115 results about "Sum-frequency generation" patented technology

A measurement system, comprising: a first light source that generates first light and irradiates an object with the first light, at least one of an intensity, a polarization state, and a wavelength being modulated with a first period in the first light; a second light source that generates second light, at least one of an intensity, a polarization state, and a wavelength being modulated with a second period in the second light; a first optical system that mixes light from the object based on the first light with the second light; a nonlinear optical crystal that generates third light from the mixed light by sum-frequency generation phenomenon, the third light having a frequency equivalent to a sum of a frequency of the light from the object based on the first light and a frequency of the second light; and a photodetector that measures an intensity of the third light.

A “Folded Cavity Surface Emitting Laser” (FCSEL) sum frequency generating device capable of generating a second harmonic at room temperatures with high efficiency and output power, while having a small size, low energy consumption, and a low manufacturing cost. A FCSEL sum frequency generating semiconductor diode laser has a multilayered structure that comprises a mode discriminating polyhedral shaped prism waveguide, which is located at one end of two light emitting diodes, a partial photon reflecting mirror, which is located at the opposite end of the two light emitting diodes, and a phase-matching sum-frequency generating superlattice, which is located between the polyhedral shaped prism waveguide and the partial photon reflecting mirror.

An increased frequency power generator that includes a pair of transducers located on opposite sides of a suspended inertial mass. Magnetic attraction is used to couple the mass to each of the two transducers in alternating fashion in response to vibration and other movement externally imparted on the generator. Each transducer includes a suspended magnetic element that couples and decouples to the inertial mass as it reciprocates in the housing due to the applied external moving force. As the inertial mass decouples from one transducer on its way to magnetically connecting to the other transducer, the decoupled suspended magnetic element oscillates at a frequency greater than the imparting force, thereby generating electrical power.

A wideband frequency generator has two or more oscillators for different frequency bands, disposed on the same die within a flip chip package. Coupling between inductors of the two oscillators is reduced by placing one inductor on the die and the other inductor on the package, separating the inductors by a solder bump diameter. The loosely coupled inductors allow manipulation of the LC tank circuit of one of the oscillators to increase the bandwidth of the other oscillator, and vice versa. Preventing undesirable mode of oscillation in one of the oscillators may be achieved by loading the LC tank circuit of the other oscillator with a large capacitance, such as the entire capacitance of the coarse tuning bank of the other oscillator. Preventing the undesirable mode may also be achieved by decreasing the quality factor of the other oscillator's LC tank and thereby increasing the losses in the tank circuit.

In order to generate efficiently a deep ultraviolet laser beam having a wavelength in a deep ultraviolet region and to make the generated laser beam to be high output, it is arranged in such that a laser beam having about 227 nm wavelength is generated by sum-frequency mixing of fourth harmonic of the laser beams obtained by amplifying semiconductor laser beams having 1064.0 to 1065.0 nm wavelengths by means of an optical fiber amplifier, and the laser beams obtained by amplifying semiconductor laser beams having 1557.0 to 1571.0 nm wavelengths by means of another optical fiber amplifier; and further laser beams having 198.4 to 198.7 nm wavelengths are generated by sum-frequency mixing of the above sum-frequency mixed laser beam and the above-described semiconductor laser beams having 1557.0 to 1571.0 nm wavelengths.

Optical systems operable to emit multiple frequency-converted spectral peaks are provided. In one embodiment, an optical system includes an optical source and a wavelength conversion device. The optical source may include a laser configured to emit a pump beam having at least two fundamental spectral peaks. The wavelength conversion device may include a non-linear optical medium configured to phase match the second harmonic generation of each of the at least two fundamental spectral peaks and sum-frequency generation of the at least two fundamental spectral peaks such that an output beam comprising at least three frequency-converted spectral peaks having approximately equal power is emitted from an output facet of the wavelength conversion device when the pump beam of the optical source is incident on an input facet of the wavelength conversion device.

The present invention relates to method for spectrally equalized frequency comb generation. In order to carry this method, the following steps are followed: seed laser or lasers are modulated to acquire frequency chirp necessary to enable temporal compression and an increase in peak optical intensity necessary for an efficient nonlinear optical mixing process to occur; the compressed waveform is reshaped by nonlinear-transfer optical element and subsequently used to generate frequency comb in nonlinear waveguide. Ultimately, at the conclusion of these steps, a frequency comb is generated with substantially flat optical spectrum, while retaining variability with respect to the frequency pitch, high coherency and substantially wide spectral band of coverage.

