43 results about "Waveguide amplifier" patented technology

The invention discloses a circular optical waveguide amplifier and a preparation method thereof, and belongs to the technical field of polymer optical waveguide amplifiers. The circular optical waveguide amplifier sequentially comprises a silicon substrate (1), a silicon dioxide lower cladding (2), an active polymer core layer (3) doped with rare earth nanoparticles and an upper cladding (4) from bottom to top. The preparation method comprises the steps of growing and cleaning the silicon dioxide lower cladding (2), preparing a core layer solution, preparing the active polymer core layer (3), processing the circular waveguide structure with the bracket, forming the upper cladding (4) and the like. In order to solve the problem of coupling mismatch of a traditional rectangular-section waveguide and a round optical fiber end face, the invention provides a waveguide structure with a round section, so that the overlapping degree of the waveguide with the round section and an optical fiber light field is maximized, effective coupling of an optical fiber mode and a waveguide mode is realized, coupling loss is reduced, and gain is further improved.

An optical device comprises a Praseodymium (Pr)-dope waveguide optical amplifier capable of amplifying O-band light. The waveguide optical amplifier may be formed on the substrate (e.g., silicone or glass) and comprises a core defining an optical path through the waveguide optical amplifier, and cladding abutting at least one side of the core. The core comprises a silicon-based material, such as silicon nitride (Si3N4), doped with Praseodymium (Pr) such that, on condition of pump light and O-band signal light being passed through the waveguide optical amplifier, the waveguide optical amplifier amplifies the O-band signal light.

The invention relates to a thin film lithium niobate-based heterogeneous integrated optical waveguide amplifier chip and a preparation method thereof, the thin film lithium niobate-based heterogeneous integrated optical waveguide amplifier chip comprises a silicon substrate layer, a lower cladding layer, a thin film lithium niobate waveguide layer, an interval cladding layer and a rare earth ion doped gain thin film layer which are sequentially stacked from bottom to top, and the interval cladding layer extends to the lower cladding layer; and the thin-film lithium niobate waveguide layer is coated by the interval cladding. The heterogeneous integrated optical waveguide amplifier chip comprises a thin film lithium niobate (TFLN) waveguide layer and a rare earth ion doped gain thin film layer on the top of the TFLN waveguide layer, and an interval wrapping layer is arranged between the TFLN waveguide layer and the rare earth ion doped gain thin film layer for separation. Wherein the rare earth ion doped gain thin film layer provides optical gain, the TFLN waveguide layer can realize mode constraint, most optical modes can be switched between the rare earth ion doped gain thin film layer and the TFLN waveguide layer only by changing the width of a TFLN strip-shaped waveguide, and high-performance broadband amplification is realized. The photonic integrated circuit has the advantages of wide gain bandwidth, high gain efficiency and good compatibility with the existing photonic integrated circuit.

The invention relates to an erbium-doped thin film lithium niobate heterogeneous integrated optical waveguide amplifier and a preparation method thereof, the optical waveguide amplifier comprises a substrate layer, a silicon dioxide buried oxide layer, an erbium-doped thin film lithium niobate layer, a silicon-rich silicon nitride layer and an upper cladding layer which are sequentially stacked from bottom to top, and the erbium-doped thin film lithium niobate layer and the silicon-rich silicon nitride layer form a composite waveguide. By regulating and controlling the width of the silicon-rich silicon nitride waveguide, the high-power optical waveguide amplifier with a single mode and a large mode volume can be realized, and the multi-mode crosstalk effect can be effectively inhibited. The invention further discloses a preparation method of the erbium-doped thin film lithium niobate heterogeneous integrated optical waveguide amplifier. According to the preparation method of the waveguide amplifier, the silicon-rich silicon nitride waveguide only needs to be etched through single-step exposure, and the problems of etching loss and process consistency existing in the currently reported preparation process of the thin-film lithium niobate optical waveguide amplifier are effectively solved. The scheme provided by the invention has remarkable advantages in the aspects of manufacturing cost, process stability and gain performance of the optical waveguide amplifier.

