Abstract: The present invention relates to an OPCPA apparatus. The OPCPA of the present invention includes an optical pulse stretcher (100) for outputting chirped laser light using odd-order dispersion (third-order dispersion is mainly used). A pump laser (200) outputs pump laser light. An OPA unit (300) receives the pump laser light and the chirped laser light (signal), amplifies the signal using the pump laser light, and generates an idler. An optical signal separation unit (400) separates output light of the OPA unit into the signal, the idler, and remaining light (pump). An optical pulse compressor (600) compensates for pulse chirping caused by odd-order dispersion that is imparted by the optical pulse stretcher, thus temporally compressing the signal and the idler, which overlap each other.

Abstract: The present invention relates to a device (1, 11) for amplifying light pulses (2, 12), the device comprised of a stretcher (4, 14) which temporally stretches the light pulses (2, 12), and comprised of at least one amplifier (5, 15) which amplifies the stretched light pulses (2, 12), and comprised of a compressor (6, 16) which recompresses the stretched and amplified light pulses (2, 12), the stretcher (4, 14) and the compressor (6, 16) being dispersive elements with essentially oppositely identical dispersion. To provide a device (1, 11) for amplifying light pulses (2, 12) which is of a compact setup and which can be flexibly applied, the present invention proposes that the dispersion of the amplifier (5, 15), the dispersion of further optical elements of the device (1) and/or a mismatch of dispersion of the stretcher (4, 14) and compressor (6, 16) are at least partly compensated by self-phase modulation of the light pulses (2, 12) and/or by at least one additional element (17) of variable dispersion.

Abstract: An optical amplifier includes a first amplification medium to receive light obtained by combining signal light input into an input port and the excitation light generated by a light source; a second amplification medium disposed between the first amplification medium and an output port; a loss medium to receive the signal light separated from light output from the first amplification medium; a variable optical attenuator that is disposed on a path that bypasses the loss medium, and to receive the excitation light separated from the light output from the first amplification medium; a first photodetector to detect power of light separated from the signal light transmitted from the second amplification medium; and a controller to control the amount of attenuation for the variable optical attenuator or output power of the light source so that signal light power per wavelength of the signal light becomes closer to a target value.

Abstract: An optical amplifier amplifies signal light and includes a pump light source that outputs pump light of a wavelength different from that of the signal light; a combining unit that combines the signal light and the pump light output by the pump light source, to output combined light; an amplifying unit that has non-linear optical media that transmit the combined light to amplify the signal light, the amplifying unit further removing, in the non-linear optical media, idler light generated from the signal light and the pump light, and outputting light that results; and an extraction filter that extracts the signal light from the light output by the amplifying unit.

Abstract: A pulse laser apparatus includes a laser configured to generate a pulse of a laser beam, a fiber amplifier, and a pulse compressor. The fiber amplifier includes a rare-earth doped fiber that exhibits normal dispersion at a wavelength of the laser beam generated from the laser. The pulse laser apparatus further includes a unit configured to give a loss to energy portions in a wavelength region corresponding to a zero-dispersion wavelength of the rare-earth doped fiber and/or a wavelength region longer than the zero-dispersion wavelength within a wavelength spectrum of the laser beam having been chirped in the fiber amplifier.

Abstract: A chirped pulse amplification (CPA) system comprises an optical pulse stretcher and an optical pulse compressor that are mismatched in that the optical pulse compressor includes a bulk optical grating while the optical pulse stretcher does not. High order dispersion compensation is provided by an optical phase mask disposed within the optical pulse compressor.

Abstract: A light dispersion filter is composed of three or more optically transparent layers each having a value equal to the value of the product of the refractive index and thickness of the optically transparent layer and transmitted light, and a plurality of partially reflective layers arranged alternately with the optically transparent layers and having predetermined reflectivities. Alternatively, a light dispersion filter has a plurality of etalon resonators which are arranged in series such that the value of the product of the refractive index of air and the interval of the etalon resonators is equal to the value of the product of the refractive index and thickness of the optically transparent layers.

Abstract: A chirped pulse amplification system includes a laser source providing an input laser pulse along an optical path. The input laser pulse is characterized by a first temporal duration. The system also includes a multi-pass pulse stretcher disposed along the optical path. The multi-pass pulse stretcher includes a first set of mirrors operable to receive input light in a first plane and output light in a second plane parallel to the first plane and a first diffraction grating. The pulse stretcher also includes a second set of mirrors operable to receive light diffracted from the first diffraction grating and a second diffraction grating. The pulse stretcher further includes a reflective element operable to reflect light diffracted from the second diffraction grating. The system further includes an amplifier, a pulse compressor, and a passive dispersion compensator disposed along the optical path.

