Wide tuning narrow linewidth semiconductor laser

Abstract

The application provides a wide tuning narrow line width semiconductor laser, characterized by comprising: an optical gain module for providing a tunable light wave; an optical coupling module for coupling the light wave; and an external cavity resonance module for adjusting the coupled light wave to obtain a narrow line width output light. The application provides a wide tuning narrow line width semiconductor laser which utilizes Fano resonance between a micro-ring resonator and a U-shaped waveguide and vernier scale effect between micro-ring resonators to realize a tuning function, and utilizes a Mach-Zehnder interferometer to suppress side modes in a transmission spectrum of the micro-ring resonator, thereby improving wavelength selectivity. The application realizes narrow line width, frequency stability and wide spectrum range of the output laser.

Description

Technical Field

[0001] This invention relates to the field of optoelectronics technology, and mainly to a wide-tuning, narrow-linewidth semiconductor laser. Background Technology

[0002] Narrow-linewidth semiconductor lasers are widely used in various fields due to their advantages of high coherence, low phase noise, and high frequency stability. Today, they are frequently used as core components in ultra-high-speed optical communication, long-distance space laser communication, ultra-high-resolution lidar, and optical sensing. With the development of technologies such as high-quality factor optical resonators and heterogeneous integrated chips, narrow-linewidth semiconductor lasers have undergone revolutionary development in the past decade, with linewidths compressed to the kilohertz level and even the sub-kilohertz level.

[0003] Currently, most narrow-linewidth semiconductor lasers in use are distributed feedback and distributed Bragg reflector monolithic integrated lasers. The linewidth of these lasers is limited by factors such as resonant cavity length and losses, and their fabrication process is relatively complex, making large-scale production and application difficult. How to achieve a wide tuning range and high stability laser output while ensuring narrow linewidth output remains a challenge. Summary of the Invention

[0004] (a) Technical problems to be solved

[0005] The present invention provides a wide-tunable narrow-linewidth semiconductor laser, which at least partially solves one of the above-mentioned technical problems.

[0006] (II) Technical Solution

[0007] This invention provides a wide-tunable narrow-linewidth semiconductor laser, comprising: an optical gain module for providing tunable optical waves; an optical coupling module for coupling optical waves; and an external cavity resonator module for adjusting the coupled optical waves to obtain narrow-linewidth output light.

[0008] Optionally, the optical gain module may employ a reflective semiconductor optical amplifier or a gain chip.

[0009] Optionally, the optical coupling module includes a mode converter located at the connection between the optical gain module and the external cavity resonator module, used to couple optical waves into the external cavity resonator module.

[0010] Optionally, the external cavity resonant module includes: a U-shaped waveguide for generating Fano resonance in the light wave; a micro-ring resonator for improving the Q factor in the resonance mode and performing wavelength tuning; and a Mach-Zehnder interferometer for suppressing side modes of the light wave output by the micro-ring resonator and outputting a narrow linewidth light wave.

[0011] Optionally, the microring resonator consists of a conventional microring resonator and a grating resonator, wherein the grating resonator is composed of an array of air holes.

[0012] Optionally, a thermoelectric electrode is placed at the microring of the microring resonator. The thermoelectric electrode is used to adjust the temperature of the microring resonator to change the waveguide refractive index.

[0013] Optionally, the waveguide coupling in the microring resonator is curved waveguide coupling.

[0014] Alternatively, the Mach-Zehnder interferometer can be a symmetric Mach-Zehnder interferometer or an asymmetric Mach-Zehnder interferometer.

[0015] Optionally, the external cavity resonant module also includes a ring mirror for feeding back the light wave output from the Mach-Zehnder interferometer to the optical gain module, thereby increasing the effective length of the external cavity of the wide-tunable, narrow-linewidth semiconductor laser.

[0016] Optionally, the external cavity resonator module is quasi-monolithically integrated from a photonic chip and a semiconductor gain chip.