The invention provides a near self-similarity amplification flat light frequency comb based on a rare earth doped gain nonlinear optical waveguide, and belongs to the technical field of light frequency combs. A pulse light source generates a light frequency comb seed light source; the pulse compression unit is used for compressing chirped pulses of the optical pulses; the pulse shaping unit is used for shaping the compressed pulse; according to the normal dispersion rare earth doped nonlinear optical waveguide amplifier, rare earth doped ions are injected / doped into a normal dispersion nonlinear optical waveguide, and the waveguide amplifier is formed under the pumping action of pumping laser with the corresponding proper wavelength. The near self-similar amplification process evolution of the light pulse is realized in the normal dispersion rare earth doped nonlinear optical waveguide amplifier based on the combined action of normal dispersion, gain, self-phase modulation and light wave splitting. The near self-similarity amplification evolution process of the light pulse in the normal dispersion rare earth doped nonlinear optical waveguide amplifier is utilized, and the performance of the output light frequency comb in the aspects of flatness and flat bandwidth can be effectively improved.

An erbium-ytterbium co-doped polymer composite structure core layer optical waveguide amplifier belongs to the technical field of polymer optical waveguide amplifiers. It is composed of a silicon substrate, a silica lower cladding layer, a low-loss polymer core layer, an erbium-ytterbium co-doped polymer gain layer, and a polymethyl methacrylate upper cladding layer in sequence; the low-loss polymer core layer, the erbium-ytterbium co-doped polymer gain layer, and the polymethyl methacrylate upper cladding layer are all located above the silica lower cladding layer, the low-loss polymer core layer is coated in the erbium-ytterbium co-doped polymer gain layer, and the erbium-ytterbium co-doped polymer gain layer is coated in the polymethyl methacrylate upper cladding layer; the low-loss polymer core layer and the erbium-ytterbium co-doped polymer gain layer form a composite structure core layer. The composite structure core layer optical waveguide amplifier designed by the present invention can obtain a greater gain than traditional rectangular waveguide and inverted ridge optical waveguide amplifiers under the conditions of the same waveguide size and waveguide length, further improving the application prospect of the polymer optical waveguide amplifier.

The invention discloses an optical amplifier based on a double-cladding erbium-doped LiNbO3 waveguide. The optical amplifier comprises a double-cladding erbium-doped LiNbO3 optical amplification waveguide and multimode beam combiners at the two ends of the double-cladding erbium-doped LiNbO3 optical amplification waveguide. A bidirectional pumping design is adopted, so that 980nm pumping light is injected from multimode beam splitters at two ends and is converged with 1550nm signal light, and stimulated radiation is generated to amplify the power of the signal light. According to the structure, the pumping energy coupled into the waveguide is increased through the cladding, the overlapping area of a waveguide mode field is increased, and the pumping efficiency is remarkably improved. And the total pumping energy is improved in a multimode transmission mode, so that the overall gain and the output power are improved. The erbium-doped waveguide amplifier has the advantages of high pump light coupling efficiency and high gain, and has wide application prospects in the field of integrated photoelectronics and the field of optical communication.

The application discloses a kind of optical amplifiers based on double-clad doped erbium LiNbO3 waveguide, including double-clad doped erbium LiNbO3 optical amplification waveguide and multimode combiner at its both ends. The design of two-way pumping is used, so that 980nm pumping light is injected from the multimode beam splitter at both ends and converges with 1550nm signal light, to produce stimulated radiation to realize the amplification of signal light power. The structure increases the coupling-in waveguide pump energy through cladding, improves the overlap area of waveguide mode field, and significantly improves the pump efficiency. The total pump energy is improved by multimode transmission mode, so as to improve the overall gain and output power. The doped erbium waveguide amplifier of the application has the advantages of high pump light coupling efficiency and high gain, and has wide application prospect in the field of integrated optoelectronics and optical communication.

A planar waveguide amplifier includes a planar waveguide including a flat plate-like core; a first cladding provided on a first principal face of the core; and a second cladding provided on a second principal face of the core, and signal light and pumping light travel into the planar waveguide so that the signal light and the pumping light propagate inside the core in such a manner that optical paths of the signal light and the pumping light overlap each other, and in a zig-zag manner, and the core is an amplification medium containing a rare-earth element serving as an active ion of a three-level system, and absorbs the signal light on the basis of a reduction in intensity of the pumping light.

