12 results about "Photon density" patented technology

The invention relates to the technical field of optical fiber lasers, in particular to a miniaturized high-power narrow-linewidth optical fiber laser and a transmitting method.The laser comprises a single-frequency semiconductor laser, an optical fiber circulator, a first beam splitter, an optical fiber pre-amplifier, a second beam splitter, an optical fiber attenuator, an isolation band-pass filter and an optical fiber main amplifier; the first beam splitter is used for splitting the single-frequency laser, and the optical fiber pre-amplifier is used for performing power pre-amplification to obtain a pre-amplified optical signal; the second beam splitter is used for splitting the pre-amplified optical signal; the optical fiber attenuator is used for adjusting the carrier density and the photon density of the single-frequency semiconductor laser which are disturbed by the optical power fed back to the single-frequency semiconductor laser to induce a chaotic state, broadening the output spectrum of the semiconductor laser, and realizing effective suppression of stimulated Brillouin scattering in a power amplification process. According to the invention, a spectrum regulation and control mode with a simple structure is adopted, stimulated Brillouin scattering in a power amplification process can be inhibited, and high-power narrow-linewidth fiber laser output is realized.

The application relates to the technical field of semiconductor device special equipment manufacturing, and discloses a micro-order regulation method and system based on a metastable energy window. The method emits a pulse photon beam with a specific frequency to the surface of a semiconductor target material, so that lattice atoms enter a metastable energy window; the reflection spectrum of the semiconductor target material is collected in real time during the pulse intermittent period, and lattice vibration mode features are extracted; the lattice vibration mode features are compared with preset metastable energy window boundary threshold values, the photon density and the duration of the next pulse photon beam are dynamically adjusted according to the comparison result, and lattice atoms are repaired by short-range atomic rearrangement in the metastable energy window. The scheme limits energy injection to the metastable interval, and blocks the long-range diffusion path of doped atoms.

The invention discloses a distributed feedback laser based on an asymmetric sampling grating and a manufacturing method thereof, and belongs to the technical field of laser, in a grating structure of the laser, the position of equivalent pi phase shift deviates from the center of a cavity, and the duty ratio of the sampling grating, namely the ratio of the length of a sampling window to a sampling period, is less than 0.5. According to the invention, the reconstruction equivalent chirp technology is adopted, and the design of asymmetric phase shift and asymmetric coupling coefficient is combined, so that the forward output power is remarkably improved. In the structure of the laser, asymmetric regulation and control of photon density distribution are realized by optimizing the phase shift position and the duty ratio of the sampling grating, so that the forward output power is improved on the premise of keeping the stability of a single longitudinal mode. According to the method, the sampling structure is prepared by adopting a micron-sized photoetching technology, so that the dependence on high-precision electron beam photoetching is reduced, and the manufacturing tolerance and the cost effectiveness are improved. Experimental results show that the laser is stable in spectrum when working at the C wave band, and the side mode rejection ratio is higher than 50 dB.

The invention provides a directly modulated laser, which comprises a substrate, an epitaxial layer, a buffer layer, a grating layer, a lower limiting layer, an active layer, an upper limiting layer, a corrosion cut-off layer, a cladding and a contact layer, the structure of the grating layer is a convex grating structure with a lambda / 8 phase shift, the grating layer is located on the N-type doped side, and the convex grating structure with the lambda / 8 phase shift is used for reducing the photon density at the phase shift position through the negative reflector loss feedback effect and limiting hole gathering on the P-type doped side through the characteristic that the electron mobility is larger than the hole mobility.

The invention relates to the technical field of photoelectrons, and discloses a distributed feedback laser and a preparation method thereof, and the distributed feedback laser comprises a substrate layer, a separation limiting heterostructure, a coupling grating layer, a dielectric layer, an anode and a cathode. Bragg gratings are sectionally arranged on the side wall of the ridge waveguide of the coupling grating layer along the cavity length, each grating at least comprises two grating sections with different coupling coefficients, and a quarter-wavelength phase shift region is arranged at the center of the cavity; the end face of the cavity can adopt an anti-reflection or high-reflection coating film combination. The coupling coefficient and length ratio of each section is determined according to the end face reflectivity, target coupling coefficient distribution is achieved by changing parameters such as the side wall etching depth, the uniformity of photon density distributed along the cavity length is improved, the longitudinal space hole burning effect is restrained, and narrower line width is achieved while single longitudinal mode output is kept; the distributed feedback laser is simple in structural technological process, low in requirement for mask and etching precision and suitable for narrow-linewidth light sources with different cavity lengths and end face reflection conditions.

