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125 results about "Mode hopping" patented technology

Mode hopping occurs for specific values of laser case temperature and injection current. This means that mode hopping can be eliminated by carefully controlling these two parameters. Mode hopping can be caused by other external influences.

Wavelength discretely tunable semiconductor laser

A wavelength discretely tunable semiconductor laser that addresses wide wavelength tuning range, is mode hopping free, has high output power, has fast wavelength switching time, is wavelength locking free and is relatively simple. Four exemplary embodiments disclosed herein utilize a wavelength discretely tunable semiconductor laser that comprises a discretely tunable filter and laser amplifier. In the first embodiment, the tuning element comprises a pair of cascade Fabry-Perot filters, each having a plurality of characteristic narrow transmission passbands that pass only the cavity mode under the passband. The spacing between the narrow transmission passbands are slightly different in one filter from the other filter so that only one passband from each filter can be overlapped in any given condition over the entire active element gain spectral range, thereby permitting lasing only at a single cavity mode passed by the cascade double filters. One of the two etalon filters can be made with a plurality of transmission passbands predetermined by industry, application and international standards, making this element an intra-cavity wavelength reference and eliminating further wavelength locking needs for the tunable laser. In a second embodiment, one of the two etalons is replaced by a wedge filter. The filter optical path change and thus the transmission passband shift are achieved by translating the wedge filter in a direction perpendicular to the optical axis. In a third embodiment, one of the two etalon filters is replaced by a polarization interference filter. The polarization interference filter consists of an electro-optically-tunable birefringent waveplate, a fixed birefringent waveplate, the laser cavity and T.E. polarization light emitted from the laser diode. In a fourth embodiment, the laser and wavelength tuning structure are integrated on a semiconductor substrate by epitaxy processes.
Owner:JIN HONG

Fiber bragg grating temperature/strain sensing system and demodulation method thereof

The invention relates to a fiber bragg grating temperature/strain sensing system and a demodulation method thereof. The method comprises the following steps: after seed layer generated by a narrow linewidth laser light source module generates a sideband through a phase modulation module, injecting into active fiber grating stimulated by pump light through a circulator and a wavelength division multiplexer in an active fiber grating module; and performing photovoltaic conversion on return light and a photoelectric detector connected with the circulator to acquire a beat frequency signal, extracting a component, namely an error signal reflecting the center frequency deviation between the narrow linewidth laser and the active fiber grating, at the phase modulation frequency position by a phase-locked amplifier, and generating a feedback voltage signal by a feedback control module by virtue of the error signal to control the center frequency of the narrow linewidth laser so as to realize injection locking between the narrow linewidth laser and the active fiber grating. The quasi-static accuracy of p-epsilon can be achieved; the characteristic of adjustable strain sensitivity is achieved; and the problems of mode jump, relaxation shock and low-frequency phase noise in a fiber laser sensor can be effectively solved.
Owner:宁波联河光子技术有限公司

Littrow-structure tunable external-cavity laser and mode-hopping-free sweep-frequency regulation method thereof

ActiveCN103151703AOptical cavity length compensationAchieve mode-hop-free tuningLaser optical resonator constructionLaser output parameters controlGratingExternal cavity laser
The invention relates to a Littrow-structure tunable external-cavity laser and a mode-hopping-free sweep-frequency regulation method thereof, belonging to the technical field of laser tuning. The problem that the existing Littrow-structure external-cavity laser cannot realize large-scale mode-hopping-free tuning is solved. The Littrow-structure tunable external-cavity laser comprises a semiconductor laser, a liquid crystal spatial light modulator and a blazed grating. The mode-hopping-free sweep-frequency regulation method comprises the steps that laser beams which are emitted by the semiconductor laser are enabled to pass through the liquid crystal spatial light modulator and then to be incident onto the blazed grating, first-order diffracted light which passes through the blazed grating and returns back along the original path forms resonance between the inner cavity and the outer cavity of the tunable external-cavity laser, and finally the light emerges from the zero order of the blazed grating; and the blazed grating is rotated around an axis point O, the voltage of the liquid crystal spatial light modulator is changed at the same time to change the refractive index of the liquid crystal spatial light modulator and the mode-hopping-free sweep-frequency regulation of the tunable external-cavity laser is realized during tuning by rotating the blazed grating. The mode-hopping-free sweep-frequency regulation method is applicable to the regulation of lasers.
Owner:HARBIN INST OF TECH

Manufacturing method of multi-color and multi-functional EVA sports and leisure sole

The invention relates to the technical fields of shoes and particularly relates to a manufacturing method of a multi-color and multi-functional EVA sports and leisure sole. The method comprises the following steps of manufacturing first EVA particles and second EVA particles according to the formula separately; injecting the two EVA particles into a mold corresponding to an injection device for prefabricating and molding; cooling and opening the mold so as to obtain a pre-foamed sole base of a sole main body and a pre-foamed sole base of a functional part separately; putting the two sole bases into different positions in a foaming mold separately, and carrying out foam molding to obtain a crude foamed sole product; and carrying out mode hopping on the crude foamed sole product and then carrying out gradient cooling, setting by cooling and trimming to obtain the multi-color and multi-functional EVA sports and leisure sole. The manufacturing method is simple in process, low in production cost, high in production efficiency and low in defect rate; the prepared multi-color and multi-functional EVA sports and leisure sole has the advantages of being light, good in damping property, good in elasticity, good in wear resistance and good in slip resistance, and is convenient to wear; and the functional part does not easily fall off from the sole main body.
Owner:GUANGDONG GUOLI SCI & TECH CO LTD

Tunable semiconductor laser with Littman-structured outer cavity

InactiveCN105932541AGuaranteed stretching in a straight lineNo assembly errorsLaser detailsLaser optical resonator constructionArchitectural engineeringFrequency modulation
The invention discloses a tunable semiconductor laser with a Littman-structured outer cavity. The tunable semiconductor laser comprises a base, a supporting base, an optical path adjustment accessory, a raster base, a reflecting mirror base, a sleeve base, a one-dimensional flexible platform and a flexible hinge, wherein the supporting base is fixed on the horizontally-arranged base; the supporting base comprises a bottom plate and a supporting table, wherein the cantilever of the supporting table is arranged on the bottom plate; the optical path adjustment accessory, the raster base and the flexible hinge are fixed on the bottom plate; a vertical mounting plane is arranged on the supporting table; the one-dimensional flexible platform is mounted on the vertical mounting plane; the one-dimensional flexible platform is provided with a mounting part used for mounting the sleeve base; the sleeve base is mounted on the mounting part through a semiconductor cooler; the flexible hinge is hinged with the cantilever; a PZT used for pushing the cantilever to swing around the hinge is also mounted on the flexible hinge; the reflecting mirror base is fixed at the tail end of the cantilever; and a reflecting mirror mounting part is arranged at the upper part of the reflecting mirror base in a cantilever-shaped manner. The tunable semiconductor laser with the Littman-structured outer cavity can realize large-range frequency modulation without mode hopping.
Owner:XI AN JIAOTONG UNIV
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