The invention relates to a concentration and refractive index coordinated regulation gain equalization optical waveguide amplifier and a preparation method thereof, and belongs to the technical field of polymer optical waveguide amplifiers, the optical waveguide amplifier structurally comprises a substrate (1), an outer core layer (2), an inner core layer (3) and an upper cladding (4); the preparation method comprises the steps of cleaning the substrate, preparing inner and outer core layer solutions, preparing the inner core layer, preparing the outer core layer, preparing the upper cladding and the like. The few-mode optical waveguide amplifier designed by the invention can realize balanced amplification of five signal modes under the condition of single-mode pumping, can compensate for the loss problem caused by an on-chip high-capacity system, and assists in realizing expansion of a communication system.

This invention discloses a laser alarm, comprising an optical receiving system, an optical scanning system, an optical switch, an optical amplification system, a wavelength division detection system, and a signal processing system. The optical system receives incoming laser light and transmits it to the optical scanning system. The optical scanning system uses a micro-mirror to perform the scanning. After passing through the optical switch, visible light signals directly enter the wavelength division detection system, while near-infrared light signals are amplified before entering the system. In this design, the optical switch, optical amplification system, and wavelength division detection system are integrated onto a single silicon photonic chip, including a silicon-based waveguide switch, a silicon-based waveguide amplifier, an arrayed waveguide grating, and a silicon-based photodetector. The signal processing system is connected to the micro-mirror chip and the silicon-based photodetector acquisition card. This invention achieves miniaturization of the laser alarm, enabling rapid detection of threatening laser signals and acquisition of laser azimuth and wavelength information, with high directional accuracy and a low false alarm rate.

The present invention discloses a broadband polymer-based optical waveguide amplifier and a preparation method thereof, belonging to the field of broadband optical communication technology. The method includes preparing multi-layer core-shell rare earth nanoparticles doped with multiple lanthanide luminescent center ions, and preparing a broadband polymer gain medium by physically doping or chemically bonding the multi-layer core-shell rare earth nanoparticles; using the obtained broadband polymer gain medium as the core layer to prepare an optical waveguide amplifier. By co-doping two or more kinds of lanthanide luminescent center ions in the matrix of rare earth nanomaterials, the present invention realizes broadband luminescence of rare earth nanoparticles by constructing a core-shell structure; prepares a polymer-based optical waveguide amplifier capable of realizing optical amplification functions in at least two or more bands, so as to greatly broaden its gain response range. The broadband polymer optical waveguide amplifier prepared by the preparation method of the present invention can amplify optical signal lights of various different wavelengths, and eliminates the limitation of the single gain frequency band of the polymer optical waveguide amplifier.

A system and methods for low noise multi-channel optical signal amplification using an optical parametric amplifier are described. A waveguide etched into a ϰ(2) nonlinear optical material, such as thin film lithium niobate (TFLN), provides confined optical parametric amplification using a pump laser to amplify multi-channel optical signals of lower energy. Noise and crosstalk between channels within the OPA waveguide amplifier can be reduced if the OPA waveguide physical dimensions, along with the optical properties of the waveguide material, are adjusted to create a group velocity mismatch (GVM) between the propagating pump light and the amplified signal channels. OPA waveguide designs with larger GVM reduces crosstalk between modes in the waveguide, reducing noise, as measured by the error vector magnitude (EVM), and improving signal fidelity for the amplified optical signals.

This invention provides an optical waveguide amplifier and a method for fabricating it. The optical waveguide amplifier includes a substrate layer, an insulating layer, a passive waveguide layer, and multiple doped layers. The insulating layers are stacked on the substrate layer. The passive waveguide layer and the multiple doped layers are stacked on the insulating layer. An m-layer doped layer is disposed above the passive waveguide layer, and an n-layer doped layer is disposed below it, where m and n are integers, m+n≥2, and m≥0, n≥0. The multiple doped layers are doped with various rare-earth ions. Compared to fiber amplifiers doped with rare-earth elements, the optical waveguide amplifier in this embodiment is smaller, which simplifies the device structure, reduces device size, and lowers costs. Compared to existing on-chip optical waveguide amplifiers, the optical waveguide amplifier in this embodiment can be doped with various rare-earth ions, enabling the amplification of broadband signals and broadening its applicability.