[0017] (III) Beneficial Effects

[0018] The wide-tunable, narrow-linewidth semiconductor laser provided by this invention has at least the following beneficial effects:

[0019] 1. The wide-tunable, narrow-linewidth semiconductor laser provided by this invention utilizes the Fano resonance between the microring resonator and the U-shaped waveguide, and the vernier caliper effect between the microring resonators, to achieve tuning functionality. Furthermore, a Mach-Zehnder interferometer is used to suppress side modes in the transmission spectrum of the microring resonator, improving wavelength selectivity. This achieves narrowed linewidth, stable frequency, and rapid tuning over a wide spectral range for the output laser.

[0020] 2. The wide-tuning narrow-linewidth semiconductor laser external cavity resonant module provided by the present invention is quasi-monolithically integrated with a photonic chip and a semiconductor gain chip. The manufacturing process is simple and can achieve the effects of compact structure and high stability. Attached Figure Description

[0021] Figure 1 The schematic diagram illustrates the structure of a wide-tunable narrow-linewidth semiconductor laser according to an embodiment of the present invention;

[0022] Figure 2 A schematic diagram of the microring resonator in an embodiment of the present invention is shown.

[0023] Figure 3 The schematic diagram illustrates the structure of a wide-tunable narrow-linewidth semiconductor laser according to an embodiment of the present invention;

[0024] Figure 4The schematic diagram illustrates the structure of a wide-tunable narrow-linewidth semiconductor laser according to an embodiment of the present invention;

[0025] Figure 5 The diagram schematically illustrates the structure of a wide-tunable narrow-linewidth semiconductor laser according to an embodiment of the present invention.

[0026] Explanation of reference numerals in the attached figures:

[0027] 1-Reflective semiconductor optical amplifier; 2-Mode converter; 3-U-shaped waveguide; 4-Micro-ring resonator; 5-Thermoelectrode; 6-Mach-Zehnder interferometer; 7-Ring mirror. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments and the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0029] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the invention. The terms “comprising,” “including,” etc., as used herein indicate the presence of the stated features, steps, operations, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, or components.

[0030] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0031] In the description of this invention, it should be understood that the terms "longitudinal", "length", "circumferential", "front", "rear", "left", "right", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the subsystem or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0032] Throughout the accompanying drawings, identical elements are represented by the same or similar reference numerals. Conventional structures or configurations may be omitted where they might cause confusion in understanding the invention. Furthermore, the shapes, sizes, and positional relationships of the components in the drawings do not reflect actual size, scale, or actual positional relationships. Additionally, any reference numerals placed between parentheses in the claims should not be construed as limiting the claims.

[0033] Similarly, to simplify the invention and aid in understanding one or more of the various disclosed aspects, in the above description of exemplary embodiments of the invention, various features of the invention are sometimes grouped together into a single embodiment, figure, or description thereof. The use of terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicates that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0034] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0035] The purpose of this invention is to provide a microwave frequency measurement system that enables, for example, high-precision measurement of microwave frequencies.

[0036] The present invention will be further described in detail below with reference to specific embodiments and the accompanying drawings.

[0037] One embodiment of the present invention provides a wide-tunable narrow-linewidth semiconductor laser, comprising: an optical gain module, an optical coupling module, and an external cavity resonator module.

[0038] Figure 1 The diagram schematically illustrates the structure of a wide-tunable narrow-linewidth semiconductor laser according to an embodiment of the present invention.

[0039] like Figure 1 As shown, the optical gain module is used to provide tunable light waves and employs a reflective semiconductor optical amplifier 1 or a gain chip. The gain chip can be, for example, a high-power indium phosphide (InP) gain chip or a high-power indium gallium arsenide phosphide (InGaAsP) gain chip.

[0040] An optical coupling module, used to couple the light waves provided by the optical gain module, is located at the connection between the optical gain module and the external cavity resonator module. The optical coupling module can be a mode converter 2, used to couple the light waves from the optical gain module into the external cavity resonator module. In this embodiment, the mode converter can be a double-layer inverted cone mode converter. Furthermore, besides the mode converter provided in this embodiment, the optical wave coupling method can also be lens coupling, photon lead stitching, etc. Those skilled in the art can choose according to the actual situation; this invention does not limit the choice.

