40results about How to "High side mode suppression ratio" patented technology

The invention discloses a topological bulk laser based on an energy band inversion light field limiting effect and a method, being characterized in that a topological state photonic crystal which generates a dipole mode and a quadrupole mode near the center of a Brillouin zone and generates energy band reversing and a topological moderate state photonic crystal which does not generate energy bandreversing are adopted; the spliced boundary can generate reflection and limitation effects of a light field, and the boundary encircles to form a closed curve, so that a laser resonant cavity is formed in the boundary. According to the topological bulk laser based on an energy band inversion light field limiting effect and the method, single-mode vertical laser emission with high directivity, lowthreshold, narrow linewidth and high side-mode rejection ratio can be realized; the process difficulty and the preparation cost are reduced; the problems of heat dissipation and electric injection areimproved; the stability of components is improved, and the service life is prolonged; after copying to an electric injection active material system, the topological bulk laser based on an energy bandinversion light field limiting effect can obtain the vertical emitting laser with controllable size, high directivity, low threshold, narrow linewidth and high side mode rejection ratio; and the topological bulk laser based on an energy band inversion light field limiting effect can be applied to the fields of optical communication, solid-state lighting, laser radar, substance detection, medicaldiagnosis and the like.

A DFB semiconductor laser device including: a semiconductor substrate; and an active layer and a diffraction grating overlying the semiconductor substrate, the diffraction grating having a composition of GaInNAs(Sb) and absorbing light having a laser emission wavelength of the active layer. The DFB semiconductor laser device having a higher SMSR can be provided which stably operates in a wider range of injection current by proving the diffraction grating formed by the GaInNAs(Sb) having the composition for efficiently absorbing light which has the laser emission wavelength of the active layer.

The invention discloses a V-type coupling cavity wavelength switchable semiconductor laser, comprising two optical resonant cavities, each comprising a segment of light waveguide and partial reflecting elements at the two ends; the two segments of light waveguides are arranged on a chip to form a V shape, there is no coupling at the opening end but there is a certain cross coupling at the closed end to make the laser have optimum single-mode selectivity; the first optical resonant cavity has a fixed optical length to make its resonant frequency be on a series of independent equidistant channels; the second optical resonant cavity has a certain length difference from the first one, and by changing effective refractivity of partial waveguides in the second optical resonant cavity, it can make the laser wavelengths mutually switched on a series of channels determined by the first optical resonant cavity. And the laser can further comprise one or two branch couplers or directional couplers added outside the cavity to improve coupling efficiency of external devices, and providing added modulating or space switching functions.

The invention discloses a mixed silicon single mode annular cavity laser based on microstructural silicon waveguide frequency selection, comprising a silicon substrate, a silicon dioxide layer formed on the silicon substrate, a silicon annular waveguide layer formed on the silicon dioxide layer, a bonding buffer layer formed on the silicon waveguide layer, an N type contact layer formed on the bonding buffer layer, an N type electrode formed in the middle on the N type contact layer, an annular quantum well active region formed in an annular part of the N type electrode on the N type contact layer, a P type annular contact layer formed on the annular quantum well active region, a P type annular cover layer formed on the P type annular contact layer and a P type electrode formed on the P type annular cover layer. The structure is in high density integration, single longitudinal mode working and high-efficiency coupling outputting; and more importantly, according to the mixed silicon single mode annular cavity laser disclosed by the invention, technological steps of conventional DFB distributed feedback grating manufacturing, III-V group material secondary epitaxy and the like are saved in technological processing, and the complexity is lowered.

The invention discloses a distribution feedback external cavity narrow line board semi-conductor laser for achieving frequency self-locking, which comprises a semi-conductor laser (a), a collimating lens (b), a polarizingprism (c), a first 1 / 4 wave plate (d), an F-P etalon (e), a second 1 / 4 wave plate (f), a front cavity reflector (g), an isolator (h), a focusing lens (f), and an optical fiber (j). The laser disclosed by the invention can effectively narrow the light width of a light source, and achieve the frequency self-locking of the external cavity semi-conductor laser.