The invention discloses a C-waveband-oriented erbium-doped AlN optical waveguide amplifier and a preparation method thereof, and relates to the technical field of photonic devices. The amplifier comprises a substrate layer, a buried oxide layer, an erbium-doped aluminum nitride waveguide layer and a silicon dioxide coating layer which are sequentially arranged from bottom to top, wherein the erbium-doped aluminum nitride waveguide layer is a strip-shaped waveguide, and the crystal axis orientation is height c-axis orientation. The problem that the luminous efficiency is low due to the temperature quenching effect of an erbium-doped semiconductor material used by an existing optical waveguide amplifier can be solved, and a feasible scheme is provided for achieving the large-scale, integratable and high-gain optical waveguide amplifier.

Photonic circuit Ti: sapphire optical amplifiers are provided. Key aspects of the technology include near-perfect mode overlap between signal and pump in the amplifier waveguide, and low-loss wavelength division multiplexing for separating / combining signal and pump. Applications include various amplifier configurations, narrow-linewidth photonic circuit lasers, and photonic circuit incoherent amplified spontaneous emission sources.

A photonic circuit Ti: sapphire optical amplifier is provided. Critical aspects of the technique include near perfect mode overlap between the signal and the pump in the amplifier waveguide, and low loss wavelength division multiplexing techniques for separating / combining the signal and the pump. Applications include various amplifier configurations, narrow linewidth photonic circuit lasers, and photonic circuit incoherent amplified spontaneous emission sources.

The invention discloses an optical waveguide, a preparation method thereof and an optical waveguide amplifier, and relates to the technical field of optical waveguides. An active overlying layer having a second refractive index, the first refractive index being greater than the second refractive index; wherein the active overlying layer comprises a substrate and a quantum dot structure uniformly mixed in the substrate, the quantum dot structure at least comprises a first size and a second size, and the first size is not equal to the second size. According to the optical waveguide doped with the quantum dot structures, higher luminous efficiency can be achieved through the quantum effect of the quantum dot structures, and the bandwidth and luminous efficiency of the waveguide amplifier can be improved through the quantum effect of the quantum dot structures of different sizes by doping at least two kinds of quantum dot structures of different sizes in the active upper covering layer.

A tunable microwave source based on dual-wavelength lasing of a single optical whispering gallery microcavity includes a dual-wavelength laser having the single optical whispering gallery microcavity for generating dual-wavelength lasing with adjustable spacing, narrow linewidth and low threshold; an optical fiber or waveguide amplifier for optical signal amplification; an optical filter for optical signal and noise filtration; and a high-speed detector for generating a tunable microwave signal with narrow bandwidth. The dual-wavelength laser includes a pump source, the optical whispering gallery microcavity, an optical waveguide or a tapered optical fiber, a microcavity substrate, and a gold electrode pair. The frequency spacing of the dual-wavelength lasing is tuned by adjusting the external voltage of the gold electrode pair.

The invention discloses a polymer waveguide amplifier capable of realizing L-band light amplification and improving C-band light amplification gain and a preparation method thereof, and belongs to the technical field of erbium-doped polymer optical waveguide amplifiers. Erbium is taken as one of matrixes, and meanwhile, the erbium and other elements are taken as matrixes together to prepare an alloy compound; the erbium element serving as the matrix is equivalent to increase the concentration of erbium in the compound, and the erbium element and other elements jointly serve as the matrix to form the alloy, so that the concentration quenching effect of erbium can be reduced; alloy compound particles are compounded in a polymer to prepare a gain medium of the polymer waveguide amplifier; preparing a polymer-based optical waveguide amplifier by taking the gain medium of the composite alloy compound particles as a core layer; according to the optical waveguide amplifier prepared through the method, the erbium ion concentration in the gain medium can be larger than or equal to 1018 cm <-3 >, high gain can be obtained in the L wave band and reaches 12 dB, light amplification of the polymer optical waveguide amplifier in the L wave band is achieved, and meanwhile the relative gain of the polymer optical waveguide amplifier in the C wave band can be improved.

Photonic integrated circuit waveguide amplifier fabrication method comprising providing at least one support cladding material or layer supporting at least one silicon nitride material or layer and / or at least one embedding cladding material or layer comprising the at least one silicon nitride material or layer embedded inside the at least one embedding cladding material or layer; wherein the at least one silicon nitride material or layer (has a material or layer thickness that is less than or equal to 400nm and greater than or equal to 40nm; and carrying out rare-earth ion implantation, at rare-earth ion acceleration values between 0.01 MeV and 0.5 MeV, by ion irradiation of at least one surface of the at least one supported and / or embedded silicon nitride material or layer, the at least one rare-earth ion implanted silicon nitride material or layer defining a waveguide core of the waveguide amplifier.

