Abstract: A laser apparatus is disclosed combining polarized light beams from two optical emitters into a combined beam of light with controllable degree of polarization (DoP). The laser apparatus includes a polarization combiner for combining the polarized beams into the combined beam, an optical tap for separating out a portion of the combined beam, and a photodetector electrically coupled to a laser controller for providing a feedback signal. The controller distinctively modulates the polarized radiation of each of the emitters, detects modulation signals in the photodetector output and adjusts an output power ratio of the optical emitters for maintaining the DoP of the combined beam at a pre-determined level. The invention can be used for minimizing the DoP of pump radiation in Raman and EDFA pump laser modules combining multiple pump laser diodes.

Abstract: A laser apparatus is disclosed combining polarized light beams from two optical emitters into a combined beam of light with controllable degree of polarization (DoP). The laser apparatus includes a polarization combiner for combining the polarized beams into the combined beam, an optical tap for separating out a portion of the combined beam, and a photodetector electrically coupled to a laser controller for providing a feedback signal. The controller distinctively modulates the polarized radiation of each of the emitters, detects modulation signals in the photodetector output and adjusts an output power ratio of the optical emitters for maintaining the DoP of the combined beam at a pre-determined level. The invention can be used for minimizing the DoP of pump radiation in Raman and EDFA pump laser modules combining multiple pump laser diodes.

Abstract: Methods and apparatus for coupling of pump light inside a laser cavity of a fiber laser. The optical elements of the cladding pumped laser are configured such that the pump laser is coupled within the laser cavity. An optical fiber laser includes a laser cavity comprising a lasing medium and first and second reflector devices, a pump source, and a combiner. The combiner has a first side, a second side and an input port that may be associated with one of the first and second sides. An output of the pump source is operatively coupled to the input port of the combiner, and the combiner is coupled at its first and second sides within the laser cavity.

Abstract: An apparatus for measuring chromatic dispersion in a waveguide uses a probe signal and a modulated pump signal which are coupled together into a waveguide. The modulated pump signal causes spatial and temporal Raman gain modulation of the probe signal. The amplitude of the pump signal is modulated and the frequency response of the probe signal at the output end of the waveguide is measured. The chromatic dispersion of the waveguide at a given wavelength is determined from the measurements. The probe signal is provided by a CW laser or corresponds to the ASE generated by the pump signal.

Abstract: Fiber-based dispersion compensation elements are provided for use in optical amplifiers and other optical network equipment that handle optical data signals in fiber-optic communications links. The dispersion compensation elements may include chirped superstructure fiber gratings. Systems and method for fabricating the dispersion compensation elements using ultraviolet light are provided.

Abstract: Methods and apparatus for coupling of pump light inside a laser cavity of a fiber laser. The optical elements of the cladding pumped laser are configured such that the pump laser is coupled within the laser cavity. An optical fiber laser includes a laser cavity comprising a lasing medium and first and second reflector devices, a pump source, and a combiner. The combiner has a first side, a second side and an input port that may be associated with one of the first and second sides. An output of the pump source is operatively coupled to the input port of the combiner, and the combiner is coupled at its first and second sides within the laser cavity.

Abstract: An apparatus for measuring chromatic dispersion in a waveguide uses a probe signal and a modulated pump signal which are coupled together into a waveguide. The modulated pump signal causes spatial and temporal Raman gain modulation of the probe signal. The amplitude of the pump signal is modulated and the frequency response of the probe signal at the output end of the waveguide is measured. The chromatic dispersion of the waveguide at a given wavelength is determined from the measurements. The probe signal is provided by a CW laser or corresponds to the ASE generated by the pump signal.

Abstract: Optical channel monitor depolarizers are provided. The depolarizers may be used to reduce the effects of polarization-dependent loss on optical channel power measurements made in optical amplifiers or other optical network equipment. The channel power measurements may be used in controlling optical amplifiers and other equipment in wavelength-division-multiplexing communications links.

Abstract: Optical amplifiers are provided in which optical gain is produced by Raman pumping fiber. The Raman-pumped fiber may be a span of transmission fiber or a coil of fiber in a discrete amplifier. Raman pump light may be provided using laser diodes operating at different wavelengths. The Raman pump light that is produced by the laser diodes may be modulated to reduce pump interactions in the fiber. Raman pump light may be modulated by directly modulating the laser diodes or by using optical components that modulate constant power pump light from the laser diodes.

Abstract: Raman fiber amplifiers are provided in which multiple pump wavelengths are used. A Raman fiber amplifier may be used to amplify optical signal channels over a range of wavelengths. Some of the pump wavelengths may be selected to create Raman gain in this range. Other pump wavelengths may be selected to create Raman loss in this range. Different pump powers may be used at each pump wavelength.

Abstract: An endoscope for image acquisition via illumination of an object's image, such as but not limited to a bar code, by a set of spatially resolved patterns, with subsequent reconstruction of the image without detailed spatial resolution. A device to stabilize the prescribed set of illuminating patterns against bending of the fiber is also disclosed, which consists of the auxiliary pre-bent part of the fiber and the work part of the fiber, subject to the inevitable bends with or without additional compensation. The distorting influence of the bending of the work part is compensated by the controllable loosening of the pre-bent part of the fiber. Encoding of the pixels of the image or of the illumination patterns encodes the intensity of each pixel to the excitation intensity of the corresponding mode. Such encoding is stable to the bending of the guide.