41results about How to "Large free spectral range" patented technology

The invention discloses a two-dimensional topological photonic crystal cavity, a design method thereof, and application in a laser. The two-dimensional topological photonic crystal cavity comprises aplurality of photonic crystal supercells that have a vortex-type structure change around the cavity center of the two-dimensional topological photonic crystal cavity, and the energy band of the plurality of photonic crystal supercells has a Dirac point at the equilibrium position where the vortex-type structure changes. The two-dimensional topological photonic crystal cavity, also known as a Diracvortex cavity, has the characteristics such as large mode field area, large free spectral range, narrow beam divergence angle, degeneracy of any mode and compatibility with a variety of substrate materials, and can be applied to surface emitting semiconductor lasers to ensure that the laser can still work stably in both single transverse mode and single longitudinal mode when outputting at largearea and high energy.

The invention relates to a polarization-irrelevant tunable Fabry-Perot filter which is characterized by comprising two liquid crystal boxes and a drive circuit; the two liquid crystal boxes respectively comprises a first optic transparent material, a liquid crystal material and a second optic transparent material which are installed sequentially; the second optic transparent material of the first liquid crystal box and the first optic transparent material of the second liquid crystal box are installed together; the optical axes of liquid crystal materials in the two liquid crystal boxes are vertical to each other and are arranged in a Fabry-Perot cavity; and the drive circuit is connected with the two liquid crystal boxes and a turning function of the filter is realized by controlling effective refractive indexes of the liquid crystal materials. The polarization-irrelevant tunable Fabry-Perot filter is reasonable in design, stable and reliable in performance, low in cost, small in size, easy for installation and production, and the like, has the turning characteristic irrelevant to a polarization state of incident light, does not have a mechanical moving part, and can be widely applied to the fields of lasers, optical test, optical fiber communication, organisms, medical equipment, optical fiber sensor networks, and the like.

An apparatus and method are disclosed for decreasing the spectral bandwidth of a semiconductor laser, such as a vertical cavity surface emitting laser.

The invention discloses a liquid crystal tunable wave filter and a configuration method thereof. The wave filter comprises a plurality of stages of cascaded Leo configuration wave filter units, and each Leo configuration wave filter unit consists of polarizing sheets of both sides and birefraction optical elements in the middle, wherein parts of or all of the Leo configuration wave filter units are merged through two continuous cascades or three continuous cascades for forming a merged unit, the merging mode is an overlapped type or fan type merging mode, and the birefraction optical elements are liquid crystal tunable wave plates or fixed wave plates or the combination of the liquid crystal tunable wave plates and the fixed wave plates. The liquid crystal tunable wave filter of the invention has the advantages of high passing rate, narrow full width at half maximum, high shielding rate, adjustable light spectrum range, high stability, no need of mechanical rotation, real-time controllability and the like, and can be widely applied to various fields such as imaging, biology, medicine, materials, optics, photonics, astronomy and the like.

The invention relates to the technical field of optical fiber sensing, in particular to a Fabry-Perot sensor based on a silicon core optical fiber and a preparation method thereof. The Fabry-Perot sensor based on the silicon core optical fiber comprises a common single mode optical fiber, an optical fiber fusion end face, the silicon core optical fiber and a polished end face, wherein an input optical fiber and the silicon core optical fiber are fused to form a fusion end face, the silicon core optical fiber consists of a silicon core optical fiber cladding and a silicon core optical fiber core, the polished end face is formed by grinding and polishing the end face of the silicon core optical fiber, and the fusion end face and the polished end face form two mirror faces of a silicon core optical fiber Fabry-Perot cavity. The Fabry-Perot sensor based on the silicon core optical fiber prepared by the invention has high temperature sensitivity, laser power sensitivity and response speed,and the Fabry-Perot sensor based on the silicon core optical fiber also has the advantages of simple structure, easiness in manufacturing, good repeatability and the like.

