Abstract: Several examples of double-pass fiber amplifiers including a polarization maintaining (PM) gain-fiber are disclosed. In each example, input and twice-amplified output are separated by an all-fiber, polarization-maintaining polarization splitter combiner. The examples include double-pass fiber amplifiers not including any bulk components and double pass fiber amplifiers including a bulk component or a Faraday rotating mirror located in a position in the amplifier wherein the component is exposed only to radiation amplified on the first pass through the gain-fiber.

Abstract: This invention consists of an optical external cavity having specialized Brewster angle wedges. The external cavity apparatus utilizes several types of very high index of refraction wedges made from semiconductor and special glass materials. The apparatus limits the oscillation of the optical wavelength modes emitted by a diode laser. In addition, such cavities also simplify the motions of the moveable mirror that returns these selected laser photons to the cavity input beam path or fiber. The wedge also disperses the laser light to isolate the desired wavelength band better than the currently used grating systems. Wavelengths other than the desired wavelength band are dispersed, then reflected at angle away from the return fiber and thus not returned to the amplification cavity inside the laser. The apparatus then emits only the laser photon mode desired by the user.

Abstract: A small size and high efficiency laser oscillation apparatus capable of obtaining high output and high beam quality laser light is provided. First waveguide (21) (refractive index=n1) for transmitting excitation light, second waveguide (22) composed of core (23) (refractive index=n3) for generating laser light and clad (24) (refractive index=n2) for transmitting the excitation light, and third waveguide (25) (refractive index=n4) including first waveguide 21 and second waveguide 22 are provided. Light amplifying fiber (20), in which the refractive indices are set so as to satisfy the relation: n1<n4<n2<n3, is used and excised by semiconductor lasers (10a) and (10b).

Abstract: A semiconductor device, comprising a semiconductor stacking body configured so as to sandwich an active layer by a p-type semiconductor layer and an n-type semiconductor layer and having plural regions along the active layer, plural electrodes provided on the p-type semiconductor layer or the n-type semiconductor layer and provided one for each of the plural regions, and a switch operatively connected to at least one of the plural electrodes for switching bias voltage application directions, is configured such that each of the plural regions is forward biased by a voltage applied via the electrode and becomes an amplification region when the switch is turned to one side, and is backward biased by a voltage applied via the electrode and becomes an attenuation region when the switch is turned to the other side.

Abstract: Provided is an apparatus and method for simultaneous optical wavelength conversion and optical clock signal extraction using semiconductor optical amplifiers (SOAs).

Abstract: An optical transmission system having a supervisory system of devices disposed along an optical link. Counter-propagating Raman amplifiers are disposed along the optical link. Low-frequency supervisory signals are superimposed on the optical signals traveling on the optical link by suitable modulators in the devices disposed along the line. Counter-propagating Raman amplifiers amplify optical signals and do not introduce a substantial amount of attenuation on the low-frequency supervisory signals.

Abstract: A communication system for distributed Raman amplification of optical signals is disclosed. The communication system comprises a first fiber span, a second fiber span, and an amplifier system. The amplifier system generates a light beam and splits the light beam into a first portion and a second portion. The amplifier system transfers the first portion of the light beam onto the first fiber span so that the first portion of the light beam backward propagates over the first fiber span. The amplifier system transfers the second portion of the light beam onto the second fiber span so that the second portion of the light beam forward propagates over the second fiber span.

Abstract: An optical amplifier includes a first optical path, second optical path, semiconductor optical amplifier, and multi-mode interference 3-dB coupler. The first optical path guides oscillation light. The second optical path guides signal light. The semiconductor optical amplifier causes oscillation on the first optical path. The multi-mode interference 3-dB coupler crosses the first and optical paths in the gain medium of the semiconductor optical amplifier.

Abstract: The present invention provides a protective device for sensitive infrared sensors as Forward Looking Infrared imagers (FLIRs). A prior device using materials with higher order susceptibilities to electric polarization, which provides protection against extremely intense radiation from high-power lasers is combined with a low energy optical power limiters such as the chalcogenide glass and the vanadium dioxide which respond reversibly to infrared radiation.

Abstract: In an optical amplifying device, an optical beam passes multiple times through a grazing-incidence bounce amplifier, accessing different parts (G1,G2) of the gain region on each transit. This provides improved characteristics in beam quality, with higher power scalability. The multipass configuration can operate as a high gain amplifier device and, with the addition of suitable feedback such as reflectors (M1-M4), as a laser oscillator to provide an optical source.

Abstract: An optical transmission system having a supervisory system of devices disposed along an optical link. Co-propagating Raman amplifiers are disposed along the optical link. Low frequency supervisory signals are superimposed on the optical signals traveling on the optical link by suitable modulators in the devices disposed along the line or by the same co-propagating Raman amplifiers. Regeneration of the supervisory signal is provided in at least one device disposed along the optical link in order to counteract attenuation introduced on the supervisory signal by the co-propagating Raman amplifiers.

