46results about How to "Reduce Relative Intensity Noise" patented technology

Apparatus, method and storage medium which can provide at least one first electro-magnetic radiation to a sample and at least one second electromagnetic radiation to a reference, such that the first and/or second electromagnetic radiations have a spectrum which changes over time. In addition, a first polarization component of at least one third radiation associated with the first radiation can be combined with a second polarization component of at least one fourth radiation associated with the second radiation with one another. The first and second polarizations may be specifically controlled to be at least approximately orthogonal to one another.

Methods are disclosed for producing highly doped semiconductor materials. Using the invention, one can achieve doping densities that exceed traditional, established carrier saturation limits without deleterious side effects. Additionally, highly doped semiconductor materials are disclosed, as well as improved electronic and optoelectronic devices/components using said materials. The innovative materials and processes enabled by the invention yield significant performance improvements and/or cost reductions for a wide variety of semiconductor-based microelectronic and optoelectronic devices/systems. Materials are grown in an anion-rich environment, which, in the preferred embodiment, are produced by moderate substrate temperatures during growth in an oxygen-poor environment. The materials exhibit fewer non-radiative recombination centers at higher doping concentrations than prior art materials, and the highly doped state of matter can exhibit a minority carrier lifetime dominated by radiative recombination at higher doping levels and higher majority carrier concentrations than achieved in prior art materials. Important applications enabled by these novel materials include high performance electronic or optoelectronic devices, which can be smaller and faster, yet still capture or emit light efficiently, and high performance electronics, such as transistors, which can be smaller and faster, yet cooler.

A multi-wavelength light source includes a substrate, a fabry-perot laser laminated on the substrate that is operated by driving current below a predetermined threshold current to generate multi-wavelength light including a plurality of peaks whose wavelengths and spacing are identical to these of WDM channels. A semiconductor optical amplifier (SOA) is laminated on the substrate in an arrangement such that a slant surface of the SOA is opposed to a side surface of the fabry-perot laser, which serves to thereby amplify the multi-wavelength light output from the fabry-perot laser. The semiconductor optical amplifier is driven in a gain saturation state to reduce the relative intensity of noise in the channels of the multi-wavelength light that are simultaneously amplified.

A beam of coherent laser light with linear polarization oriented at 45 degrees to vertical is expanded, and passes through a quarter-wave plate with the fast axis oriented vertically, creating circularly polarized light. The light then passes through a non-polarizing 50/50 beamsplitter. A partial reflector then collinearly reflects a portion of the beam, which is used as the reference beam. The transmitted light passes through a linear polarizer oriented at 45 degrees to vertical, and is focused via a lens onto the sample of interest. Light scattered from this region is re-collimated by the lens and the directed through the linear 45 degree polarizer and through the partial reflector, where it recombines with the reference beam. One use of the invention is to detect microparticles in water.

The invention discloses a vibration sensing device based on a photoelectric oscillator, and the device comprises a laser, a one-in-two optical coupler, an optical phase shifter, a sensing head, a polarization controller, a Mach-Zehnder modulator, a two-in-one optical coupler, an energy-storage optical fiber, a photoelectric detector, a band-pass filter, a radio frequency amplifier, a 3dB power divider, a reference oscillator, a frequency mixer, a low-pass filter, an analog-to-digital converter, and an upper computer. According to the invention, one arm of the Mach-Zehnder modulator serves as the sensing head, thereby improving the sensitivity of vibration signal detection, and improving the detection precision. Compared with other passive optical fiber sensors, the device enables vibration information to be coded on the frequency of the vibration signal not the intensity, so the device is not sensitive to the impact from the power fluctuation of a light source. Compared with an optical fiber based on an optical fiber laser, the device is higher in sensitivity, and the sensitivity of the device is not related with the oscillation frequency. The device can be implemented through a low-cost low-frequency device, and is high in practicality.

A method and apparatus for producing single mode random fiber ring laser by inducing random distributed feedback in a short section of the fiber ring to thereby enable single mode lasing while reducing frequency jitter and relative intensity noise. The random distributed feedback maybe achieved through deep refractive index modulation at a series of randomly distributed laser-irradiated points inscribed along the length of the induced random distributed feedback fiber. The laser-processed random distributed feedback fiber maybe incorporated into the fiber ring in conjunction with a variable optical attenuator and band pass optical filter for enhancing the single mode operation.

A second harmonic generation laser system comprising: a non-linear frequency converting medium; and an external cavity pump laser that produces optical energy at a single mode and at a single frequency and that is disposed to provide the optical energy to the non-linear frequency converting medium.

The invention discloses an optical fiber acoustic sensing system based on broadband weak reflecting mirrors and random laser, and is applied to the field of photoelectric transmission. A broadband weak reflecting mirror array is written in a sensing optical fiber so that the random laser generated by pump light through coherent feedback can be realized and the power of the pump light can be increased. The random laser provides distributed Raman amplification for the signal light of a detection light source. The distributed Raman amplification can be used for compensating the insertion loss of the broadband weak reflecting mirror array, amplifying the feedback light and enhancing the optical signal-to-noise ratio so as to enhance the detection fallibility and acquire high spatial resolution by controlling the space between the adjacent broadband weak reflecting mirrors. Random laser amplification has lower relative intensity noise so as to acquire the low-noise distributed amplification.

A semiconductor laser module including a semiconductor laser device having an integrated diffraction grating configured to output a multiple mode laser beam in the presence of a driving current, an optical fiber configured to guide the multiple mode laser beam to an output of the laser module, and an optical attenuation device configured to attenuate the multiple mode laser beam by an amount sufficient to provide a predetermined output power from the output of the laser module. The optical attenuation device may be an optical coupling lens offset from an optimum coupling position by an amount sufficient to provide the predetermined output power, or an optical attenuator interrupting the optical fiber and configured to attenuate the multiple mode laser beam by an amount sufficient to provide the predetermined output power. Also, a two fiber Raman amplifier having a super large area (SLA) fiber that provides amplification of the signal based primarily on the forward excitation light can also be used to suppress SBS.

