850 results about "Longitudinal mode" patented technology

A process for operation of a laser device (1) is described, whereby circulating light pulses each comprising spectral components according to a plurality of longitudinal modes of a resonator configuration (3) are generated in the resonator configuration (3) and subjected to a compensation of group velocity dispersion, and a predetermined linear dispersion is introduced into the light path of the resonator configuration (3), so that at least one mode has a predetermined frequency and/or the mode distance between the modes has a predetermined value. Furthermore, regulations for stabilizing the laser device on the basis of this process and applications of the regulations for the generation for stabilized, ultra-short light pulses, generation of optical frequencies and in the frequency and/or time measuring technique as well as in the spectroscopy are described.

A low-noise laser diode module comprises a laser diode for emitting light with a wavelength in the range from UV to IR, a drive circuit for injecting electrical current into said diode, and an automatic power control circuit for monitoring and adjusting laser output power using front-facet photodiode external to the laser assembly and a feedback loop. Said drive circuit produces injection current modulated by an RF signal with variable degrees, depending on the wavelength to be stabilized, the desired spectral bandwidths of the laser output, and/or other applications. Said RF signal can be a sine wave, a distorted sine wave, a rectified sine wave, a non-sine wave, a series of narrow pulses, or repetitive shunt. The present invention encompasses a method for producing stable, broadband, and low-coherent laser. The present invention also encompasses a method for producing stable narrowband or single longitudinal mode laser. The present invention further encompasses a compact light source applicable to DPSS lasers, fiber lasers, optical parametric oscillators, low-speckle laser display systems, and seeders, with or without nonlinear frequency conversion processes.

Either one of a transmission terminal connected to a transmission filter and a receiving terminal connected to a receiving filter is a balanced type terminal, and the other is an unbalanced type terminal. The transmission filter and the receiving filter includes surface acoustic wave resonators or film bulk acoustic resonators. The balanced type terminal is connected to a longitudinal mode coupled surface acoustic wave filter.

A system which improves wavelength tolerance, compensates dispersion in a simple way, reduces limitation of the fiber input power is disclosed. The operation includes receiving a clock signal from a system clock source; modulating a single mode optical signal based on the clock signal and generating an optical pulse signal having two longitudinal modes, the frequency interval thereof being n×B, n being a natural number and B being a transmission speed; generating a partial response signal by converting a binary NRZ signal from a digital signal source in synchronism with the system clock source; and modulating the optical pulse signal based on the partial response signal, and outputting a binary RZ modulated signal. The binary RZ modulated signal is input into a receiver, where two partial response components in the optical spectra of the input signal are divided, and one or both of the components are received.

A system for reducing reflection of an optical system can reduce or eliminate reflection at facets of a semiconductor gain medium and can suppress natural longitudinal modes produced within the semiconductor gain medium. In combination with external feedback, the system can allow more precise wavelength control of the light output of a laser, thereby allowing the laser to be used in a dense wavelength division multiplexing system. The system employs a patterned relief surface disposed on a facet of a gain medium. The patterned relief surface may be a "motheye" pattern having a plurality of conical posts disposed on the surface of the facet. The system may be combined with conventional devices, such as a Bragg reflector or a microelectromechanical component, to further improve wavelength control of a resonant optical cavity, thereby improving the operation of optical communications systems.

A method and system for use in an ocular surgical procedure is provided. The design includes a handpiece having an ultrasonically vibrating tip operational within a plurality of operating modes including a first operating mode and a sensing device, such as a vacuum pressure sensor. A controller is connected to the handpiece and sensing device and is configured to receive data from the sensing device and adjust at least one operational parameter (time/duty cycle of operation, power during operation) associated with the first operating mode and adjust at least one parameter associated with another operating mode based on the data received from the sensing device. Operational modes may include multiple longitudinal or non-longitudinal modes (torsional, transversal, etc.) or combinations of longitudinal and/or non-longitudinal modes.

