Abstract: A Raman amplifier apparatus includes an optical transmission line with an input to receive an optical signal, an output that passes the optical signal, a first Raman gain fiber and a second Raman gain fiber. A first WDM is positioned between the second Raman gain fiber and the output. A first set of pump wavelengths is input to the first WDM. A second WDM is positioned between the first and second Raman gain fibers. A second set of pump wavelengths is input to the second WDM. At least a portion of the first set of pump wavelengths are different than the second set of pump wavelengths. The first and second set of pump wavelengths propagate in the same direction.

Abstract: A Raman amplifier assembly includes a Raman amplifier configured to receive a signal from a signal source. The signal travels in an upstream direction in the Raman amplifier. A first pump source is coupled to the Raman amplifier. The first pump source produces a first pump beam that travels in a downstream direction and is counter-propagating relative to the signal. A second pump source is coupled to the Raman amplifier and produces a second pump beam that travels in the upstream direction. The second pump source has an average relative intensity noise of less than −80 dB/Hz.

Abstract: An in-line broadband amplifier includes at least one input fiber and a WDM splitter coupled to the input fiber. The splitter splits an optical signal into at least a first wavelength and a second wavelength. A transition from a stop band to a pass band of the splitter occurs in 20 nm or less. A Raman amplifier and a rare-earth doped optical amplifier are coupled to the splitter. A WDM combiner is coupled to the Raman amplifier and the rare-earth doped optical amplifier. The WDM combiner combines an optical signal into at least a first wavelength and a second wavelength. A transition from a stop band to a pass band of the combiner occurs in 20 nm or less. An output fiber is coupled to the WDM combiner.

Abstract: An optical switch element is described, which includes a fixed layer disposed outwardly from a substrate and a movable mirror assembly disposed outwardly from the fixed layer. The moveable mirror assembly is operable to move relative to the fixed layer responsive to a voltage applied to the movable mirror assembly. In a particular embodiment, the movable mirror assembly includes an inner strip spaced apart from the fixed layer by a first distance and an outer strip disposed approximately adjacent to the inner strip and spaced apart from the fixed layer by a second distance which is greater than the first distance. The optical transmission of the optical switch element changes depending on the position of the movable mirror assembly.

Abstract: One aspect of the invention relates to an optical signal processing device including a Mach-Zehnder interferometer which includes a reference arm comprising a first Fabry Perot interferometer and a sample arm comprising a second Fabry Perot interferometer including at least two mirrors forming a Fabry-Perot cavity therebetween, and an adsorbing material disposed within the cavity. The Fabry-Perot interferometer in the sample arm permits a first portion of an input signal to pass multiple times through the sample while a second portion of the input signal passes through the reference arm, and the first and second signal portions are combined at an output to result in constructive or destructive interference between the signal portions.

Abstract: Method and system are disclosed for stable, multi-wavelength continuous wave (CW) generation using fiber-based supercontinuum and spectrum-slicing of its longitudinal modes. The continuum generated is coherent and stable, making it an attractive alternative as a spectrally-sliced source for continuous, multiple wavelength channels. A 140 nm wide supercontinuum with a 10 GHz repetition rate is generated in <30 meters of fiber. To obtain CW channels with 40 GHz spacing, time-domain multiplexing and longitudinal mode slicing are utilized. To obtain stable, continuous wave operation, short-fiber supercontinuum generation and a pulse interleaving method are utilized. The invention may be utilized as a broadband wavelength-division multiplexed source.

Abstract: An amplified broadband optical signal is produced in a transmission system. An optical signal is divided into a first beam and a second beam. The first beam has a wavelength less than a predetermined wavelength. The second beam has a wavelength greater than the predetermined wavelength. The first beam is directed to a transmission link in the transmission system. The transmission system includes a distributed Raman amplifier. The distributed Raman amplifier operates in the wavelength range less than 1480 nm. The second beam is directed to a second amplifier. The first and second beams are combined. An amplified broadband optical signal is produced.

Abstract: An optical switch element is described, which includes a fixed layer disposed outwardly from a substrate and a movable mirror assembly disposed outwardly from the fixed layer. The moveable mirror assembly is operable to move relative to the fixed layer responsive to a voltage applied to the movable mirror assembly. In a particular embodiment, the movable mirror assembly includes an inner strip spaced apart from the fixed layer by a first distance and an outer strip disposed approximately adjacent to the inner strip and spaced apart from the fixed layer by a second distance which is greater than the first distance. The optical transmission of the optical switch element changes depending on the position of the movable mirror assembly.

