Abstract: Integrated active cooling of high-power reflective or diffractive optics uses substrates manufactured from low-expansion ceramics to flow coolant between the back surface of the substrate and chambers behind but adjacent a reflective front surface, in a direction transverse to the front surface, to thereby achieve much greater average power handling than known cooling techniques.

Abstract: Integrated active cooling of high-power reflective or diffractive optics uses substrates manufactured from low-expansion ceramics to flow coolant between the back surface of the substrate and chambers behind but adjacent a reflective front surface, in a direction transverse to the front surface, to thereby achieve much greater average power handling than known cooling techniques.

Abstract: A method, pump and Raman amplifier control an amount of stimulated Brillouin scattering (SBS) produced by the Raman amplifier pump so as to regulate a power penalty experienced by a receiver due to the SBS. A multi-mode semiconductor laser produces a multi-mode pump light having a dominate mode at a predetermined wavelength. At least a portion of the multi-mode pump light is coupled to a Raman gain medium in a forward pumping direction. A reflection sensor monitors reflected light that is at least partially reflected from said Raman gain medium. The reflection sensor has a passband characteristic that passes optical power of a dominate SBS peak of said reflected light, but suppresses other SBS peaks that are offset in wavelength from said dominate SBS peak. The optical power of the dominate SBS peak is compared to an optical power of the multi-mode pump light, and it is determined whether a result of the comparing step is above a predetermined threshold.

Abstract: A method, pump and Raman amplifier control an amount of stimulated Brillouin scattering (SBS) produced by the Raman amplifier pump so as to regulate a power penalty experienced by a receiver due to the SBS. A multi-mode semiconductor laser produces a multi-mode pump light having a dominate mode at a predetermined wavelength. At least a portion of the multi-mode pump light is coupled to a Raman gain medium in a forward pumping direction. A reflection sensor monitors reflected light that is at least partially reflected from said Raman gain medium. The reflection sensor has a passband characteristic that passes optical power of a dominate SBS peak of said reflected light, but suppresses other SBS peaks that are offset in wavelength from said dominate SBS peak. The optical power of the dominate SBS peak is compared to an optical power of the multi-mode pump light, and it is determined whether a result of the comparing step is above a predetermined threshold.

Abstract: Applicants have discovered the existence of loss peaks in optical fiber transmission systems using wavelengths in the E-band and the L-band. Specifically, they have discovered the existence of narrow loss peaks at 1440 nm, 1583 nm and 1614 nm. Because the peaks are relatively narrow, they cannot be easily removed by conventional gain equalizers in long haul transmission systems, and although the peaks are relatively small, they can nonetheless cause transmission channels to drop out in amplified DWDM transmission systems. Applicants have further discovered that these loss peaks are due to carbon contamination of the transmission fiber. Thus optical fibers should be fabricated essentially free of carbon contamination. This means eliminating carbon-containing reagents in preform and tube-making processes.

Abstract: In accordance with the invention, an optical fiber communication system comprising a source of optical signal channels and an optical fiber transmission line is provided with one or more single source, multiple-order Raman pumps downstream of the source. Each single source pump provides multiple-order Raman pump light for amplifying the signal channels.

Abstract: Applicants have discovered the existence of loss peaks in optical fiber transmission systems using wavelengths in the E-band and the L-band. Specifically, they have discovered the existence of narrow loss peaks at 1440 nm, 1583 nm and 1614 nm. Because the peaks are relatively narrow, they cannot be easily removed by conventional gain equalizers in long haul transmission systems, and although the peaks are relatively small, they can nonetheless cause transmission channels to drop out in amplified DWDM transmission systems. Applicants have further discovered that these loss peaks are due to carbon contamination of the transmission fiber. Thus optical fibers should be fabricated essentially free of carbon contamination. This means eliminating carbon-containing reagents in preform and tube-making processes.

Abstract: In accordance with the invention, an optical fiber communication system comprising a source of optical signal channels and an optical fiber transmission line is provided with one or more single source, multiple-order Raman pumps downstream of the source. Each single source pump provides multiple-order Raman pump light for amplifying the signal channels.

Abstract: Dithered-edge sampling (DES) enables ultra-wideband measurement of terahertz pulses (far infrared electromagnetic pulses) using photoconductive antennas. The terahertz pulse is sampled by first passing it through a triggered photoconductive attenuator whose fast attenuation edge (limited only by the duration of the optical gating pulse) is dithered in time. A slow photoconductive receiver then measures the component of the terahertz electric field that is modulated at the dither frequency. The current through the photoconductive element constituting the receiver passes through a locking amplifier which may be operated at dither frequency. When used alone, the receiver blurs the measured terahertz pulse width. However, the increased time resolution provided by DES enables measurement of source-limited terahertz pulse widths. In addition, DES may be used to make direct measurements of a photoconductive receiver's temporal response.