A double-longitudinal-mode laser heat frequency stabilization method and a device based on the iodine frequency stabilization reference light belong to the application technical field, the invention takes the center frequency of the iodine frequency stabilization laser with a relative frequency accuracy being 10<-11> as a reference frequency, and leads the frequency of laser output by multi-double-longitudinal-mode lasers to keep one fixed difference with the reference frequency through regulating cavity length, so that the relative frequency accuracy of the double-longitudinal-mode laser is improved from 10<-7>-10<-8> to 10<-9>, the frequency consistency of multi-double-longitudinal-mode lasers is improved from 10<-7> to 10<-9>, therefore, the problems that the relative frequency accuracy of the double-longitudinal-mode laser can not exceed 10<-8> and the frequency consistency of multi-double-longitudinal-mode lasers is poor are solved.

The invention discloses a multi-frequency synchronization phase laser ranging device and a method based on dual-acousto-optic shift frequency, relates to the technical field of laser ranging, and mainly relates to a phase laser ranging technology, solving the problem that a device and a method which can achieve both of the synchronism and stability of multiple measuring tapes are in lack in the existing phase laser ranging technology. The multi-frequency synchronization phase laser ranging device based on dual-acousto-optic shift frequency comprises a dual-longitudinal-mode stable frequency He-Ne laser, a multi-measuring-tape generating unit, a bundle expanding and collimating lens set, a light path and circuit measuring unit and a control box unit. The multi-frequency synchronization phase laser ranging method based on dual-acousto-optic comprises the following concrete steps: step one, switching on the dual-longitudinal-mode stable frequency He-Ne laser; step two, taking one beam oflaser as a reference laser beam, and taking the other beam of laser as a measurement laser; step three, taking (f'+f2)-(f+f1) as the accurate measurement tape frequency, and taking a low-frequency electric signal f1-f2 as the rough measurement tape frequency; and step four, moving a measuring cone prism to the target end. The device and the method are used for phase laser ranging.

An injection locked transmitter for an optical communication network includes a master seed laser source input substantially confined to a single longitudinal mode, an input data stream, and a laser injected modulator including at least one slave laser having a resonator frequency that is injection locked to a frequency of the single longitudinal mode of the master seed laser source. The laser injected modulator is configured to receive the master seed laser source input and the input data stream, and output a laser modulated data stream.

A laser light source is provided with a pump light source (1) comprising a semiconductor laser, a solid laser medium (2) which is excited by the semiconductor laser, and multi-mode means for changing at least either a longitudinal mode or a transverse mode of laser oscillation of the solid laser. The oscillation light of the laser medium excited by the light outputted from the pump light source is changed by the multi-mode means into output light (5) having a plurality of oscillation spectra and is outputted, thereby a small, high power, and highly efficient low coherent light source can be realized, and a laser light source having reduced speckle noises can be provided.

Systems, devices and methods of generating both a precision electrical timing signal as well as a precision optical timing signal. A novel, modified opto-electronic loop oscillator is used to drive a harmonic mode-locked laser. A novel opto-electronic loop has a larger “Q” factor by increasing the electrical loop oscillating frequency ω₀ by using a beat note created by the selection of two optical longitudinal modes from the mode-locked laser. The beat note is detected and divided down to drive a modulator that mode-locks the laser. The frequency division stage also reduces the noise.

A method for effective injection seeding is based on continuous wavelength sweeping for matching the injected seeds with one or more longitudinal mode(s) of the slave oscillator in every pulse. This is achieved through rapidly varying laser drive current, as a result of RF modulation. Depending on the modulation parameters, the seeder may be operated in CW or quasi-CW or pulsed mode, with a narrow or broad bandwidth, for injection seeding of single longitudinal mode or multimode. The wavelength and bandwidth of the laser output can be tuned according to the needs. Injection seeding of high repetition rates is achievable. From pulse to pulse, the master-slave resonance persists though may occur at different longitudinal modes upon cavity length fluctuations. Cavity length control and phase locking schemes are consequently not required. The present invention also encompasses an injection seeding laser system, which is constructed in accordance with the inventive method, and a novel application of RF modulated laser diode to spectrum/wavelength control and to producing high power Gaussian beam with narrow pulse width in a stable, reliable, and cost-effective manner.

