39 results about "Laser phase noise" patented technology

This invention relates to a distributed disturbance sensing device based on polarization sensitive optical frequency domain reflectometry (OFDR) and the related demodulation thereof. The device, adopting OFDR, polarization controlling and analysis techniques, consists of a ultra-narrow linewidth tunable laser source module, polarization generating and polarization splitting balanced detecting module, laser source optical frequency and phase monitoring module, high-speed optical switch and so on to establish a large-scale and long-distance optical sensing network. The demodulation method consists of analysis the polarization information from sensing optical fiber, the method of suppressing and compensating of the non-linear optical frequency and the laser phase noise, super-resolution analyzing, advanced denoising method and the polarization information analysis method based on Jones and Mueller's matrices using distributed wave plate model of optical fiber.

A quantum random number generator based on laser phase noise, belonging to the technical field of quantum security communication, comprising a laser, a path selection module, an interferometer, a first photodetector, a second photodetector, a data acquisition and processing module, a modulus A converter, a first temperature control module and a phase stabilization module, the interferometer includes a first beam splitter, an optical fiber delay line and a dual-channel phase stabilization reflection module. Compared with the prior art, the present invention adopts the dual-channel phase-stabilized reflection module, so that the two-channel optical signals propagating along the long and short arms of the interferometer pass through the same reflection device, so that the polarizations of the two are completely consistent, and the interferometer is improved. The interferometric stability; using the difference between the electrical signals of the two photodetectors as the feedback signal for the phase compensation of the interferometer, and using the sum of the electrical signals of the two photodetectors as the feedback signal for the stable control of the laser power to control the optical system Carry out overall stability control to further improve the stability and practicability of the system.

The present invention relates to a method and device for reducing the phase noise of a laser signal from a laser source. This device comprises a first current generator for supplying a driving current to the laser source in view of producing the laser signal. A phase noise detector is responsive to the laser wavelength for generating a phase error signal and a second current generator is responsive to the phase error signal for generating a compensation current added to the driving current supplied to the laser source for generating a phase-adjusted laser signal. The device therefore defines a phase stabilization loop formed by the phase noise detector and the second current generator, for reducing the phase noise of the laser signal.

A high resolution measurement method and apparatus for tracking wavelength transients in tunable lasers. The apparatus comprises a Mach-Zehnder interferometer (MZI) which is used to generate a self-heterodyne signal between the wavelength transient to be measured, which is effectively the laser signal passed along the time-delayed arm of the MZI, and the laser wavelength after the tuning transient has subsided, which is effectively the same laser signal passed along the direct arm of the MZI. The heterodyne signal is detected on a receiver, and can then be measured with the frequency resolution typical of electronic measurements, such as by means of an oscilloscope. The only laser required is the laser under inspection. The wavelength measurement accuracy is up to twice the laser linewidth, and is only effectively limited by the laser phase noise. The method can be used to implement an automatic frequency control system for tunable lasers.

The invention relates to a self-adaptive damage compensation method and system for a digital-related optical communication system. The self-adaptive damage compensation method includes inserting two pulse modulation pilot frequency signals symmetrically distributed on an input signal frequency fc (fiber channel) at a transmitting terminal; acquiring an input signal power spectrum by the Fourier transform at a receiving terminal, and receiving the pilot frequency signals of a signal power spectrum and subjecting the pilot frequency signals to location and filtering extraction; calculating size of frequency offset of a vibration laser and performing compensation by a pilot frequency; acquiring pilot time domain waveforms by the Fourier transform and calculating a delay delta tau between two pilot light pulses, and calculating size of dispersion by the delta tau and performing the compensation; finally extracting pilot phase noises and subtracting the same from a signal phase so as to eliminate laser phase noises and nonlinear fiber damages. The self-adaptive damage compensation method has the advantages of high accuracy, low complexity, small occupation of bandwidth and fast response speed, so that self-adaptive compensation of various damages can be realized.

The invention provides a laser phase noise-based miniature random number generator. The random number generator comprises a laser device, a coupler, a photoelectric detector, an analog-digital converter and a post-processing module, wherein the laser device generates continuous light or pulse light; the continuous light or the pulse light generates interference at the coupler, and phase noises are converted into an intensity signal; the coupler is connected with the photoelectric detector, and the intensity signal is subjected to photoelectric conversion through the photoelectric detector; the photoelectric detector is connected with the analog-digital converter, and the analog-digital converter performs quantification on an output electric signal of the photoelectric detector to obtain an initial random bit; and the post-processing module performs randomness optimization on the initial random bit to obtain a final random bit. Compared with the prior art, the random number generator has the advantages that an output result is stable, random number generation does not depend on polarization and phase compensation technologies, and the random number generation speed is high.

The invention belongs to the field of optical communication, and particularly relates to a phase noise estimation method for a multi-core optical fiber and application of the phase noise estimation method, the estimation method comprises the following steps: calculating variance of laser phase noise based on a laser phase noise model and line width of a laser adopted in a multi-core optical fibercommunication system; based on the variance of the laser phase noise, calculating the variance of the crosstalk phase noise, wherein the variance of the crosstalk phase noise is in direct proportion to the variance of the laser phase noise; based on the crosstalk model of the multi-core optical fiber, constructing a multi-dimensional orthorhombic variance matrix corresponding to the multi-core optical fiber to serve as the variance of the phase noise of the multi-core optical fiber, diagonal elements of the matrix being the variance of the phase noise of the laser, and non-diagonal elements ofthe matrix being the variance of the crosstalk phase noise; and calculating to obtain the phase noise of the multi-core optical fiber based on the multi-dimensional orthorhombic variance matrix. According to the invention, the inter-core crosstalk of the phase noise of different fiber cores in the multi-core optical fiber is considered, the accuracy is high, and an efficient premise is provided for the compensation of the phase noise of the multi-core optical fiber.

Embodiments of the present disclosure provide a signal processing apparatus, a signal transmitting apparatus and a receiver, which are adapted for a frequency division multiplexing system having a high-order modulation format. A receiver having a high-magnification sampling rate by inserting a pilot signal between neighboring subcarriers at a transmitter side, calculating a laser phase noise according to a phase of the pilot signal at a receiver side, and performing down-sampling and equalization processing after performing carrier phase recovery according to the laser phase noise, so that a laser phase noise having a wide frequency may be accurately compensated, thereby having a relatively powerful carrier phase recovery ability.