Abstract: An optical amplifier includes a first optical amplification unit that amplifies input light, a variable optical attenuation unit that attenuates an output of the first optical amplification unit, a second optical amplification unit that amplifies an output of the variable optical attenuation unit, and a loss amount control unit that controls the variable optical attenuation unit, wherein an external attenuating optical medium is inserted between the variable optical attenuation unit and the second optical amplification unit. The optical amplifier includes an abnormality detecting unit that detects abnormality in optical loss based on a light level between the external attenuating optical medium and the second optical amplification unit, and a detection invalidating unit that invalidates any abnormality detected by the abnormality detecting unit when a light level between the variable optical attenuation unit and the external attenuating optical medium is lower than a threshold level.

Abstract: A chirped pulse fiber amplifier with nonlinear compensation, includes elements for generating a light pulse having an initial peak-power P0 and an initial duration T, a stretcher including at least one optical diffraction network having a line density higher than 1200 lines/mm and suitable for time-stretching the pulse and of inserting a time asymmetry in the stretched pulse, an amplifying fiber including a doped optical fiber section coupled with an optical pumping element and suitable for amplifying the stretched pulse for producing a pulse having a power, a compressor with optical diffraction grating suitable for time-compressing the amplified pulse so that the stretcher and the compressor are mismatched, the mismatch between the stretcher and the compressor being suitable for simultaneously compensating the second- and third-order nonlinear dispersions in the amplifying fiber during the propagation of a pulse having an initial power P0 through the chirped pulse amplifier.

Abstract: A cascaded optical amplifier including a first optical amplifier and a second optical amplifier in cascaded arrangement is provided. Each of the first optical amplifier and the second optical amplifier has a respective input for receiving an optical signal, an output for outputting an amplified optical signal, and a control input for controlling the gain of the optical amplifier. The cascaded optical amplifier includes a sensor for sensing upstream of the input of the second optical amplier a signal relating to operation of the cascaded optical amplifier. In addition, the cascaded optical amplifier includes a controller for providing control signals to the respective control inputs of the first amplifier and the second amplifier, the controller providing the control signal to the second optical amplifier as a function of the sensed signal.

Abstract: A short pulse fiber laser amplification system includes a special fiber stretcher, managed preamplifier, managed amplifier chain, and managed compressor to control an increase of a passive dispersion by managing a third order dispersion (TOD) to a group velocity dispersion (GVD) ratio for matching a nonlinearity chirp. In an exemplary embodiment, the TOD to GVD ratio is managed between approximately 1.5 to 15 fs to match a nonlinearity in range between 1? to 10?. In another exemplary embodiment, the TOD to GVD ratio is managed between approximately 15 to 705 fs to match a nonlinearity in range between 1? to 50?.

Abstract: The present invention relates to an optical amplifier and the like having a flatter gain spectrum in the wavelength band of 1490 nm to 1520 nm than before. The optical amplifier according to the present invention comprises an Er-doped optical waveguide and a Tm-doped optical waveguide having gain spectra difference from each other in the wavelength band. The signal light entered through the input end is first amplified by the Er-doped optical waveguide, and thereafter is amplified by the Tm-doped optical waveguide. The gain deviation of the amplified signal light, which has been amplified in the Er- and Tm-doped optical waveguides and outputted through the output end, can be reduced over the wavelength band.

Abstract: System and method for dispersion compensation tuning for a WDM optical transmission system. A tunable dispersion compensation module (4) is located at or substantially close to a transmitting end of the optical transmission line (2) and at least one distributed Raman amplifier having an Raman pump (1) is coupled to the transmission line 2. The dispersion compensation is controlled by means of a signal derived from the Raman pump (1) which is fed through a control loop (3) to the tunable dispersion compensation module (4).

