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.

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.

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.