A double-longitudinal-mode laser frequency-offset-lock method and a device based on cavity length thermal regulation belong to the application technical field; the invention takes the frequency of laser output by a power balanced type double-longitudinal-mode frequency stabilization laser A as a reference frequency, and simultaneously leads the frequency of laser output by the double-longitudinal-mode laser A with n being more than or equal to B1, B2,..., Bn to keep one fixed difference with the reference frequency, thus ensuring that the laser output by the double-longitudinal-mode laser B1, B2,..., Bn has uniform frequency value, the frequency stability and frequency consistency of the double-longitudinal-mode laser can reach 10<-8>, thereby overcoming the shortcoming that the frequency consistency between frequency stabilization lasers only reaches 10<-6>-10<-7> in the traditional frequency stabilization lasers.

The invention relates to a high-precision multi-frequency phase-synchronized laser distance measurement device and method, relates to the technical filed of laser measurement, and mainly relates to a phase laser distance measurement technology. In the invention, the problem that a device and a method capable of realizing both synchronization and stability of multiple measurement gauges are in shortage in the phase laser distance measurement technology is solved. The high-precision multi-frequency phase-synchronized laser distance measurement device comprises a dual-longitudinal-mode frequencystabilization He-Ne laser, a multi measurement gauge generation unit, a beam expanding collimating mirror group, a measuring light path and circuit unit and a control casing unit. The high-precision multi-frequency phase-synchronized laser distance measurement method specifically comprises the following steps of: 1, starting the dual-longitudinal-mode frequency stabilization He-Ne laser; 2, taking one beam of laser as a reference laser beam and the other beam as a measurement laser beam; 3, taking [(f'+f2)-(f+f1)] as the frequency of an accurate measurement gauge and taking (f1-f2) as the frequency of a coarse measurement gauge; 4, moving a measurement corner-cube prism to a target end; 5, obtaining a phase difference phi p; 6, obtaining a phase difference phi c; and 7, obtaining the distance. Thus, the method and device disclosed by the invention can be used for laser distance measurement.

A laser apparatus for nonlinear conversion of light is disclosed utilizing a laser diode having a reflective back facet and a front facet having a reflectance of less than about 1% for emitting a multifrequency optical beam, and a nonlinear optical element for receiving the multifrequency optical beam and for generating a frequency-converted radiation. An external frequency-selective reflector is provided for power and spectral stabilization of the multifrequency optical beam, and for confining its optical spectrum within a bandwidth of efficient nonlinear conversion in the nonlinear optical element. The laser diode reflective back facet and the external frequency-selective reflector form an extended laser cavity. In operation, the multifrequency optical beam contains a plurality of longitudinal modes of the extended laser cavity which are confined within the frequency conversion bandwidth of the nonlinear element. The external frequency-selective reflector may comprise a waveguiding element such as a single-mode fiber incorporating a Bragg grating, and may also comprise a Fabry-Perot etalon.

A CS optical pulse train generation method, which is able to change the half width of an optical pulse constituting a CS optical pulse train, and which is compact and has low power consumption. A distributed Bragg reflector semiconductor laser utilized in this method is one which is constituted comprising an optical modulation region, a gain region, a phase control region, and a distributed Bragg reflector region. Current is injected into the gain region by way of a p-side electrode and a n-side common electrode by a constant current source, forming the population inversion required for laser oscillation. Optical modulation required to manifest mode locking is carried out in the optical modulation region. A diffraction grating is formed in the distributed Bragg reflector region. A CS optical pulse train with a repetitive frequency of f_rep is generated by adjusting the effective indices of both the phase control region and the distributed Bragg reflector region such that, of the longitudinal modes of the mode-locked semiconductor laser diode, the two longitudinal modes close to the frequency f₀, which is the Bragg wavelength of the distributed Bragg reflector region converted to a frequency, become f₀+(f_rep/2) and f₀−(f_rep/2).

The invention relates to a serial-parallel connection modulation optical frequency multiplication millimeter-wave RoF (Radio Over Fiber) system and a QPSK (Quadrature Phase Shift Keying)/16QAM (Quadrature Amplitude Modulation) modulation method thereof. The system comprises a central station, a base station and fiber connection thereof, wherein the central station comprises a single longitudinal mode laser, a double-electrode Mach-Zehnder optical modulator, an IQ optical modulator, two microwave signal sources, a pi phase shifter, a pi/2 phase shifter and an erbium doped fiber amplifier; and the base station comprises an optical detector, a front low-noise amplifier, two millimeter-wave bandpass filters, two millimeter-wave amplifiers, a millimeter-wave duplexer and a millimeter-wave antenna. In the method, the cascading of the double-electrode Mach-Zehnder optical modulator and the IQ optical modulator is adopted, and a balanced optical waveguide structure formed by integrating the two optical modulators avoids the influence of optical source phase interference noise caused by support arm optical delay inequality on modulation signals.