Abstract: To compensate a waveform distortion by using a nature that a spectral shape is perfectly retained even if all the linear distortions occur on a time-axis. An optical pulse transmitted from an optical pulse transmitter (1) via an optical fiber transmission line (2) is transmitted. An optical Fourier transformer (3) receives an optical pulse, and optically Fourier-transforms an optical pulse on a time-axis onto a frequency-axis to reproduce the frequency spectrum of an optical pulse on a time-axis be effecting switching between frequency and time, thereby compensating a waveform distortion by a linear effect on the optical fiber transmission line (2). A photodetector (4) receives an optical pulse from the optical Fourier transformer (3) and transforms this into an electrical signal to thereby obtain a pulse waveform before a transmission over the optical fiber transmission line (2).

Abstract: The present invention provides devices and methods for Raman amplification and dispersion compensation. According to one embodiment of the present invention, a dispersion compensating device includes a dispersion compensating fiber having a dispersion more negative than about ?50 ps/nm/km over a wavelength range of about 1555 nm to about 1615 nm; a Raman gain fiber having a dispersion more positive than about ?40 ps/nm/km over a wavelength range of about 1555 nm to about 1615 nm; and a pump source operatively coupled to the dispersion compensating fiber and the Raman gain fiber, the pump source operating at a pump wavelength, wherein the dispersion compensating fiber has a Raman Figure of Merit at the pump wavelength, and wherein the Raman gain fiber has a Raman Figure of Merit at least about equivalent to the Raman Figure of Merit of the dispersion compensating fiber, and wherein the dispersion compensating fiber and the Raman gain fiber are arranged in series between the input and the output of the device.

Abstract: A modular, compact and widely tunable laser system for the efficient generation of high peak and high average power ultrashort pulses. Modularity is ensured by the implementation of interchangeable amplifier components. System compactness is ensured by employing efficient fiber amplifiers, directly or indirectly pumped by diode lasers. Dispersive broadening is introduced by dispersive pulse stretching in the presence of self-phase modulation and gain, resulting in the formation of high-power parabolic pulses. In addition, dispersive broadening is also introduced by simple fiber delay lines or chirped fiber gratings, resulting in a further increase of the energy handling ability of the fiber amplifiers. After amplification, the dispersively stretched pulses can be re-compressed to nearly their bandwidth limit by the implementation of another set of dispersive delay lines.

Abstract: A Raman amplifier according to the present invention comprises a plurality of pumping means using semiconductor lasers of Fabry-Perot, DFB, or DBR type or MOPAs, and pumping lights outputted from the pumping means have different central wavelengths, and interval between the adjacent central wavelength is greater than 6 nm and smaller than 35 nm. An optical repeater according to the present invention comprises the above-mentioned Raman amplifier and adapted to compensate loss in an optical fiber transmission line by the Raman amplifier. In a Raman amplification method according to the present invention, the shorter the central wavelength of the pumping light the higher light power of said pumping light.

Abstract: The present invention relates to a method of amplification based on spatio-temporal frequency drift for a pulse laser comprising a so-called CPA (Chirped Pulse Amplification) frequency-shift amplifying chain, the various spectral components spatially spread. The various components separately amplified.

Abstract: An apparatus for compensating for pixel distortion while reproducing hologram data includes an extraction unit, a determination and calculation unit, a table, and a compensation unit. The extraction unit extracts a reproduced data image from a reproduced image frame including the reproduced data image and borders. The determination and calculation unit determines position values of edges of the extracted reproduced data image, and calculates average magnification error values of pixels within line data from position values of start and end point pixels thereof, which are based on the determined position values of the edges. The table stores misalignment compensation values for the pixels within the line data, wherein the misalignment compensation values correspond to predetermined references for average magnification error values.

Abstract: A chromatic dispersion compensator of present invention includes a high-refractive-index VIPA plate, a three-dimensional mirror, and a control unit. The high-refractive-index VIPA plate is made of a material such as silicon having a refractive index higher than that of optical glass and is able to output incident lights toward different directions according to wavelength. The three-dimensional mirror reflects the light of each wavelength emitted from the high-refractive-index VIPA plate, at a predetermined position and returns the light to the VIPA plate. The control unit controls a temperature of the high-refractive-index VIPA plate at a constant level while controlling the position of the three-dimensional mirror corresponding to a chromatic dispersion compensation amount. Thereby, larger chromatic dispersion can be compensated while a decrease in transmission bandwidth is suppressed.