The invention relates to methods and apparatus for modifying the frequency characteristics of a spatially-dispersed mid-IR spectra for spectroscopy. In a preferred embodiment, sum frequency generation between a frequency-dispersed IR beam and an ultrafast optical pulse generates a spatially-extended optical signal that is collected with a CCD detector.

Stabilization of an injection locked optical frequency comb is achieved through polarization spectroscopy of an active laser cavity, eliminating optical PM sidebands inherent in previous stabilization methods. Optical SNR of 35 dB is achieved. A monolithic AlInGaAs quantum well Fabry-Prot laser injection locked to a passively mode-locked monolithic laser is presented here. The FP laser cavity can be used as a true linear interferometric intensity modulator for pulsed light.

A multi-channel optical frequency mixer for all-optical signal processing and a method for engineering the same. The multi-channel mixer uses a nonlinear optical material exhibiting an effective nonlinearity d_eff whose spatial distribution is defined by a quasi-phase-matching grating, e.g., a QPM grating. The spatial distribution is defined such that its Fourier transform to the spatial frequency domain defines at least two wavelength channels which are quasi-phase-matched for performing optical frequency mixing. The wavelength channels correspond to dominant Fourier components and the Fourier transform is appropriately adjusted using grating parameters such as grating periods, phase reversal sequences and duty cycles to include an odd or even number of dominant Fourier components. The multi-channel mixer can perform frequency mixing operations such as second harmonic generation (SHG), difference frequency generation (DFG), sum frequency generation (SFG), and parametric amplification.

The invention relates to a system integration device and a system integration method of test parameters based on the unit combination. The device comprises a main control computer and an exchange board, and also comprises a switch unit, a lower variable-frequency generation unit, a digitalized instrument generation unit, a base band signal generation unit and an upper variable-frequency generation unit, which are connected and communicated with one another; the lower variable-frequency generation unit is matched with the digitalized instrument generation unit and used for receiving and testing a test signal; and the base band signal generation unit is matched with the upper variable-frequency generation unit and used for generating and transmitting an excitation signal. By adopting the scheme, a test system with high performance and low cost is easy to establish, and different instrument functions can be realized by maximally utilizing fewest standard universal units.

An optical sampling method and apparatus use a probe pulse source of a predetermined optical wavelength range, e.g., 1560 nm, to sample incoming optical pulses in approximately the same wavelength range. The probe pulse source is frequency-doubled e.g., using a frequency doubler such as a nonlinear PPLN crystal, to obtain an intermediate second harmonic which may be filtered with a 780 nm bandpass filter to eliminate at least source frequency noise background. The filtered intermediate second harmonic is then mixed with the user input signal using an optional polarizing beam splitter and a dichroic beam splitter. The mixed signal is sent to a sum frequency generating (SFG) nonlinear crystal, e.g., a PPLN crystal, where the resulting frequency is near the third harmonic. The output from the SFG PPLN crystal may be filtered using a bandpass 515 nm filter to remove unwanted wavelengths and processed to measure/sense the near third harmonic content using a photomultiplier tube (PMT). Beyond the PMT, the output may be sent to a microprocessor for analysis and display on a cathode ray oscilloscope as necessary. 80-85% power conversion efficiency in the frequency doubler, a 60 or 65% photon conversion efficiency in the sampler and handling of 600+ GHz bandwidths, as well as background noise reduction are possible by using the invention.

Embodiments of the invention are concerned with a radar system, and relates specifically to scanning radar systems that are suitable for detecting and monitoring ground-based targets.

In one aspect, the radar system is embodied as a scanning radar system comprising a frequency generator, a frequency scanning antenna, and a receiver arranged to process signals received from a target so as to identify a Doppler frequency associated with the target, wherein the frequency generator is arranged to generate a plurality of sets of signals, each set having a different characteristic frequency, the frequency generator comprising a digital synthesiser arranged to modulate a continuous wave signal of a given characteristic frequency by a sequence of modulation of patterns whereby to generate a said set of signals, and wherein the frequency scanning antenna is arranged to cooperate with the frequency generator so as to transceive radiation over a region having an angular extent dependent on the said generated frequencies.

Embodiments of the invention thus combine digital synthesiser techniques, which are capable of precise frequency generation and control, with passive frequency scanning and Doppler processing techniques. This enables accurate control of range and of scan rates, and enables optimisation of range cell size for factors such as slow and fast target detection and Signal to Noise ratio, and thus enables detection of targets located at distances considerably farther away than is possible with known systems having similar power requirements.

