441 results about "Stimulated raman" patented technology

A method and apparatus that reduces laser speckle by using stimulated Raman scattering in an optical fiber. The pulse repetition frequency of the laser is adjusted to control aspects of the laser light such as color or despeckling. In DLP projection systems, an optical monitor may be used to send information to a bit sequence, and the bit sequence may control the pulse repetition frequency of the laser based on the optical monitor signal.

Decreasing the average transmitted power in an optical fiber communication channel using multilevel amplitude modulation in conjunction with Pulse Position Modulation (PPM). This multilevel PPM method does not entail any tradeoff between decreased power per channel and channel bandwidth, enabling a lower average transmitted power compared to On / Off Keying (OOK) with no reduction in aggregate data rate. Therefore, multilevel PPM can be used in high-speed Dense Wavelength Division Multiplexed (DWDM) systems where the maximum number of channels is traditionally limited by nonlinear effects such as self-phase modulation (SPM), cross-phase modulation (XPM), four-wave mixing (FWM), stimulated Brillouin scattering (SBS), and stimulated Raman scattering (SRS). This modulation technique can enable an increased number of channels in DWDM systems, thereby increasing aggregate data rates within those systems.

A method and apparatus for generating and transmitting high energy optical pulses are described. Distributed temperature sensors usually use Raman scattering in optical fibres as the means to determine the temperature. Here, light from a laser source is sent down a fibre and the small amount of light that is scattered back towards the source is analysed. As the fibre length increases, the resolutions of the temperature and loss measurements become poorer. This is because losses in an optical fibre attenuate the signal. An obvious solution to this problem is to launch more light into the fibre to compensate for the losses but stimulated Raman scattering limits how much light may be launched. The present invention solves this problem by using a pulse conversion method to maximise the resultant pulse energy while the power is kept below SRS threshold.

This invention pertains to an optical device and method for using a chalcogenide glass waveguide to amplify a pump light beam by means of stimulated Raman scattering and obtaining a depleted pump light beam and an amplified beam at a wavelength higher than the wavelength of the depleted pump light beam.

The invention relates to a random-distribution feedback optical fiber laser which can realize stable, space-irrelevant and continuous laser output, and belongs to the technical field of the optical fiber laser. The random-distribution feedback optical fiber laser comprises a pump laser, a wavelength division multiplexer, a fiber bragg grating, an Er-doped optical fiber, an optical fiber Raman laser and a long monomode optical fiber. The reflection effect of the fiber bragg grating is combined with the distributed Rayleigh scattering effect of the optical fiber to form a distributed random feedback optical resonant cavity; and the light is subjected to gain amplification by an Er-doped optical fiber and the stimulated Raman scattering effect. Compared with the random-distribution feedback optical fiber laser reported before, the threshold value of the pump laser and the length of the monomode optical fiber can be reduced, and the limitation on stimulated emission wavelength and the wavelength number by a Rayleigh gain peak is broken through, thereby realizing the purpose of tuning the laser wavelength. The random-distribution feedback optical fiber laser is suitable for fields, such as remote optical fiber sensing, remote communication and the like.

The invention provides a high-power high-efficiency supercontinuum source. By reasonably designing characteristics of photonic crystal fibers, long-pulse pump laser (picosecond, nanosecond laser) acts on a normal dispersion area for the photonic crystal fibers, the central wavelengths of stimulated front stages of Raman-Stokes peaks are positioned in an abnormal dispersion area close to a zero dispersion point of the photonic crystal fibers, and the stimulated Raman-Stokes laser peaks serve as a new pump source for stimulating supercontinuum and meet the requirement of an abnormal dispersion pump mechanism. The supercontinuum source simultaneously has the advantages of a normal dispersion pump mechanism and the abnormal dispersion pump mechanism, and high average output power and continuum output with high optical conversion efficiency and a wider supercontinuum range can be realized. By the aid of mature high-power fiber laser technology, photonic crystal fiber manufacturing technology and photonic crystal fiber post-treatment technology, system cost is reduced, and industrial production and application are facilitated.

The invention relates to a graphite Raman locked mode laser characterized in that laser gain is provided by a stimulated Raman scattering effect with a flexible wavelength and combined with a graphite Raman locked mode device with a wide saturated absorption band to realize locked mode laser output. The whole device of the graphite Raman locked mode laser is formed by a mechanism of combining a stimulated Raman gain medium with the graphite Raman locked mode device, is compact in structure and convenient to integrate and can be applied to a plurality of fields.

A pulsed cascaded Raman laser (10) includes a pulsed light source (102) for generating a pulsed light (104) having an optical spectrum centered at a source wavelength. A non-linear Raman conversion fiber (106) is coupled to the pulsed light source (102). The pulsed light (104) traverses the nonlinear Raman conversion fiber (106) and the source power at the source wavelength is converted to a power output of an output signal (108) having an output wavelength longer than the source wavelength by a cascaded Stimulated Raman Scattering process, such that most of the source power is converted to the power of the last Stokes order in a single pass through the non-linear Raman conversion fiber (106).

An optically amplified wavelength division multiplexing network has the functionality to add / drop channels at the optical add / drop multiplexing (OADM) nodes. The OADM node includes a receiver amplifier, an OADM module, and a transmitter amplifier. Once the OADM node detects a loss of signal (LOS) due to a fiber cut or network element failure upstream, the receiver amplifier is kept in operation as a noise source. The output of the receiver amplifier is immediately raised by increasing pump power to compensate for the LOS. The noise power received at the transmitter amplifier from the receiver amplifier is substantially equal to the signal power expected before LOS. The transient effect of downstream optical amplifiers is therefore completely suppressed and the inter-channel stimulated Raman scattering (SRS) induced spectrum tilt does not change. After the noise power is raised, the receiver amplifier may be shut down at a speed much slower than the speed of downstream amplifier control circuitry.