Abstract: Optical dispersion compensation (ODC) devices are disclosed. In one aspect, an ODC device may include first and second groups of optical resonator devices coupled together to compensate for optical dispersion by collectively delaying light. The first group of optical resonator devices may have a first group delay curve with a convex shape between peaks in frequency. The second group of optical resonator devices may have a second group delay curve with a concave shape at a peak in frequency. The ODC device may also include one or more thermal devices to change the temperature of the first group of optical resonator devices as a group, and one or more additional thermal devices to change the temperature of the second group of optical resonator devices as a group. Methods of making and using the ODC devices are also disclosed, as well as various systems including the ODC devices.

Abstract: The present invention relates to an OPCPA apparatus. The OPCPA of the present invention includes an optical pulse stretcher (100) for outputting chirped laser light using odd-order dispersion (third-order dispersion is mainly used). A pump laser (200) outputs pump laser light. An OPA unit (300) receives the pump laser light and the chirped laser light (signal), amplifies the signal using the pump laser light, and generates an idler. An optical signal separation unit (400) separates output light of the OPA unit into the signal, the idler, and remaining light (pump). An optical pulse compressor (600) compensates for pulse chirping caused by odd-order dispersion that is imparted by the optical pulse stretcher, thus temporally compressing the signal and the idler, which overlap each other.

Abstract: A Gires-Tournois etalon (GTE) (10) comprising an optical fiber (12) in which a primary chirped fiber Bragg grating (FBG) (16) is provided, an RF signal generator (20), a piezoelectric transducer (22), and a glass horn (24), for coupling an acoustic wave (26) into the fiber (12). The acoustic wave (26) causes a periodic compression within the fiber (12), which induces a low frequency periodic refractive index modulation within the grating section (14) of the fiber (12). This causes two side frequency components to be generated for each high-frequency component of the FBG (16). Two secondary grating are thus excited, having the same spectral bandwidth as the FBG (16), but a lower reflectivity and different central wavelengths. The free spectral range of the GTE (10) can be adjusted by varying the frequency of the acoustic wave (26). The reflectivity of the excited secondary gratings can be adjusted by adjusting the amplitude of the acoustic wave (26).

Abstract: Methods, devices and systems for generating ultrashort optical linear chirped pulses with very high power by amplifying the pulses so that their temporal duration is longer than the storage time of the amplifying medium. The additional gain factor is related to the ratio of the storage time to the stretched pulse. A preferred embodiment connects a mode locked laser source that generates optical pulses whose duration is stretched with a chirped fiber Bragg grating. Embodiments include methods, devices and systems causing an extreme chirped pulse amplifier (XCPA) effect in an oscillator.

Abstract: Methods, devices and systems for generating ultrashort optical linear chirped pulses with very high power by amplifying the pulses so that their temporal duration is longer than the storage time of the amplifying medium. The additional gain factor is related to the ratio of the storage time to the stretched pulse. A preferred embodiment connects a mode locked laser source that generates optical pulses whose duration is stretched with a chirped fiber Bragg grating. Embodiments include methods, devices and systems causing an extreme chirped pulse amplifier (XCPA) effect in an oscillator.

Abstract: A method for fabricating a tunable Fabry-Perot cavity comprises etching a substrate to form two reflectors separated by an air gap and an electrostatic mechanism. One of the two reflectors is mobile and connected to the electrostatic mechanism. Therefore, operation of the electrostatic mechanism moves the mobile reflector to change the thickness of the air gap and thereby tune the Fabry-Perot cavity. A tunable Fabry-Perot cavity fabricated with the above method comprises: a substrate; two reflectors formed in the substrate and separated by an air gap having a thickness, wherein one of the two reflectors is mobile; and an electrostatic mechanism formed in the substrate and connected to the mobile reflector. The mobile reflector connected to the electrostatic mechanism is moved upon operation of the electrostatic mechanism to change the thickness of the air gap and thereby tune the Fabry-Perot cavity.

Abstract: In a mirror including a substrate and a dielectric multilayer coating structure formed on the substrate, the multilayer coating structure includes two mirror-function layer portions, each formed by a plurality of Layers deposited one on another, and a cavity layer that is arranged between the two mirror-function layer portions, and which causes light having a predetermined wavelength to resonate between the two mirror-function layer portions. Further, a dispersion value with respect to the light having the predetermined wavelength is in the range of ?600 fs2 to ?3000 fs2 and a reflectance with respect to the light having the predetermined wavelength is in the range of 97% to 99.5%.

