30results about How to "Improve optical conversion efficiency" patented technology

A vertical external cavity surface emitting laser (VECSEL) is provided in which a pump laser beam is incident on a laser chip at a right angle. In the surface emitting laser, a laser chip emits light at a first wavelength by optical pumping, an external mirror is spaced apart from the laser chip to reflect the first wavelength light emitted from the laser chip back to the laser chip, a pump laser emits light at a second wavelength to cause the laser chip to lase, a wavelength selecting mirror is disposed between the laser chip and the external mirror to reflect the second wavelength light emitted from pump laser to the laser chip and to transmit the first wavelength light emitted from the laser chip, and an optical unit is disposed between the wavelength selecting mirror and the laser chip to focus the first wavelength light on an optical path between the external mirror and the wavelength selecting mirror and to focus the second wavelength light on the laser chip.

The invention belongs to the technical field of a semiconductor nanometer material and application thereof, and relates to a core-shell structure quantum dot with a transition layer, a fabrication method and application of the core-shell structure quantum dot, a photoanode, a solar photo-electro-chemical device and application of the solar photo-electro-chemical device. The structure of the core-shell structure quantum dot with the transition layer comprises a core layer, the transition layer and a shell layer, wherein the transition layer is yCdSe<x>S<1-x>, the shell layer is CdS, x is more than 0 but less than 1, and y is more than 1. By changing the material structure of the quantum dot and adjusting the energy band structure of the quantum dot, the response of the quantum dot on sunlight is promoted, moreover, the separation of electron hole pairs is facilitated, and the photoelectronic generation efficiency is improved.

An Yb: YAG (yttrium aluminum garnet) and Cr, Yb: YAG self-Q-switching laser relates to a laser. The invention provides the Yb: YAG and Cr, Yb: YAG self-Q-switching laser with efficient and high-peak power laser output by bonding a Yb:YAG crystal and a Cr, Yb: YAG crystal. The Yb: YAG and Cr, Yb: YAG self-Q-switching laser is provided with a pump source, an isolator, a first lenticular lens, a second lenticular lens, the laser gain medium Yb:YAG crystal and the Cr, Yb:YAG crystal; the pump source, the isolator, the first lenticular lens, the second lenticular lens, the laser gain medium Yb:YAGcrystal and the Cr, Yb:YAG crystal are sequentially arrayed and positioned on the same optical axis from front to back, an anti-reflection film and a high-reflection film are plated on the rear surface of the laser gain medium Yb:YAG crystal and used as a rear cavity mirror of a laser cavity, and an anti-reflection film and a reflecting film are plated on the front surface of the Cr, Yb:YAG crystal and used as a front cavity mirror of the laser cavity.

The invention discloses a crystalline silicon solar cell antireflection film which is characterized by comprising a silicon oxynitride film, a titanium dioxide film, a silicon nitride film and a silicon dioxide film sequentially deposited on the surface of a silicon wafer. The refractive index of the four films gradually decreases from the silicon oxynitride film to the silicon dioxide film, and the thickness of the four films gradually increases from the silicon oxynitride film to the silicon dioxide film. The titanium dioxide film has high chemical stability to most chemical substances during production of cells and is high in refractive index and low in absorption rate, the silicon nitride film has good passivating effect on the silicon wafer, the silicon dioxide film has high damage threshold and excellent optical performance, and the silicon oxynitride film has excellent characteristics of silicon nitride and silicon oxide. Consequently, the crystalline silicon solar cell antireflection film can well improve optical conversion efficiency.

The invention discloses an adjustable high-optical-efficiency broadband multi-longitudinal-mode Raman microchip laser. The laser comprises a pumping source, a collimating lens, a focusing lens and a laser resonant cavity which are sequentially arranged along a light path, wherein the pumping source, the collimating lens, the focusing lens and the laser resonant cavity are located on the same horizontal optical axis and are vertically arranged; besides, after being collimated by the collimating lens, pump light emitted by the pumping source enters the focusing lens and is focused on the laser resonant cavity by the focusing lens, and after a pump light spot formed by focusing passes through the laser resonant cavity, broadband multi-longitudinal-mode laser with high optical efficiency is output. The laser is extremely short in cavity length, does not need special design, is simple in structure, is low in cost, facilitates miniaturization and integration of the laser, and is consistent with the development trend of an existing multi-wavelength laser; and according to the scheme, broadband multi-longitudinal-mode laser output can be obtained without inserting additional optical elements inside and outside the laser cavity, and the optical conversion efficiency of the output laser is high.