A solid state atomic clock may utilize quantum states capable of exhibiting a hyperfine resonance in order to generate a frequency standard. A device capable of coupling a free running oscillator to the hyperfine resonance frequency in order to generated output signal is described herein. In some aspect of the invention, the atomic clock may be fabricated on a silicon substrate and it may be integrated, in chip scale, as part of an electronic integrated circuit. The principal of operation, the method of making and system which utilized a solid state atomic clock are also disclosed.

A nonlinear solid-state device useful for frequency conversion of electromagnetic radiation and in particular for harmonic generation, comprising a waveguiding electromagnetically distributed structure (WEDS) which includes monolithically a synthetic nonlinear material (SNM). Input radiation coupled into the WEDS is converted into a higher frequency output radiation through a constricted oscillatory motion of charge carriers and phase matched harmonic frequency generation of radiation which builds up coherently over an interaction length many time larger than the radiation wavelengths. In one embodiment, microwave radiation is converted into terahertz radiation. In other embodiments, SNM based WEDS devices are adapted for frequency mixing and parametric oscillation.

Pulsed, coherent light is generated by optical mixing which takes place inside the resonator of a pulsed laser oscillator. One of the beams to be mixed is generated by the pulsed laser, and the other by a distinct, external laser oscillator. If the light from the external oscillator is modulated, that modulation will be transferred onto the light generated by the optical mixing. This enables modulated light at an expanded range of wavelengths. Using sum frequency generation, light for sodium excitation, such as for a guide star, can be generated with the optimal modulation of spectral and temporal properties. If the type of optical mixing is difference frequency generation, optical parametric amplifiers with improved efficiency and beam quality are enabled.

The present invention discloses a means of the generation of tunable femtosecond pulses from 380 nm to 465 nm near the degenerate point of a 405-nm pumped type-I BBO non-collinearly phase-matched optical parametric amplifier (NOPA). The tunable UV/blue radiation is obtained from sum frequency generation (SFG) between the OPA output and the residual fundamental beam at 810-nm and cascaded second harmonic generation (SHG) of OPA. With a pumping energy of 75 mJ at 405 nm, the optical conversion efficiency from the pump to the tunable SFG is more than 5% and the efficiency of SHG of the OPA is about 2%.

The invention discloses a self Raman yellow light laser of a composite cavity structure. A laser diode pumping source emits pump light in an absorption belt of a gain medium, the pump light is focused inside the gain medium through a transmitting energy fiber and a coupling lens set, the gain medium absorbs the pump light to form population inversion, and base frequency laser generation is formed under the feedback action of a laser resonant cavity composed of a resonant cavity shared reflector and a laser total reflector; when base frequency laser passes through the gain medium, Raman gains are generated, and after the Raman gains are greater than the cavity loss of a Raman resonant cavity composed of the resonant cavity shared reflector, a beam splitter and a yellow light output mirror, stable Stokes light generation is formed in the Raman resonant cavity; the frequency of Stokes light is doubled in a frequency doubling crystal, and the generated yellow light secondary harmonic wave is output by the yellow light output mirror. The composite cavity structure is adopted, the length of a base frequency laser resonant cavity is largely decreased, and therefore the stable area of the resonant cavity is effectively enlarged, and the effect of improving the output power of the self Raman yellow light laser is achieved by applying higher pumping power.

A wavelength conversion module according to the present invention includes an external resonator, a semiconductor laser module and a wavelength conversion device for converting a wavelength of light output from the semiconductor laser module into a shorter wavelength. This wavelength conversion device includes at least one of a nonlinear crystal for generating SFG (Sum-frequency Generation) light and a nonlinear crystal for generating SHG (Second Harmonic Generation) light. Each of the SFG generating element and the SHG generating element of the wavelength conversion device may have a periodically-poled ridge-waveguide structure or a periodically-poled proton-exchanged-waveguide structure.

A laser apparatus generating frequency converted light. Embodiments of the laser apparatus described herein apply a cascade of nonlinear frequency mixers for sum frequency generation (SFG) or difference frequency generation (DFG) between two frequency components of a spectrally combined laser beam with at least two spectral components originating from two respective laser sources, SFG of two frequency components beams offers up to a factor of four amplification of output power over SHG of a single laser beam.