Abstract: A light dispersion filter is composed of three or more optically transparent layers each having a value equal to the value of the product of the refractive index and thickness of the optically transparent layer and transmitted light, and a plurality of partially reflective layers arranged alternately with the optically transparent layers and having predetermined reflectivities. Alternatively, a light dispersion filter has a plurality of etalon resonators which are arranged in series such that the value of the product of the refractive index of air and the interval of the etalon resonators is equal to the value of the product of the refractive index and thickness of the optically transparent layers.

Abstract: An all-fiber chirped pulse amplification (CPA) system and method is provided that utilizes a hollow core photonic bandgap fiber as a pulse compressor and a dispersion compensating optical fiber as a pulse stretcher that are matched with respect to both the amount and slope of dispersion to avoid peak power-limiting pulse distortion. The CPA system includes a rare earth ion-doped optical fiber amplifier having an input and an output that amplifies optical pulses having a center wavelength of ?c, a pulse compressing length L1 of hollow core photonic bandgap fiber having a dispersion value D1 and a dispersion slope S1 that varies over a wavelength ? of the pulses that is optically connected to the output of the fiber amplifier and having a k-parameter defined by a ratio of D1 over the slope of the function D1(?) that is larger than about 50, and a pulse stretching length L2 of dispersion compensating optical fiber connected to the input of the fiber amplifier having a dispersion value D2 and dispersion slope S2.

Abstract: There is disclosed an optical fiber wherein an absolute value of the fourth order dispersion ?4 of fourth derivative ?4 of propagation constant ? with respect to angular frequency ? at a mean zero dispersion wavelength ?0 in an overall length is not more than 5×10?56 s4/m and wherein a fluctuation of a zero dispersion wavelength along a longitudinal direction is not more than ±0.6 nm.

Abstract: A fiber Chirped Pulse Amplification (CPA) laser system includes a fiber mode-locking oscillator for generating a laser for projecting to a fiber stretcher for stretching a pulse width of the laser wherein the stretcher further comprising a self-phase modulation (SPM) assisted photonics crystal fiber (PCF) single mode (SM) fiber stretcher. The fiber CPA laser system further includes a multistage amplifier for amplifying the laser and a high-order dispersion-compensating compressor for compensating high order dispersions and compressing the pulse width of the laser.

Abstract: A Gires-Tournois etalon (GTE) (10) comprising an optical fibre (12) in which a primary chirped fibre Bragg grating (FBG) (16) is provided, an RF signal generator (20), a piezoelectric transducer (22), and a glass horn (24), for coupling an acoustic wave (26) into the fibre (12). The acoustic wave (26) causes a periodic compression within the fibre (12), which induces a low frequency periodic refractive index modulation within the grating section (14) of the fibre (12). This causes two side frequency components to be generated for each high-frequency component of the FBG (16). Two secondary grating are thus excited, having the same spectral bandwidth as the FBG (16), but a lower reflectivity and different central wavelengths. The free spectral range of the GTE (10) can be adjusted by varying the frequency of the acoustic wave (26). The reflectivity of the excited secondary gratings can be adjusted by adjusting the amplitude of the acoustic wave (26).

Abstract: It is an object of the present invention to provide a control technique for reducing wavelength dependence of wavelength dispersion values and also for suppressing a change in wavelength transmission characteristic with a temperature variation or the like, in a VIPA-type wavelength dispersion compensator.

Abstract: An optical waveform reshaping device, including a semiconductor optical waveguide which has an active layer, wherein: optical amplification regions and optical absorption regions are installed alternately along the semiconductor optical waveguide; one optical amplification region is set longer than the other optical amplification regions so that a desired amplification factor can be obtained when power of an input optical signal is at an ON level; a power level is maintained by the other optical amplification regions excluding the one optical amplification region and by the optical absorption regions when the power of the input optical signal is at the ON level; and when the power of the input optical signal is at an OFF level, the input optical signal is absorbed by the optical absorption regions so that a power level of an output optical signal will not be higher than the power level of the input optical signal.

Abstract: By compensating polarization mode-dispersion as well chromatic dispersion in photonic crystal fiber pulse compressors, high pulse energies can be obtained from all-fiber chirped pulse amplification systems. By inducing third-order dispersion in fiber amplifiers via self-phase modulation, the third-order chromatic dispersion from bulk grating pulse compressors can be compensated and the pulse quality of hybrid fiber/bulk chirped pulse amplification systems can be improved. Finally, by amplifying positively chirped pulses in negative dispersion fiber amplifiers, low noise wavelength tunable seed source via anti-Stokes frequency shifting can be obtained.

