51results about How to "Increase spectral bandwidth" patented technology

Apparatus, method, logic arrangement and storage medium are provided for increasing the sensitivity in the detection of optical coherence tomography and low coherence interferometry (“LCI”) signals by detecting a parallel set of spectral bands, each band being a unique combination of optical frequencies. The LCI broad bandwidth source can be split into N spectral bands. The N spectral bands can be individually detected and processed to provide an increase in the signal-to-noise ratio by a factor of N. Each spectral band may be detected by a separate photo detector and amplified. For each spectral band, the signal can be band p3 filtered around the signal band by analog electronics and digitized, or, alternatively, the signal may be digitized and band pass filtered in software. As a consequence, the shot noise contribution to the signal is likely reduced by a factor equal to the number of spectral bands, while the signal amplitude can remain the same. The reduction of the shot noise increases the dynamic range and sensitivity of the system.

Apparatus and method for increasing the sensitivity in the detection of optical coherence tomography and low coherence interferometry (“LCI”) signals by detecting a parallel set of spectral bands, each band being a unique combination of optical frequencies. The LCI broad bandwidth source is split into N spectral bands. The N spectral bands are individually detected and processed to provide an increase in the signal-to-noise ratio by a factor of N. Each spectral band is detected by a separate photo detector and amplified. For each spectral band the signal is band pass filtered around the signal band by analog electronics and digitized, or, alternatively, the signal may be digitized and band pass filtered in software. As a consequence, the shot noise contribution to the signal is reduced by a factor equal to the number of spectral bands. The signal remains the same. The reduction of the shot noise increases the dynamic range and sensitivity of the system.

An optical reduction system with polarization dose sensitive output for use in the photolithographic manufacture of semiconductor devices having variable compensation for reticle retardation before the long conjugate end. The variable compensation component(s) before the reticle provides accurate adjustment of the polarization state at or near the reticle. The variable compensation components can be variable wave plates, layered wave plates, opposing mirrors, a Berek's compensator and/or a Soleil-Babinet compensator. The catadioptric optical reduction system provides a relatively high numerical aperture of 0.7 capable of patterning features smaller than 0.25 microns over a 26 mm×5 mm field. The optical reduction system is thereby well adapted to a step and scan microlithographic exposure tool as used in semiconductor manufacturing. Several other embodiments combine elements of different refracting power to widen the spectral bandwidth which can be achieved.

The present invention relates generally to a terahertz and millimeter wave source, and more particularly, but not exclusively, to structures for coupling the terahertz electromagnetic waves out of the source.

A multi-wavelength VECSEL includes an active region comprising a plurality of semiconductor quantum wells having an intrinsically broadened gain with a wavelength selective filter disposed within the cavity to provide a laser output that oscillates at two or more separated wavelengths simultaneously. A non-linear crystal may be provided in the cavity to emit radiation at a frequency in the THz range that is the difference of the frequencies associated with two of the separated wavelengths.

The invention provides a method and device for monitoring an optical layer of a passive optical network based on a two-dimensional optical orthogonal code. Each user is identified by using the two-dimensional optical orthogonal code. An optical encoder is added in the front of user equipment. The optical encoder performs optical encoding on a detected optical pulse and reflects an encoded optical signal to a monitoring system. The reflected optical signal is decoded in the monitoring system. The health state of each branch optical fibre is judged through the decoded signal. An optical power detection part in the monitoring system performs fault location and analysis functions simultaneously. In the invention, the link state of an optical network is monitored by adopting the passive optical device without limitation of a network topological structure and branch length. The device disclosed by the invention can identify that a fault is in the user equipment or an optical fibre link, judge the branch in which a fault is and position the specific position of the fault, and support the monitoring of the optical fibre link of the high-user-capacity passive optical network.

A method for modulating fiber optic transmissions with a low sensitivity to fiber non-linearity utilizes short pulses (typically shorter than 20 ps), and bit rates of 10 Gb/s and higher, to improve performance relative to heretofore known nonlinear transmission with Return-to-Zero (RZ) format implementations. At a base bit rate of 40 Gb/s, a distance determination for achieving 100% cumulative dispersion compensation is made, and a predetermined amount of pre-dispersion compensation is applied based on a determined distance using lower duty cycles for transmission. Higher bit rates (i.e., higher than 40 Gb/s) broaden the spectral bandwidth of the transmission and can result in no pre-dispersion compensation or negative distance pre-dispersion compensation of the same sign as the transmission fiber.