Laser amplifier system, including: a waveguide area (A) with a waveguide (10) for guiding laser radiation; an amplifier section (B) with an amplifier (20), wherein the amplifier section (B) is configured such that the laser radiation from a first end (A1) of the waveguide (10) is coupled into an input side (B1) of the amplifier (20); and an intermediate region (C) between the first end (A1) of the waveguide (10) and the input side (B1) of the amplifier (20), wherein the intermediate region (C) is configured to provide a variable thermal lens (30) for controllable adaptation of the laser radiation coupled into the amplifier (20); wherein the provision of the variable thermal lens (30) is effected by optical heating of the intermediate area (C) or the intermediate area (C) for the provision of the variable thermal lens (30) by electrical heating of the intermediate area (C) comprises an ohmic resistance element (32) applied to the intermediate area (C) as a means for local heating of the intermediate area (C).

An optical device comprises a Praseodymium (Pr)-dope waveguide optical amplifier capable of amplifying O-band light. The waveguide optical amplifier may be formed on the substrate (e.g., silicone or glass) and comprises a core defining an optical path through the waveguide optical amplifier, and cladding abutting at least one side of the core. The core comprises a silicon-based material, such as silicon nitride (Si3N4), doped with Praseodymium (Pr) such that, on condition of pump light and O-band signal light being passed through the waveguide optical amplifier, the waveguide optical amplifier amplifies the O-band signal light.

The invention discloses a polarization-independent erbium-doped optical waveguide amplifier device and a preparation method thereof, and relates to the technical field of amplifiers. The polarization-independent erbium-doped optical waveguide amplifier device comprises a substrate, a silicon oxide layer, an erbium-doped gain film layer, a passive transmission waveguide layer and a waveguide cladding which are sequentially connected from bottom to top, the passive transmission waveguide layer comprises a first single-mode transmission waveguide structure, a first waveguide mode converter for converting TM0 to TE1, a gain optical waveguide structure, a second waveguide mode converter for converting TE1 to TM0 and a second single-mode transmission waveguide structure which are connected in sequence in the horizontal direction; the gain optical waveguide structure comprises a first gain optical waveguide structure used for TE0 mode gain and a second gain optical waveguide structure used for TE1 mode gain, wherein the first gain optical waveguide structure and the second gain optical waveguide structure are connected in parallel. According to the amplifier device, the high-gain amplification effect of the TE0 mode and the TM0 mode is achieved, and meanwhile the gain difference of the two modes is reduced.

The present invention relates to a method for preparing a channel-type planar waveguide amplifier and a channel-type planar waveguide amplifier. The method for preparing the channel-type planar waveguide obtains an optical substrate with a developed channel structure by exposing and developing a photoresist spin-coated on the optical substrate using a photolithography mask plate with a preset channel structure, and then uses a plasma generated by an etching gas to etch a plurality of channels on the optical substrate according to the developed channel structure. Finally, a selected rare-earth-doped chalcogenide material is condensed on the optical substrate with etched channels by a melting-quenching method to form a chalcogenide thin film on the surface of the optical substrate; moreover, the selected rare-earth-doped chalcogenide material is condensed in the channels of the optical substrate by a melting-quenching method, which avoids etching the doped rare-earth material and ensures that the doped rare-earth material does not lose its activity during the condensation process, thereby obtaining the high-quality planar waveguide amplifier to be prepared.

The present invention provides a narrow-linewidth, high-power laser and a method for fabricating the same. The laser comprises: a substrate; a laser region formed on the substrate, flanked by amplifier regions and wavelength-stabilizing regions; a laser region ridge waveguide formed on the laser region; an amplifier region tapered waveguide formed on the amplifier region; a wavelength-stabilizing region ridge waveguide formed on the wavelength-stabilizing region; and electrical isolation trenches between the laser region, amplifier region, wavelength-stabilizing region, and the laser region ridge waveguide, amplifier region tapered waveguide, and wavelength-stabilizing region ridge waveguide. The present invention utilizes the tapered amplifier, wavelength stabilizer, and electrical isolation trenches between the functional regions to achieve high power, narrow linewidth, and stable wavelength control, providing a solution to existing problems with pump light sources.