Abstract: The present invention provides devices and methods for Raman amplification and dispersion compensation. According to one embodiment of the present invention, a dispersion compensating device includes a dispersion compensating fiber having a dispersion more negative than about ?50 ps/nm/km over a wavelength range of about 1555 nm to about 1615 nm; a Raman gain fiber having a dispersion more positive than about ?40 ps/nm/km over a wavelength range of about 1555 nm to about 1615 nm; and a pump source operatively coupled to the dispersion compensating fiber and the Raman gain fiber, the pump source operating at a pump wavelength, wherein the dispersion compensating fiber has a Raman Figure of Merit at the pump wavelength, and wherein the Raman gain fiber has a Raman Figure of Merit at least about equivalent to the Raman Figure of Merit of the dispersion compensating fiber, and wherein the dispersion compensating fiber and the Raman gain fiber are arranged in series between the input and the output of the device.

Abstract: There is provided an optical amplifier including a Raman amplification medium, a rare earth doped fiber located at a latter stage of the Raman amplification medium, a first pump light outputting unit for outputting pump light with a plurality of wavelengths, a variable distribution element for distributing the pump light with the plurality of wavelengths, outputted from the first pump light outputting unit, to the Raman amplification medium and the rare earth doped fiber in a variable distribution ratio for each wavelength, and a control unit for individually controlling the distribution ratio of the pump light with the plurality of wavelengths in the variable distribution element and the power of the pump light with the plurality of wavelengths from the first pump light outputting unit in accordance with a wavelength arrangement of each of signal lights wavelength-multiplexed into the wavelength-multiplexed signal light.

Abstract: Reducing polarization dependence of a dispersion variation monitor includes receiving an optical signal. The optical signal is split into a first polarized signal having first photons and a second polarized signal having second photons. The first photons are received at a first material of a first detector, where the first material is operable to produce a reaction in response to the arrival of a predetermined number of photons. The second photons are received at a second material of a second detector, where the second material is substantially similar to the first material. A first current produced by the first material in response to receiving the first photons and a second current produced by the second material in response to receiving the second photons are monitored. Whether there is wavelength dispersion variation among the plurality of components is established in accordance with the first current and the second current.

Abstract: A chromatic dispersion compensator whereby the amount of dispersion and the group delay time can be easily adjusted. A dispersion unit, a transmitting lens and a group delay generation unit are arranged along the optical axis of incident light. The dispersion unit separates the incident light into beams of respective different wavelengths. The transmitting lens is arranged across the optical paths of the beams of different wavelengths separated by the dispersion unit, and refracts the beams at different angles according to their respective incidence positions. The group delay generation unit is arranged across the optical paths of the beams of different wavelengths refracted by the transmitting lens, causes the beams to undergo propagation delay for periods corresponding to their respective incidence positions, and converges and emits the beams of different wavelengths. Consequently, the beams of different wavelengths are imparted group delay corresponding to the refracting angles of the transmitting lens.

Abstract: The invention is the novel use of dispersion compensation in a long haul wavelength division multiplexed high capacity optical transport system which has very many channels packed extremely closely together, in order to greatly reduce the deleterious effects of four-wave mixing. Four-wave mixing is an exchange of energy between nominally independent channels, arising from the fundamental fiber non-linearity, which has the effect of degrading transmission quality. Conventional systems make use of fiber dispersion compensating modules to overcome the effects of fiber dispersion. In such systems, it has been discovered that the exact distribution of fiber dispersion along the optical link (the ‘dispersion map’) strongly influences the degree of four-wave mixing, and hence the degradation in transmission quality.

Abstract: One embodiment of an optical interferometer includes a first MMI device coupled to a second MMI device via a waveguide. The first MMI device separates a first signal into a guided portion and a diffused portion. The guided portion is transmitted to the second MMI device through the waveguide. At least part of the diffused portion reflects off a reflector towards the second MMI device and is coupled with the guided portion within either the second MMI device or a part of the waveguide proximal to the second MMI device, forming at least part of a second signal. The difference between the propagation times of the guided portion and the at least part of the diffused portion results in constructive or destructive interference between the two portions, allowing specific channels to be added to or dropped from the first signal.