[0041] An external cavity resonant module is used to modulate the coupled light wave to obtain narrow linewidth output light. In the present invention, the external cavity resonant module may include a U-shaped waveguide 3, a micro-ring resonator 4, and a Mach-Zehnder interferometer 6.

[0042] like Figure 2 As shown, in this embodiment of the invention, the microring resonator 4 is a grating-assisted microring resonator, consisting of a conventional microring resonator and a grating resonator composed of an array of air holes. The microring resonator 4 can be constructed from a silicon (SOI) waveguide microring resonator on an insulating substrate or a high-quality silicon nitride (Si3N4) / silicon dioxide (SiO2) waveguide microring resonator.

[0043] In this embodiment of the invention, the vernier effect is utilized, when the grating resonator satisfies the resonance condition L·n g_eff =m g λ g When this occurs, a lasing wavelength will be generated; where λ g The resonant wavelength of the grating resonator, n g_eff The effective refractive index of the grating resonator, m g The resonant order of the cavity is given. In this embodiment of the invention, a thermoelectric electrode 5 is placed at the micro-ring of the micro-ring resonator 4. The temperature of the micro-ring resonator 4 is adjusted using the thermoelectric electrode, and the waveguide refractive index is changed by controlling the current of the thermoelectric electrode 5, thereby achieving wavelength adjustment. This micro-ring resonator structure can effectively improve the Q-factor in the resonant mode of the grating resonator, enhance the interaction between light and matter, and obtain a narrower linewidth.

[0044] The waveguide coupling in the microring resonator 4 is performed using curved waveguide coupling, which effectively improves the coupling coefficient compared to straight waveguide coupling. In this embodiment, the curved waveguide angle is 90°, the coupling gap is 130nm, resulting in high cross-coupling efficiency, and the curved waveguide width is 400nm. The ring waveguide radius is set to 4.5µm, and the ring waveguide width is 450nm. The number of microring resonators 4 can be one, two, or more.

[0045] The Mach-Zendel interferometer 6 can be a symmetrical Mach-Zendel interferometer (MZI) or an asymmetrical Mach-Zendel interferometer (MZI). MZI minimizes transmittance at the nearest neighbor wavelength, resulting in higher wavelength selectivity in the waveguide loop. The symmetry of MZI affects the linewidth of the external cavity laser.

[0046] In this embodiment of the invention, the Mach-Zehnder interferometer (MZI) selected is a highly asymmetric MZI. By setting it up, the transmittance of the MZI is maximized at the resonant wavelength of the microring resonator. By suppressing the side modes in the transmission spectrum of the microring resonator, the wavelength selectivity is effectively improved.

[0047] Figure 4 The diagram schematically illustrates the structure of a wide-tunable narrow-linewidth semiconductor laser according to an embodiment of the present invention. Figure 4 Taking a grating-assisted microring resonator and an asymmetric MZI as an example, by nesting the microring resonator 4 in a U-shaped feedback coupling waveguide, a Fano resonance is generated between the U-shaped waveguide 3 and the microring resonator 4, forming a Fano resonator with a grating-assisted microring structure. By heating the grating-assisted microring, the light wave can be switched between preset wavelengths. When the light passes through the grating-assisted microring and the asymmetric MZI, the output light achieves narrowed linewidth, wide tuning, and frequency stability.

[0048] In this embodiment of the invention, a grating-assisted microring resonator is nested within a U-shaped feedback coupling waveguide, achieving tuning functionality based on the Fano resonance between the microring and the U-shaped waveguide and the vernier caliper effect between the microrings. Furthermore, a curved waveguide is employed at the coupling point to increase the coupling efficiency between the microring and the waveguide. MZI effectively suppresses side modes in the transmission spectrum of the ring resonator, thereby significantly improving wavelength selectivity.