Wireless communication is ubiquitous today with increasing deployments leading to increased interference, increasing conflicts, etc. Monitoring the wireless environment is therefore important for regulators, service providers, Government agencies, enterprises etc. Such monitoring should be flexible both in networks monitored within the wireless environment as well as detecting unauthorized transmitters, allowing dynamic network management, etc. However, such real time spectral/signal analysis in the prior art requires both a wideband direct conversion receiver (DCR), for high performance, wideband, fast, programmable spectral analysis, and a super heterodyne receiver for fast, narrowband, programmable demodulation for signal analysis. According to embodiments of the invention a single receiver design methodology exploiting a single RF circuit to provide superheterodyne and direct conversion receiver functionalities.

The invention is applicable to the technical field of laser and provides a double chirped spectrum optical parametric amplifier and an amplification method. The double chirped spectrum optical parametric amplifier is characterized in that pump light and signal light in time synchronization are generated by a femtosecond laser component and independently pass through an input grating and an input collimating lens to make different spectral components of the signal light and the pump light linearly dispersively focused on respective focal points to realize spatial chirps opposite in frequency change rate signs in focal planes; then on the basis of sector-shaped periodic polar crystal, efficient full-spectrum optical parametric amplification of the signal light is completed through the pump light, and broadband-spectrum idler-frequency light is generated; finally, a spectroscope is adopted for separating out the broadband-spectrum idler-frequency light, Fourier transformation from a spectral domain to a time domain is completed through an output collimating lens and an output grating, and necessary dispersion compensation is performed to obtain long-wavelength ultra-short pulse laser. The optical parametric amplifier is simple in structure, and the long-wavelength ultra-short pulse laser can be obtained.

Fiber optic sensors employ a high brightness light source such as a fiber optic supercontinuum source, multiplexed superluminescent light emitting diodes, or a broadband tunable laser diode. Light is delivered to the measurement location via fiber optics and sensor optics directs infrared radiation onto material the being monitored that is located in a hostile environment. A disperse element is positioned in the detection beam path in order to separate the wavelengths and to perform spectral analysis. A spectral analysis of the radiation that emerges from the sheet yields information on a plurality of parameters for the material. For papermaking applications, the moisture level, temperature and cellulose content in the paper can be obtained.

A laser system for a spectroscopic catheter system uses multiple semiconductor gain media having gain peaks at different wavelengths. The output from the gain media is preferably coupled into single-mode fiber using conventional opto-electronic packaging techniques. As a result, the laser oscillator source has a spectral output that is wider than the gain bandwidth of a single medium to enable it to access the entire spectrum of interest, which is presently in the near infrared. Moreover, the semiconductor gain media can be packaged in a stable and controlled environment for long-term performance.

A system and method for resampling interference datasets of samples in segments, in a swept-source based Optical Coherence Tomography (OCT) system. The resampling is preferably performed within a Field Programmable Gate Array (FPGA) of the OCT system, the FPGA preferably having Fourier-transform based signal processing capabilities such as Fast Fourier Transform (FFT) cores. Resampling the interference datasets in segments provides a flexible approach to resampling that makes efficient use of system resources such as FFT cores. By resampling the interference datasets in segments, the system adjusts to an increased number of resampling points as the imaging depth upon the sample increases. The OCT system then combines the segments using overlapping values of the resampling points between adjacent resampling regions of the resampled segments, and performs Fourier Transform based post-processing on the combined segments to obtain axial profiles of the sample at desired imaging depths.

Compact laser systems are disclosed which include ultrafast laser sources in combination with nonlinear crystals or waveguides. In some implementations fiber based mid-IR sources producing very short pulses and/or mid-IR sources based on a mode locked fiber lasers are utilized. A difference frequency generator receives outputs from the ultrafast sources, and generates an output including a difference frequency. The output power from the difference frequency generator can further be enhanced via the implementation of large core dispersion shifted fibers. Exemplary applications of the compact, high brightness mid-IR light sources include medical applications, spectroscopy, ranging, sensing and metrology.

The invention discloses red fluorescence powder for laser medical-treatment illumination and a preparation method and application thereof. The chemical formula of the red fluorescence powder is M1-x-zLixAl1-x-ySi1+x+yN3-yCy:zEu<2+> or M1-m+0.5n-pLimAl1-mSi1+mCnN3-n:pEu<2+>, wherein the x and the m are 0.01-0.3, the y and the n are 0.01-0.30, and the z and the p are 0.001-0.3. According to the preparation method of the red fluorescence powder for laser medical-treatment illumination, the fluorescence powder having good luminescence property is prepared by utilizing a high-temperature solid-state method and doping different atoms. In addition, the specific temperature is adopted for calcination, calcining reaction is performed at the temperature of 1500-1900 DEG C for 1-20 hours to enable components to be better bound together and to play excellent optical properties, and the red fluorescence powder is very suitable for manufacturing of medical-treatment illumination sources.