Abstract: A device for amplifying light pulses has an optical stretcher, in which the light pulses of a pulsed laser light source are temporally stretched, and an optically pumped amplifier fiber, in which the light pulses are amplified and, at the same time, temporally compressed. In order to improve such a system with regard to the pulse duration and the pulse energy that can be achieved, the amplifier fiber has a positive group velocity dispersion, whereby the amplifier fiber has non-linear optical properties, so that the optical spectrum of the light pulses is broadened during the amplification process, taking advantage of non-linear self-phase modulation.

Abstract: An optical dispersion compensator including: a spacer element having a top surface and a bottom surface; a thin film, multi-layer mirror formed on the top surface of the spacer element, the thin film mirror having a thermally tunable reflectivity; a highly reflective mirror element formed on the bottom surface of the spacer element; and a heater element for controlling a temperature of the thermally tunable thin film mirror.

Abstract: A device for generating tunable light pulses has a non-linear optical fiber. The optical spectrum of femtosecond light pulses can be modified by this optical fiber, taking advantage of solitonic effects. In order to make available such a device, which makes it possible to vary the pulse energy and the wavelength of the light pulses independently of one another, an optical compressor precedes the non-linear optical fiber.

Abstract: Optical amplifier which can eliminate the need for an optical detection section before an external attenuating medium, can prevent SN degradation, and can reduce power required for pumping light. An attenuation amount detection section detects an amount of signal light attenuation caused by a variable optical attenuator and the external attenuating medium connected in series, by means of a front optical detection section provided before the variable optical attenuator and the external attenuating medium and a back optical detection section provided thereafter. An attenuation amount control section controls the variable optical attenuator such that the amount of signal light attenuation detected by the attenuation amount detection section is kept constant. A connection detection section detects a connection or disconnection of the external attenuating medium in accordance with the amount of signal light attenuation obtained when the amount of attenuation caused by the variable optical attenuator is minimized.

Abstract: A wavelength-division multiplexing optical transmission system for providing a compensating-purpose dispersion D2 to a wavelength-division multiplexing optical signal to be transmitted through an optical transmission path from a transmitter terminal to a receiver terminal. The compensating-purpose dispersion D2 satisfies conditions that at any wavelength “?” included in the transmission wavelength band, if dD1(?)/d??0 is established, then {dD1(?)/d?}×{dD2(?)/d?}<0 is also established, and if dD1(?)/d?=0 is established, then dD2(?)/d?=0 is also established, where D1 represents a dispersion generated in the wavelength-division multiplexing optical signal during when the wavelength-division multiplexing optical signal is transmitted through the transmission path from the transmitter terminal to the receiver terminal.

Abstract: A method to improve an extinction ratio of an optical device, the method includes positioning at least a majority of a plurality of micro-mirrors in an off-state position. A mirror assembly includes the plurality of micro-mirrors. The method also includes selectively positioning at least one of the plurality of micro-mirrors in an on-state position. In one particular embodiment, the at least one of the plurality of micro-mirrors positioned in the on-state position operates to improve an extinction ratio of an optical device.

Abstract: A modular, compact and widely tunable laser system for the efficient generation of high peak and high average power ultrashort pulses. Modularity is ensured by the implementation of interchangeable amplifier components. System compactness is ensured by employing efficient fiber amplifiers, directly or indirectly pumped by diode lasers. Peak power handling capability of the fiber amplifiers is expanded by using optimized pulse shapes, as well as dispersively broadened pulses. Dispersive broadening is introduced by dispersive pulse stretching in the presence of self-phase modulation and gain, resulting in the formation of high-power parabolic pulses. In addition, dispersive broadening is also introduced by simple fiber delay lines or chirped fiber gratings, resulting in a further increase of the energy handling ability of the fiber amplifiers.

Abstract: A method of compensating for chromatic dispersion in an optical signal transmitted on a long-haul terrestrial optical communication system including a plurality of spans, including: allowing chromatic dispersion to accumulate over at least one of the spans to a first predetermined level; and compensating for the first pre-determined level of dispersion using a dispersion compensating fiber causing accumulation of dispersion to a second predetermined level. There is also provided a hybrid Raman/EDFA amplifier including a Raman portion and an EDFA portion with a dispersion compensating fiber disposed therebetween. An optical communication system and a method of communicating an optical signal using such a Raman/EDFA amplifier are also provided.