An etalon and a manufacturing method thereof relate to the optical field, in particular to the field of etalons. Ultra-thin film solid and hollow etalons are manufactured by binding plating with deepening optical cement and optical cement. After an optical medium with a certain thickness is directly plated on a reflecting film or a high reflecting film at the cavity part of the etalon, the solid etalon is formed by the optical cement and the deepening optical cement of another film layer in the cavity of the etalon or after a homogeneous dielectric film is placed in the non-central area of the film surface of the cavity of the etalon by adopting the shading or the photo etching method, the ultra-thin etalon with an air gap at the center is formed by the mutual optical cement and the deepening optical cement again. The invention discloses a novel etalon by adopting the technical proposal. The etalon has a small thickness, can achieve a plurality of um magnitudes, is bonded together by adopting the optical cement method and the deepening optical cement method, and can be manufactured more conveniently. Furthermore, the ultra-thin etalon has larger free spectral range and is suitable for laser mode selection and other aspects.

The invention relates to a single-mode continuous tunable optical filter which is mainly, technically characterized by comprising two transmission frequency Fabry-Perot tunable filters which are oppositely arranged back and forth, when the free spectral range of a first transmission frequency Fabry-Perot tunable filter is different from the intrinsic free spectral range of a second transmission frequency Fabry-Perot tunable filter at a certain interval, the transmission frequency tunable characteristic of the two transmission frequency Fabry-Perot tunable filters is utilized, so the tunable single-mode output is realized within a certain spectral range. The single-mode continuous tunable optical filter is reasonable in design, has the characteristics of no mechanical moving parts, stable and reliable performance, simple structure, low cost, small size, easiness for installation and production and the like, can meet the required small dimensions and reliable operation under extreme working environments, and can be widely applied in the fields of laser, optical test, optical fiber communication, biology, medical appliance, optical fiber sensor network and the like.

The invention belongs to the technical field of sensing, and provides an on-line dualbeam interference-type fiber refractive index sensor. The dualbeam interference-type fiber refractive index sensor comprises first single-mode fiber, light splitting fiber, offset-welded sensing single-mode fiber and reference single-mode fiber, light composition fiber and second single-mode fiber; while measuring, the sensing single-mode fiber is positioned in a to-be-checked substance; the wide spectrum light is input from the first single-mode fiber, then is coupled to the sensing single-mode fiber, and is subjected to propagation by a fiber core mode and a cladding mode and then mode transition, the fiber core mode is coupled to a cladding layer for continuous propagation, the partial energy of the cladding mode is coupled in the fiber core for continuous propagation, the light output by the reference single-mode fiber is subjected to light composition interference in the light composition fiber and is output through the second single-mode fiber, wavelength demodulation is carried out, and the refractive index change is obtained. Due to the light path compensation of the reference single-mode fiber, interference fringe drift distance is large, sensitivity is higher; the cooperation of the sensing single-mode fiber and the reference single-mode fiber have temperature compensating effect, so that the interference immunity and detection precision of the sensor are increased.

The invention discloses a transient high resolution spectrometer based on an F-P etalon, relating to the high resolution light spectrum measurement field and the transient light spectrometry field. The high resolution spectrometer disclosed by the invention realizes the high resolution detection of single-pulse transient spectrum through utilizing standard self-angle-light splitting and serial connection of multiple F-P etalons. The invention can be applied in the high resolution spectrum measurement field including the Brillouin scattering, the Zeeman effect, the spin electronics, etc.

The invention belongs to the technical field of terahertz sub-wavelength structure sensing, and provides a terahertz waveguide sensing device based on a Fano resonance coupling resonant cavity and a preparation method thereof. The terahertz waveguide sensing device based on the Fano resonance coupling resonant cavity comprises a substrate and a waveguide sensing unit, the waveguide sensing unit is arranged on the substrate and comprises a waveguide, a rectangular resonant cavity and a metal wall, and the rectangular resonant cavity is directly connected to one side of the waveguide in the direction perpendicular to the waveguide. The metal wall is arranged in the waveguide medium at a set distance on one side of the rectangular resonant cavity, and the center of the metal wall is provided with an aperture; and the direction of the rectangular resonant cavity is kept parallel to the polarization direction of the electric field, and the input end of the waveguide is used for receiving terahertz waves, so that Fano resonance is generated when the terahertz waves meet resonance conditions in the transmission process. By adopting a metal-medium-metal waveguide coupling resonant cavity structure, the refractive index sensing application with sharp Fano resonance, high Q factor and high sensitivity is realized.