The invention discloses an optical fiber interferometer sensor disturbance signal demodulation device based on single sideband frequency modulation. The optical fiber interferometer sensor disturbancesignal demodulation device based on the single sideband frequency modulation comprises a laser, a modulator, a frequency modulation source, an optical filter, an optical amplifier, an optical isolator, a Michelson interferometer, a PZT, a photodetector and a data sampling card. The optical fiber interferometer sensor disturbance signal demodulation device based on the single sideband frequency modulation disclosed by the invention introduces a microwave frequency modulation source and uses a frequency sweeping method, so as to avoid high requirements of the traditional internal modulation PGCmethod for a direct modulation laser source and reduce a relative intensity noise; and the invention adopts a 12-point quadrature demodulation algorithm to avoid additional electrical noise caused bythe use of an electric mixer, therefore, the measurement dynamic range is large and fully automatic measurement can be realized, the demodulation algorithm is simplified, and the cost is reduced; meanwhile, the system disclosed by the invention can effectively detect array sensors of any distribution, so that the applicability of the system is stronger.

A vertical cavity surface-emitting laser including: a substrate having a main surface; and a post structure mounted on the main surface. The post structure includes an active layer and a carrier confinement structure. The carrier confinement structure includes a first region and a second region having a higher resistivity than the first region. The first region has an edge, and a first to a third reference line segments. A first length of the first reference line segment is longest among lengths of line segments joining any two points on the edge and extending in a [1-10] direction of the III-V group semiconductor. The first length is greater than a sum of a second length of the second reference line segment and a third length of the third reference line segment. The third length is smaller than the second length and is zero or more.

The invention discloses a fiber-optic gyroscope and a relative intensity noise suppression device and method thereof. A path of redundant light is led out by utilizing the blind end of an optical fiber coupler, the redundant light is reflected back to the optical fiber coupler after being attenuated twice by an optical fiber attenuator and rotated by 90 degrees through polarization of an optical fiber Faraday rotation reflector, and in the optical fiber coupler, the signal light and the reflected and attenuated light are subjected to intensity superposition and do not interfere with each other, so that the purpose of reducing relative intensity noise is achieved. According to the device, on the basis of only utilizing the idle blind end of the optical fiber coupler, an optical fiber attenuator and a single-mode optical fiber Faraday rotating reflector are additionally arranged, so that the suppression purpose can be achieved, the structure is simpler, the cost is low, the advantage ofhigh cost-effectiveness ratio of noise suppression is achieved, and the device has important application and popularization value.

The invention discloses a random four-state modulation method of a digital closed-loop fiber-optic gyroscope. The random four-state modulation method of the digital closed-loop fiber-optic gyroscope comprises the steps that a pseudo-random number generator is utilized to generate a pseudo-random number sequence, and a multi-state modulation state memory and state transition moment are established;a random modulation state selector is constructed, a random pseudo-random number is selected, and a modulation state is selected from the multi-state modulation state memory; state transition outputis completed according to the pseudo-random number and the modulation state combined with a state transition matrix; a modulation state delayer is established, a random modulation four-state phase position is generated, and based on the random modulation four-state phase position, a demodulation mark is generated in a combined mode; and the demodulation of the fiber-optic gyroscope angular rate and 2 pi voltage is completed by using the demodulation mark. According to the technical scheme of the random four-state modulation method of the digital closed-loop fiber-optic gyroscope, aiming at theproblems of gyroscope random drift and dead zones caused by electronic crosstalk between modulation signals and demodulation signals of the digital closed-loop fiber-optic gyroscope, the random four-state modulation method of the digital closed-loop fiber-optic gyroscope is adopted, the precision of the fiber-optic gyroscope can be improved, the working stability of the fiber-optic gyroscope is ensured, and the random four-state modulation method of the digital closed-loop fiber-optic gyroscope has great practical significance.

An apparatus for controlling, monitoring, and communicating with an optical device, photonic integrated circuit or subassembly is provided. The apparatus includes an optical device or subassembly; and a field programmable device including programmable hardware gates coupled to the optical device or subassembly. The field programmable device may be configured to implement a plurality of functions at a gate level for controlling, monitoring, and/or communicating with the optical device or subassembly, each of the plurality of functions being configured to execute as a concurrent process, without use of a microprocessor or a microcontroller. Further, a programmable optical device, such as a programmable optical transmitter, optical subassembly, or transceiver based on a tunable laser having field programmable device centric control systems with software-enabled features offer extensive real-time control and monitoring functionality based on for example actual traffic flows.

The invention provides a linear polarization narrow linewidth external cavity type semiconductor laser, which comprises a gain chip and an external cavity frequency selection device. The basic structure of the external cavity frequency selection device is a silicon-based waveguide Bragg grating, and based on the birefringence effect of the silicon-based waveguide Bragg grating, the TE mode and the TM mode reflected by the external cavity frequency selection device are split. And when the TE mode and the TM mode are reflected back to the gain chip and injected to the ASE spectrum of the gain chip, a gain difference is formed between the TE mode and the TM mode, and the gains of the TM mode and the TM mode are inhibited, so that the linear polarization narrow linewidth external cavity type semiconductor laser outputs in a linear polarization mode. Linear polarization laser can be output without a polarization controller, so that the structure of the external cavity semiconductor laser is simplified, and loss among components in the external cavity semiconductor laser is reduced.