The invention provides a wavelength division-time division hybrid passive optical network system, which comprises a central office, a plurality of optical network units and a remote node, wherein the remote node is positioned between the central office and the plurality of optical network units; the central office is provided with a plurality of light sources for emitting downlink signal light of various wavelengths, a plurality of receivers for receiving uplink signal light emitted by the plurality of optical network units and transmitted by the remote node respectively, and a plurality of multiplexer / demultiplexers for multiplexing and demultiplexing the downlink signal light and the uplink signal light; the remote end node is used for multiplexing the downlink signal light from the central office and demultiplexing the uplink signal light from the optical network units; and each optical network unit is provided with an internal annular coupler, a light separating unit for separating downlink signal light into signal light and injection light, a downlink data receiver for receiving separated signal light, and an MEMS (Micro Electro Mechanical System) tunable laser for receiving injection light and generating uplink signal light.

This invention relates to a waveguide and a grating structure of an adjustable distribution feed back quanta cascade laser obtaining low threshold value current density and high side mode suppression ratio and a method for preparing first order grating of laser meeting the requirement, in which, the laser waveguide and the grating structure is a limit structure in the waveguide made up of a deep first order grating and a thin heavy doped semiconductor layer, said grating corrosion technology is to utilize the InGaAs / InP structure as the corrosion sacrificial layer of the grating and select different corroding liquid matches to get a grating structure with the depth adjustable and accuracy controllable.

The invention provides a wrinkle type apodization waveguide Bragg grating filter, comprising a substrate, a lower cladding layer, an upper cladding layer, a straight waveguide and a lower grating. The width of the lower grating is gradually increased according to a bell-shaped envelope function; the width of a grating wire located at an end part is less than the width of the straight waveguide; and the width of the grating wire located at a middle part is more than the width of the straight waveguide. The invention further provides a manufacturing method of the filter, comprising the following steps of: coating the lower cladding layer on the substrate; manufacturing an anti-etching layer; spinning negative photoresist; carrying out mask exposure; generating a structure of the lower grating through interference; developing and corroding an area of the lower grating; etching the lower grating; removing the residual negative photoresist and corroding; spinning a coating core layer material; evaporating an aluminum layer; etching the straight waveguide; developing an area outside the straight waveguide, and manufacturing the straight waveguide through corrosion; rotatably coating the upper cladding layer, and curing and drying in a vacuum manner. The filter has apodization effects with high reflectivity and high side-mode suppression ratio.

A method for generating a single-frequency oscillating microwave signal and a single-frequency oscillating microwave signal source, based on the following technical idea: applying the principle of stimulated Brillouin scattering and constructing an intensity modulation subsystem based on an electro-optic phase modulator to replace the electro-optic intensity modulation in an optoelectronic oscillator and use the intensity modulation subsystem to realize the electro-optic intensity modulation function; stimulate the Brillouin scattering by exciting the nonlinearity of the highly linear optical fiber in the intensity modulation subsystem, and the scattered light is transmitted back and interferes with the optical carrier to form a microwave signal. Based on the vernier caliper effect, the oscillation mode consistent with the frequency of the microwave signal is locked into the main mode, and based on the mode competition mechanism, the side mode originating from the white noise of the system is suppressed for the first time; at the same time, in the cycle process, the main mode The oscillating signal is amplified through the gain region of Brillouin scattering, while the side-mode oscillating signal is suppressed again through the loss region and the intrinsic loss region. After double suppression, a single-frequency oscillating microwave signal with a high side-mode suppression ratio is generated.

The invention provides an ultra-narrow line width laser device. The laser device comprises a laser-generating gain device, an optical coupler, and two feedback compression devices, wherein the laser-generating gain device is connected to the one end of the optical coupler, and the other end of the optical coupler is connected with output optical fibers and the feedback compression devices. By designing cavity lengths and a cavity length difference value of the feedback compression devices, single longitudinal mode narrow line-width laser output is obtained, and a side-mode suppression ratio of output lasers is improved; generated lasers of preset quantity are transmitted to the optical coupler by the laser-generating gain device, and the lasers are transmitted to the corresponding feedback compression devices by the optical coupler; each feedback compression device narrows incident layer line width, and the narrowed laser line width is transmitted back to the laser-generating gain device by the optical coupler to be subjected to gain amplification; after gain amplification, the lasers go through the optical coupler and is transmitted to the feedback compression devices to circularly narrow the laser line width till the lasers of preset quantity are all transmitted out through the output optical fibers.