The invention discloses a dual-frequency terahertz wave parametric oscillator, comprising a KD*P crystal, a polarizer, a laser pumping module, a GaAs crystal, and a reflector and a paraboloid mirror arranged around the GaAs crystal. A pump source is provided by a first mirror, second mirror, third mirror, Fourth mirror, fifth mirror, a sixth mirror, a seventh mirror, an eighth mirror, a KD*P crystal, a polarizer, and a laser pumping module. The pumping light emitted from the pumping source is resonantly amplified in a resonant cavity composed of a first mirror, a second mirror, a third mirror,a fourth mirror, a fifth mirror, a sixth mirror, a seventh mirror, and an eighth mirror. In the process of optical parameters, Stokes light and pump light in the cavity can be recycled, and the efficiency of pump light can be improved effectively. Four THz waves are emitted perpendicular to GaAs crystal, and no coupling device is needed to reduce the loss of THz wave.

The invention discloses a three-dimensional terahertz wave parametric oscillator, comprising a pump source, a GaAs crystal, a mirror and a paraboloid mirror arranged around the GaAs crystal; The pumpsource is made up of KD*P crystal, Polarizer, Nd: A YAG laser pumping module is composed of a first mirror, a second mirror, a third mirror, a fourth mirror, a fifth mirror and a sixth mirror. The pumping light emitted from the pumping source is resonantly amplified in a resonant cavity composed of a first mirror, a second mirror, a third mirror, a fourth mirror, a fifth mirror and a sixth mirror.In the process of optical parameters, Stokes light and pump light in the cavity can be recycled, and the efficiency of pump light can be improved effectively. Six terahertz waves can be generated byone pump beam, and the optical conversion efficiency is effectively increased.

The invention provides a device for generating an optical comb based on optimized difference frequency. First pump light emitted from a first pump source enters a beam combiner; second pump light emitted from a second pump source enters the beam combiner through a phase delay system; the first pump light and the second pump light are mixed into frequency-mixed light in the beam combiner; the frequency-mixed light passes through a telescope system and then enters an APPLN crystal; the frequency-mixed light generates cascaded light in the APPLN crystal under the action of cascaded optical difference frequency; and the cascaded light enters a GaP waveguide and generates the optical comb through the effect of optimizing cascade optical difference frequency. By arranging the APPLN crystal, the cascaded light is transferred to a Stokes region, and the frequency range of the generated optical comb is wide. By enhancing the Stokes cascade difference frequency and inhibiting the anti-Stokes cascade difference frequency at the same time, the optical conversion efficiency is improved.

The invention provides a multi-frequency terahertz wave generation device based on optimized cascade difference frequency. Mixed frequency light enters a PPLN crystal, cascade light of all stages is generated through the cascade optical difference frequency effect, the cascade light of all stages passes through a sixth reflecting mirror and a seventh reflecting mirror and then enters a fan-shaped structure PPLN crystal, an included angle theta is formed between the cascade light entering the fan-shaped structure PPLN crystal and the positive direction of the X axis; terahertz waves are generated by the cascade light in the fan-shaped structure PPLN crystal through the cascade optical difference frequency effect; the terahertz waves of multiple frequencies can be obtained by changing the incident position and the incident angle of the cascade light in the fan-shaped structure PPLN crystal; the terahertz waves are coupled out through a parabolic mirror to change the incident position and the incident angle theta of the cascade light, the terahertz waves with different frequencies can be obtained, the tuning mode is simple, and operation is flexible. By changing the polarization period distribution of the an-shaped structure PPLN crystal, the Stokes cascade difference frequency can be enhanced, meanwhile, the anti-Stokes cascade difference frequency is inhibited, and the terahertz wave optical conversion efficiency is improved.

The invention discloses a nested coupling terahertz wave parameter oscillator. The nested coupling terahertz wave parameter oscillator comprises a KD*P crystal, a polarization plate, a Nd: YAG laser pumping module, a GaAs crystal and reflectors arranged around the GaAs crystal; the pumping source is composed of the KD*P crystal, the polarization plate, the Nd: YAG laser pumping module and a firstreflector, a second reflector, a third reflector, a fourth reflector and a fifth reflector; and the pumping light emitted by the pumping source is resonated and amplified in a resonant cavity definedby the first reflector, the second reflector, the third reflector, the third reflector and the fifth reflector. In the optical parameter process, the Stokes light and the pump light in the cavity canbe recycled, so that the pump light utilization efficiency is effectively improved; and four beams of THz waves are perpendicular to the GaAs crystal to emit, so that no coupling output device is needed, and terahertz wave output loss is effectively reduced.

The invention discloses a quasi-phase matching terahertz wave parametric oscillator, including a pumping source, a first period inverted GaP crystal, a second period inverted GaP crystal, a third period inverted GaP crystal, a fourth period inverted GaP crystaln, and reflectors arranged around the first period inverted GaP crystal, a second period inverted GaP crystal, a third period inverted GaPcrystal, a fourth period inverted GaP crystal; the reflector comprising a first mirror, a second mirror, a third mirror, a fourth mirror, a fifth mirror, a sixth mirror, a seventh mirror, an eighth mirror, a ninth mirror, and a tenth mirror. The generated Stokes light oscillates back and forth in the ring resonator, and the THz wave can be amplified effectively by the optical parametric effect. The collinear interaction between pump light and Stokes light increases the interaction volume between pump light, Stokes light and THz wave.