The application discloses a kind of external cavity VCSEL laser array mutual injection dynamics modeling simulation methods, comprising: setting up the structure parameters of external cavity VCSEL laser array with multiple high-order transverse mode and the working condition of driving external cavity VCSEL laser array normal operation;Based on L-K rate equation model, the dynamics model of external cavity VCSEL laser array mutual injection is established, and the partial differential equation set that carrier density, photon density and phase are related to space and time is constructed;The partial differential equation set is reduced, and the partial differential equation set is converted into only time variable ordinary differential equation set;The ordinary differential equation set is discretized, and numerical solution is calculated using finite difference method;The variation image of carrier density, photon density, phase and wavelength with time is output.The application can analyze the dynamics process of external cavity mutual injection of VCSEL array with multiple high-order transverse mode output, and find the condition that can realize coherent phase locking.

This invention provides a method for easily and accurately calculating the wet weight of seaweed. [Solution] The estimation method is a method for estimating the growth index of an object that grows in water by photosynthesis, comprising the steps of: measuring the photon density near the object during or after growth; and estimating the growth index of the object during or after growth based on the measured photon density and information showing the relationship between the photon density and the growth index.

Provided is a method for easily and highly accurately calculating the wet weight of seaweed. This estimation method is used for estimating a growth index of an object growing in water through photosynthesis, the method comprising: a step for measuring the photon density in the vicinity of the object during or after growth; and a step for estimating a growth index of the object during or after growth on the basis of the measured photon density and information indicating the relationship between the photon density and the growth index.

The application discloses a kind of dual-wavelength lasers, solve the technical problems that existing dual-wavelength lasers are unstable in power, or system is complex, bulky, or conversion efficiency is low, easily influenced by outside.This application uses semiconductor gain chip as gain medium, optical resonant cavity and optical filter as mode selector, realize controllable dual-wavelength laser output of frequency interval, adopt external cavity structure to obtain lower intracavity noise photon density;Optical resonant cavity used has very narrow filter bandwidth, can avoid mode competition problem, ensure the stable output of dual-wavelength laser;While generating dual-wavelength output, the four-wave mixing nonlinear effect in optical resonant cavity is utilized, and the phase noise and frequency stability of dual-wavelength beat signal are improved.

The application provides a P-SCH layer, a CW laser epitaxial structure and a preparation method thereof, and belongs to the field of semiconductors. The application provides a P-SCH layer, which is a multilayer structure, the number of layers of the multilayer structure is 2n, n is greater than or equal to 2, the emission wavelength increases from the first layer to the 2n layer; the difference between the emission wavelength of the n+1 layer and the emission wavelength of the n layer is 100-120 nm, and the difference between the emission wavelength of the remaining adjacent layers is 10-20 nm. The layer has a small span of two end emission wavelengths and a large span of middle emission wavelengths, a ladder structure, which greatly guarantees the electron leakage rate and the hole injection rate, thereby controlling the increase rate of the photon density with the increase of the current injection, and improving the device temperature stability.

Active hybrid silicon optical device structures including a silicon optical waveguide and a III-V semiconductor material stack further includes a high refractive index spacer located between the silicon waveguide and a III-V gain material. The spacer may be undoped or doped (e.g., n-type). The spacer may have a composition unique from the III-V semiconductor material stack or the spacer may have substantially the same composition as one or more other material layers of the III-V semiconductor stack. In exemplary embodiments, the spacer has a refractive index of at least 3.0 and a layer thickness of at least 0.3 μm. In laser structures, the spacer locates peak power of the resonant mode farther from the optical gain material and / or doped material having high optical loss. Along with reducing modal losses, mode area is increased, reducing photon density and improving laser reliability. In SOA structures, greater mode area may increase saturation power.