Heterogeneous integration is also possible; for example, semiconductor laser 102, semiconductor optical amplifier 103, and photodiode 105 can be designed independently, which is beneficial for improving performance.

[0109] It should also be noted that directional terms mentioned in the embodiments, such as "up," "down," "front," "back," "left," and "right," are only for reference to the directions in the accompanying drawings and are not intended to limit the scope of protection of this application. Throughout the drawings, the same elements are represented by the same or similar reference numerals. Conventional structures or constructions will be omitted where they may cause confusion in understanding this application. Furthermore, the shapes and sizes of the components in the drawings do not reflect actual size and proportion, but only illustrate the content of the embodiments of this application. Moreover, the word "comprising" does not exclude the presence of elements or steps not listed in the claims. The word "a" or "an" preceding an element does not exclude the presence of a plurality of such elements.

[0110] Similarly, it should be understood that, in order to simplify this application and aid in understanding one or more of the various aspects of the invention, in the description of exemplary embodiments of this application above, various features of this application are sometimes grouped together into a single embodiment, figure, or description thereof.

[0111] The above specific embodiments further illustrate the purpose, technical solution and beneficial effects of this application. It should be understood that the above are only specific embodiments of this application and are not intended to limit this application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A semiconductor device integrating a branch waveguide and a photodiode, characterized by, The application relates to a semiconductor laser, a semiconductor optical amplifier and a photodiode formed on the same semiconductor substrate. The output light of the semiconductor laser is transmitted to the semiconductor optical amplifier, a Y-branch structure is formed in the active gain region of the semiconductor optical amplifier, the Y-branch structure comprises a main waveguide and a branch waveguide, the main waveguide amplifies part of the output light, the branch waveguide receives another part of the light and transmits the light into the photodiode, the photodiode photoelectrically converts the received light and is used for monitoring the forward light power of the semiconductor laser. One end of the semiconductor laser is connected to the semiconductor optical amplifier; the contact part of the semiconductor laser and the semiconductor optical amplifier has the same width, and the bending angle of the semiconductor optical amplifier ranges from 0 to 50 degrees. The included angle between the branch waveguide and the waveguide of the semiconductor laser ranges from 0 to 90 degrees. The position, angle and width of the branch waveguide can be adjusted according to actual requirements, different light splitting ratios are obtained, and the light power entering the photodiode is adjusted. The application further comprises an electrically isolated region; the electrically isolated region is arranged between the semiconductor laser, the semiconductor optical amplifier and the photodiode and is used for independently controlling the current or voltage of the three; the electrically isolated region is formed by combining ion implantation and grooving, and the electric resistance is greater than 15kΩ. The shape of the orthographic projection of the semiconductor optical amplifier on the semiconductor substrate at least comprises a strip, a cone and an inverted cone. The semiconductor laser, the semiconductor optical amplifier, the branch waveguide and the photodiode all adopt a buried heterojunction waveguide or a ridge waveguide structure. The semiconductor laser adopts a distributed feedback laser, a distributed Bragg grating laser or a Fabry-Perot laser.

2. The semiconductor device of claim 1, wherein, The shape of the orthographic projection of the semiconductor laser on the semiconductor substrate at least comprises a strip.

3. The semiconductor device of claim 1, wherein, The shape of the orthographic projection of the photodiode on the semiconductor substrate at least comprises a strip, a polygon, a circle and an ellipse.

4. The semiconductor device of claim 1, wherein, ​

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