The invention discloses a hybrid integrated optical comb amplifier based on silicon carbide and erbium-doped lithium niobate and a preparation method, and the preparation method comprises the steps: preparing a silicon carbide micro-ring optical frequency comb and an erbium-doped lithium niobate waveguide amplifier respectively, designing two device ports, and integrating the silicon carbide micro-ring optical frequency comb and the erbium-doped lithium niobate waveguide amplifier through end face coupling to obtain the hybrid integrated optical comb amplifier based on silicon carbide and erbium-doped lithium niobate. And thus, the hybrid integrated optical comb amplifier is obtained. The hybrid integrated optical comb amplifier disclosed by the invention has the characteristics of miniaturization, easiness in integration, random design of spatial shapes of the optical frequency comb part and the amplifier part, adjustable size and high degree of freedom, not only can improve the performance of an optical system in an application scene, but also can reduce the complexity and cost of the system. The method has a great application prospect in the high-tech fields of optical communication, laser radar, optical clocks, precise spectrum detection, quantum calculation and the like.

The invention discloses a heterogeneous integrated waveguide amplifier and an integration method. The waveguide amplifier comprises an end face coupler, a silicon-erbium-doped lithium niobate heterogeneous waveguide, a low-loss adiabatic conical coupler and an Euler bent waveguide. The silicon-based waveguide forms an end face coupler and an Euler bending waveguide; the silicon-erbium-doped lithium niobate heterogeneous waveguide forms an amplification waveguide and a low-loss adiabatic conical coupler. The integration method comprises the following steps: etching a silicon wafer to form a silicon-based waveguide; and the silicon-erbium-doped lithium niobate heterogeneous waveguide is formed by bonding an erbium-doped lithium niobate wafer. Erbium-doped lithium niobate is used as a gain medium to realize on-chip C-waveband signal light amplification; the waveguide amplifier is formed through the silicon-erbium-doped lithium niobate heterogeneous waveguide, etching of lithium niobate is avoided, and therefore the waveguide amplifier is compatible with the CMOS technology. Flexible heterogeneous integration between an active material and a passive material is realized through a bonding process from an erbium-doped lithium niobate wafer to a silicon wafer. By flexibly amplifying the on-chip signal light, the invention has important significance for realizing large-scale integration in the future.

The invention provides an optical waveguide amplifier based on a rare earth micron prism crystal and a preparation method, and relates to the technical field of optical waveguide amplifiers. The preparation method of the optical waveguide amplifier based on the rare earth micron prism crystal comprises the following steps: preparing the rare earth micron prism crystal with a flat end surface; preparing a SiO2 groove according to the size of the cross section of the rare earth micron prism crystal; determining the length of the SiO2 groove according to the number of the rare earth micron prism crystals to be arranged; a plurality of rare earth micron prism crystals are connected end to end in the axial direction and are linearly and tightly filled and arranged in the SiO2 groove to serve as a gain medium; and preparing the upper cladding. The rare earth micron prism crystals which are connected end to end are linearly and tightly arranged in the SiO2 groove in a filling mode to serve as the gain medium, lanthanide series rare earth light-emitting center ions can be evenly doped in the core layer of the waveguide gain medium, and preparation of the high-gain optical waveguide amplifier is achieved.

The present invention discloses a tunable microwave source based on a dual-wavelength laser of a single whispering gallery mode optical microcavity, comprising: a dual-wavelength laser based on a single whispering gallery mode optical microcavity, which is used to generate dual-wavelength lasing with adjustable spacing, narrow linewidth and low threshold; an optical fiber or optical waveguide amplifier, which is used to amplify optical signals; an optical filter, which is used to filter out other optical signals and noises; a high-speed detector, which is used to generate microwave signals with narrow bandwidth and tunability; wherein, the dual-wavelength laser based on a single whispering gallery mode optical microcavity includes: a pump light source, an optical waveguide or a tapered optical fiber, a substrate, a single whispering gallery mode optical microcavity and a pair of gold electrodes; the adjustable-spacing dual-wavelength lasing is realized by adjusting the magnitude of the applied voltage of the pair of gold electrodes. The present invention provides a realization scheme of a dual-wavelength laser with adjustable spacing, which has a simple structure. Based on the beat frequency of this laser, a tunable microwave source can be obtained.