[0049] Furthermore, in this embodiment, the external cavity resonant module may also include a ring mirror 7, such as... Figure 3 and Figure 5 As shown, the ring mirror 7 is used to feed the light wave output from the Mach-Zehnder interferometer 6 back to the optical gain module, increasing the effective length of the external cavity of the wide-tunable, narrow-linewidth semiconductor laser, and obtaining a narrower linewidth without increasing the waveguide size.

[0050] In this embodiment of the invention, the external cavity resonant module includes waveguide structures formed on various substrates such as silicon (Si)-based or indium phosphide (InP)-based. By utilizing quasi-monolithic integration of photonic chips and semiconductor gain chips, a compact structure and high stability can be achieved.

[0051] The wide-tunable, narrow-linewidth semiconductor laser provided by this invention has advantages such as low noise, high side-mode rejection ratio, high temperature stability, simple structure, and low cost. By quasi-monolithically integrating the gain chip and the external cavity chip, it combines the high reliability and low power consumption characteristics of a monolithic integrated structure.

[0052] The specific embodiments described above provide a further detailed explanation of the technical solution of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A wide-tuning, narrow-linewidth semiconductor laser, characterized in that, include: Optical gain module, used to provide tunable light waves; An optical coupling module is used to couple the light waves; An external cavity resonant module is used to adjust the coupled light wave to obtain narrow linewidth output light; The external cavity resonant module includes: a U-shaped waveguide (3) for generating Fano resonance in the light wave; The micro-ring resonator (4) is used to improve the Q factor in the resonance mode and perform wavelength tuning; the micro-ring resonator (4) is composed of a conventional micro-ring resonator and a grating resonator, wherein the grating resonator is composed of an array of air holes; The Mach-Zehnder interferometer (6) is used to suppress the side modes of the light wave output by the micro-ring resonator (4) and output a narrow linewidth light wave. By nesting the micro-ring resonator (4) in the U-shaped feedback coupling waveguide, Fano resonance is generated between the U-shaped waveguide (3) and the micro-ring resonator (4), forming a grating-assisted micro-ring structure Fano resonator. By heating the grating-assisted micro-ring, the light wave can be switched between preset wavelengths.

2. The wide-tuning, narrow-linewidth semiconductor laser according to claim 1, characterized in that, The optical gain module adopts a reflective semiconductor optical amplifier (1) or a gain chip.

3. The wide-tuning, narrow-linewidth semiconductor laser according to claim 1, characterized in that, The optical coupling module includes: The mode converter (2) is located at the connection between the optical gain module and the external cavity resonator module, and is used to couple the optical wave into the external cavity resonator module.

4. The wide-tuning, narrow-linewidth semiconductor laser according to claim 1, characterized in that, The microring resonator (4) has a thermoelectric electrode (5) placed at the microring. The thermoelectric electrode (5) is used to adjust the temperature of the microring resonator (4) and change the waveguide refractive index.

5. The wide-tuning, narrow-linewidth semiconductor laser according to claim 1, characterized in that, The waveguide coupling method in the microring resonator (4) is curved waveguide coupling.

6. The wide-tuning, narrow-linewidth semiconductor laser according to claim 1, characterized in that, The Mach-Zehnder interferometer (6) is either a symmetrical Mach-Zehnder interferometer or an asymmetrical Mach-Zehnder interferometer.

7. The wide-tuning, narrow-linewidth semiconductor laser according to claim 1, characterized in that, The external cavity resonant module also includes: A ring mirror (7) is used to feed back the light wave output by the Mach-Zehnder interferometer (6) to the optical gain module, thereby increasing the effective length of the external cavity of the wide-tunable narrow-linewidth semiconductor laser.

8. The wide-tunable, narrow-linewidth semiconductor laser according to claim 1, characterized in that, The external cavity resonant module is a quasi-monolithic integration of a photonic chip and a semiconductor gain chip.

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