The invention consists of pumping source, cavity, and a group of coupling device set between the pumping source and cavity, and connected with pumping source through optical fiber. The cavity consists of front cavity mirror and back cavity mirror coated with film. The double-doped crystals and active Q-switch are set between the front and back mirrors. A cooling device is set on the double-doped crystals. The invention features using active Q-switch to control the passive Q-switch for getting prelase pulse, and using saturable absorption crystals as longitudinal mode selector for making the solid single longitudinal mode laser work under higher pumping power.

A single-mode, etched facet distributed Bragg reflector laser includes an AlGaInAs/InP laser cavity, a front mirror stack with multiple Fabry-Perot elements, a rear DBR reflector, and a rear detector. The front mirror stack elements and the rear reflector elements include input and output etched facets, and the laser cavity is an etched ridge cavity, all formed from an epitaxial wafer by a two-step lithography and CAIBE process.

A frequency swept laser source that generates an optical signal that is tuned over a spectral scan band at single discrete wavelengths associated with longitudinal modes of the swept laser source. Laser hopping over discrete single cavity modes allows long laser coherence length even under dynamic very high speed tuning conditions. A ramp drive to the laser is used to linearize laser frequency tuning. A beam splitter is used to divide the optical signal between a reference arm leading to a reference reflector and a sample arm leading to a sample. A detector system detects the optical signal from the reference arm and the sample arm for generating depth profiles and images of the sample.

A system and method for detecting and locating the interface emulsion or rag layer in a separator vessel makes use of an acoustic property approach or an imaging approach. Both approaches use ranging and longitudinal mode reflectance and are non-ionizing. The signals are sent through the fluid medium residing in different zones of the vessel, not through the vessel wall or a probe surrounded by the fluid medium. The acoustic property approach uses differences in acoustic impedance between the oil, rag, and water layers that create an echo detected by transit time measurement. Also, the velocity of sound, density, viscosity and attenuation can be calculated for each fluid in order to determine whether the medium is oil, rag, or water. The imaging approach uses differences in amplitude reflectance at these interfaces to create a brightness mode image of the different layers by each amplitude mode scan line being added spatially.

The invention discloses a single longitudinal-mode optical fiber laser with low noise, narrow linewidth and high power. Polarization maintaining optical fiber is rare-earth-doped phosphate single-mode glass optical fiber, the component of a fiber core is phosphate glass which consists of 70P2O5-8Al2O3-15BaO-4La2O3-3Nd2O3, the fiber core of the polarization maintaining optical fiber is doped with high-concentration luminous ions, the luminous ions are one or combination of more than one of lanthanide ions and transition metal ions, the doping density of the luminous ions is greater than 1*10<19>ions/cm<3> and the luminous ions are evenly doped in the fiber core. A polarization maintaining fiber Bragg grating with the narrow linewidth and a dichroscope form a front cavity mirror and a rear cavity mirror of the optical fiber laser, a centimeter-sized erbium-ytterbium co-doped phosphate glass polarization maintaining optical fiber is taken as a laser working substance, and polarization maintaining output laser generated by a single-mode semiconductor laser is taken as a pumping source, thus achieving the single longitudinal-mode laser output by designing and manufacturing the reflection spectrum width of the polarization maintaining fiber Bragg grating and controlling the cavity length of the whole laser cavity.

This specification discloses a VCSEL (Vertical-Cavity Surface-Emitting Laser) device with single-mode output and optionally single polarization output. This device is given by lateral mode confinement by the PBG (Photonic Band-Gap) effect by shallow etching in a partial VCSEL top mirror. The PBG area encircles a MS-region (Mode-Shaping region), which is characterized by large longitudinal mode losses. The MS-region encircles the LA-region (Light Aperture region), which is characterised by low longitudinal mode losses. The MS-region does not contribute to the lateral mode-confinement to the LA-aperture, and the lateral modes confined by the PBG area. The VCSEL is thus optimized for single fundamental mode operation.