Abstract: In an optical transmission system, operations of certain elements are adjusted in an individualized manner after detecting a change in the total optical power level corresponding to multiple optical channels in a link of the system in order to control transients in those channels. For example, in response to a sudden drop in the number of channels resulting from a fiber cut, the power levels of the optical pumps in a Raman amplifier in an OADM are adjusted to reduce transient gain errors in the surviving channels, where the adjustment to the pump power level for each different optical pump is a function of both the detected change in the total optical power level and at least one specified coefficient for that particular optical pump, in order to handle non-linearities in the response of the Raman amplifier to the sudden drop in the number of optical channels.

Abstract: Systems and methods for transmitting quantum and classical signals over an optical network are disclosed, wherein the quantum signal wavelength either falls within the classical signal wavelength band, or is very close to one of the classical signal wavelengths. The system includes a deep-notch optical filter with a blocking bandwidth that includes the quantum signal wavelength but not any of the classical signal wavelengths. The deep-notch optical filtering is applied to the classical signals prior to their being multiplexed with the quantum signals to prevent noise generated by the classical signals from adversely affecting transmission of quantum signals in the transmission optical fiber. Narrow-band filtering is also applied to the quantum signals prior to their detection in order to substantially exclude spurious non-quantum-signal wavelengths that arise from non-linear effects in the optical fiber.

Abstract: The invention relates to a method and device for determining the gain spectrum of a Raman amplifier having an optical amplifier, which is connected in incoming circuit thereto, in a section of a WDM transmission system. A number of spectra are recorded at the output of the Raman amplifier during which the optical amplifier or the Raman amplifier is switched on and off and a high amplified spontaneous emission is generated at the input of the Raman amplifier. Afterwards, the gain spectrum is determined on the basis of the recorded spectra.

Abstract: In an optical amplifier, passively wavelength-stabilized pump diodes generate pumping light to excite a gain medium (e.g., rare-earth-ion doped optical fiber or solid-state optical amplifier) near an absorption peak of the gain medium. The gain medium amplifies a pulsed laser signal coupled into the gain medium to a high peak power with minimal non-linear distortion. The gain medium may include a portion configured to receive the pumping light and another portion configured to amplify the pulsed laser signal. A volume phase hologram device may passively wavelength stabilize the pump diodes by reflecting a portion of the pumping light back to the pump diodes. Passively wavelength-stabilizing the pump diodes improves power efficiency of the optical amplifier.

Abstract: A device amplifies light at wavelengths in the vicinity of 1420-1530 nm, using thulium doped silica-based optical fiber. This wavelength band is of interest as it falls in the low-loss optical fiber telecommunications window, and is somewhat shorter in wavelength than the currently standard erbium doped silica fiber amplifier. The device thus extends the band of wavelengths which can be supported for long-distance telecommunications. The additional wavelength band allows the data transmission rate to be substantially increased via wavelength division multiplexing (WDM), with minimal modification to the standard equipment currently used for WDM systems. The host glass is directly compatible with standard silica-based telecommunications fiber. The invention also enables modified silicate based amplifiers and lasers on a variety of alternative transitions. Specifically, an S-band thulium doped fiber amplifier (TDFA) using a true silicate fiber host is described.

Abstract: A fiber amplifier system and method are provided for reducing noise produced by a fiber amplifier by combining an optical signal to be amplified with a continuous wave optical signal that stimulates ions in the fiber amplifier to reduce photons produced by spontaneous emission when a level of the optical signal of interest is very low or zero.

Abstract: A Raman amplification repeater using the amplification function of a signal light caused by Raman scattering which occurs when a pumping light is applied to a transmission path fiber, in which signal light power is monitored by means of a plurality of PDs by using wavelengths for monitoring whose number is larger than the number of pumping light wavelengths to control output power of a pumping light LD which emits the pumping light.

Abstract: Erbium doped fiber amplifiers for dense wavelength division multiplexed (DWDM) metro area optical networks may be configured as either high gain amplifiers or power amplifiers. The erbium doped fiber type, length, and pump power level are selected so that the shape of the gain spectra is approximately the same for single channel or multi-channel operation. In one embodiment, the same erbium doped fiber type and length is used for both power amplifiers and high gain amplifiers, reducing manufacturing costs.

Abstract: Apparatus and method for spectral-beam combining light from a plurality of high-power fiber lasers that, in some embodiments, use two substantially identical diffraction gratings in a parallel, mutually compensating configuration to combine a plurality of separate parallel input beams each having a slightly different successively higher wavelength into a single output beam of high quality. In other embodiments, a single diffraction grating is used to combine a plurality of different wavelengths, wherein the input laser beams are obtained from very narrow linewidth sources to reduce chromatic dispersion. In some embodiments, diagnostics and adjustments of wavelengths and/or positions and angles are made dynamically in real time to maintain the combination of the plurality input beams into a single high-quality output beam.