The invention discloses an on-chip light source modulation system which comprises a silicon substrate, a silicon dioxide buried oxide layer and a silicon nitride layer, the silicon nitride layer comprises a first waveguide, a second waveguide, a third waveguide and a fourth waveguide which are sequentially arranged, a micro-ring resonant cavity is arranged between the first waveguide and the second waveguide, the distance between the micro-ring resonant cavity and the first waveguide is a first set distance, the distance between the micro-ring resonant cavity and the second waveguide is a second set distance; a micro-ring filter is arranged between the second waveguide and the third waveguide, the distance between the micro-ring filter and the second waveguide is a third set distance, and the distance between the micro-ring filter and the third waveguide is a fourth set distance; a micro-ring modulator is arranged between the third waveguide and the fourth waveguide, the distance between the micro-ring modulator and the third waveguide is a fifth set distance, and the distance between the micro-ring modulator and the fourth waveguide is a sixth set distance. According to the system, the three silicon nitride micro-ring structures are used for processing an input light source, and an optical frequency comb with a wider free spectral range can be generated.

The invention discloses an electrically tunable optical filter insensitive to the polarization state of incident light, which comprises a first Fabry-Perot interference cavity and a second Fabry-Perotinterference cavity which have the same principle and basic structure and are liquid crystal boxes driven by a power supply, wherein the first Fabry-Perot interference cavity comprises two spaced glass substrates, the two opposite surfaces of the two glass substrates are inner surfaces and are parallel to each other, the incident direction of light rays is perpendicular to the inner surfaces, andthe inner surfaces are sequentially plated with transparent electrodes, broadband high-reflectivity dielectric films and liquid crystal orientation films; the transparent electrodes on the glass substrates are respectively connected with two poles of an alternating-current voltage source through wires, first nematic phase liquid crystals with positive dielectric anisotropy are filled between theglass substrates, and the orientation direction of the first nematic phase liquid crystals is parallel to the inner surfaces of the two glass substrates. The invention has the advantages of large freespectrum range, small transmission spectrum full width at half maximum, large transmission wavelength adjustment range, small liquid crystal box thickness, short response time, simple structure and high reliability.

The invention discloses a single-longitudinal-mode narrow-linewidth optical fiber laser based on a double-coupling optical fiber ring and a Mach-Zehnder filter. The laser comprises a first optical isolator (1), a 980nm semiconductor laser (2), a 980/1,500nm wavelength division multiplexer (3), an erbium-doped fiber (4) with a concave cladding structure, an optical circulator (5), a non-pumped erbium-doped fiber (6), a fiber bragg grating (7), a passive resonant cavity (8) based on a double-coupling fiber loop and a Mach-Zehnder filter, a polarization beam splitter (9), a 1 * 2 optical coupler(10) and a second optical isolator (11), wherein the optical coupler (8) is composed of a first 2 * 2 optical coupler (12), a second 2 * 2 optical coupler (13) and a third 2 * 2 optical coupler (14).According to the passive resonant cavity based on the double-coupling optical fiber ring and the Mach-Zehnder filter, the two double-coupling optical fiber rings and the Mach-Zehnder filter are formed, the passive resonant cavity can serve as a narrow-band mode selection device to restrain multimode oscillation in the resonant cavity, and the non-pumped erbium-doped optical fiber serves as a saturable absorber; and the ultra-narrow band filtering effect can enable the annular cavity to realize stable single-frequency laser output. The laser has the advantages of narrow linewidth, low noise, high signal-to-noise ratio, simple structure and easiness in integration with an optical fiber system, and has huge potential in the fields of precision laser ranging, optical fiber communication, optical remote sensing and the like.

Aspects of the present disclosure are directed to photon-pair sources based on an external-cavity laser comprising a gain element and a planar-lightwave circuit that includes a surface-waveguide-based mirror and a ring resonator that enables four-wave mixing, where the surface-waveguide mirror and the ring resonator reside within the gain cavity of the laser itself. As a result, photon-pair sources in accordance with the present disclosure can have: (1) a larger free-spectral range for the entire laser cavity to enable generation of a single wavelength to realize single-mode operation without additional stabilization; and (2) low laser noise, thereby enabling detection and use of the generated photon pairs.