Abstract: A Raman amplifier assembly includes a Raman amplifier configured to receive a signal from a signal source. The signal travels in an upstream direction in the Raman amplifier. A first pump source is coupled to the Raman amplifier. The first pump source produces a first pump beam that travels in a downstream direction and is counter-propagating relative to the signal. A second pump source is coupled to the Raman amplifier and produces a second pump beam that travels in the upstream direction. The second pump source has an average relative intensity noise of less than −80 dB/Hz.

Abstract: One aspect of the invention includes an optical amplifier operable to amplify a plurality of optical wavelength signals at least in part through Raman amplification. The amplifier includes an input operable to receive a plurality of wavelength signals and an output operable to communicate an amplified version of at least some of the plurality of wavelength signals. The amplifier further includes a pump assembly operable to generate one or more pump signals and a gain medium operable to receive the plurality of wavelength signals and the one or more pump signals and to facilitate amplification of at least some of the plurality of wavelength signals. The amplifier has associated with it a noise figure having a shape varying as a function of wavelength. At least one of the one or more pump signals is operable to have its power varied to selectively control the shape of the noise figure.

Abstract: A method of broadband amplification divides an optical signal of wavelength of 1430 nm to 1620 nm at a preselected wavelength into a first beam and a second beam. The first beam is directed to at least one optical amplifier and produces an amplified first beam. The second beam is directed to at least one rare earth doped fiber amplifier to produce an amplified second beam. The first and second amplified beams are combined.

Abstract: A Raman amplifier apparatus includes an optical transmission line with an input to receive an optical signal, an output that passes the optical signal, a first Raman gain fiber and a second Raman gain fiber. A first WDM is positioned between the second Raman gain fiber and the output. A first set of pump wavelengths is input to the first WDM. A second WDM is positioned between the first and second Raman gain fibers. A second set of pump wavelengths is input to the second WDM. At least a portion of the first set of pump wavelengths are different than the second set of pump wavelengths. The first and second set of pump wavelengths propagate in the same direction.

Abstract: A multi-stage Raman amplifier includes a first Raman amplifier stage having a first sloped gain profile operable to amplify a plurality of signal wavelengths, and a second Raman amplifier stage having a second sloped gain profile operable to amplify at least most of the plurality of signal wavelengths after those wavelengths have been amplified by the first stage. The second sloped gain profile is approximately complementary slope to the slope of the first sloped gain profile. The combined effect of the first and second Raman stages contributes to an approximately flat overall gain profile over the plurality of signal wavelengths.

Abstract: In one embodiment, a Raman oscillator includes at least one laser cavity and a distributed gain fiber positioned in the at least one laser cavity having a single spatial mode over a pumping wavelength to a signal wavelength. The oscillator also includes a coupler adapted to be coupled to a pumping mechanism to pump the distributed gain fiber at the pumping wavelength to obtain an optical signal wherein distributed gain is provided by Raman amplification over at least one cascade order corresponding to the pumping wavelength. A filter is positioned in the at least one laser cavity and has at least one pass band with a transmission peak placed approximately at the at least one cascade order to filter the optical signal to obtain a filtered optical signal having the signal wavelength. The filter has a substantially continuous sinusoidal filter function over at least one period of the filter function.

Abstract: A method and system are disclosed for generating a broadband spectral continuum using short spans of constant-dispersion, dispersion-shifted fibers. The continuum generation results from the combined effects of pulse compression and spectral shaping. Pulse compression is achieved through soliton-effect compression in one or more stages of anomalous dispersion fiber, which lengths are determined by the occurrence of the first optimal compression of the corresponding order of soliton. The spectral shape results from 3rd order dispersion effects on the evolution of the pulse shape as it propagates through the final segment(s) of the fiber span. The pulse area of the incident pulse determines the fiber properties required to optimize compression. The sign and magnitudes of the 2nd and 3rd order dispersions in the final span(s) as well as the pulse width at the input to the final span determine the continuum extent, flatness and symmetry.

Abstract: In one aspect of the invention, a method of amplifying optical signals includes identifying one of a plurality of pump signals driving an amplification system as a failing pump signal comprising a reduced power compared to a normal power of the failing pump signal. The method further includes adjusting the power of at least one other of the plurality of pump signals based at least in part on the failing pump signal to at least partially compensate for a degradation of performance of the amplification system that would otherwise be caused by the reduction in power of the failing pump signal.

Abstract: A multi-stage Raman amplifier includes a first Raman amplifier stage having a first sloped gain profile operable to amplify a plurality of signal wavelengths, and a second Raman amplifier stage having a second sloped gain profile operable to amplify at least most of the plurality of signal wavelengths after those wavelengths have been amplified by the first stage. The second sloped gain profile is approximately complementary slope to the slope of the first sloped gain profile. The combined effect of the first and second Raman stages contributes to an approximately flat overall gain profile over the plurality of signal wavelengths.

Abstract: This invention describes new developments in Sagnac Raman amplifiers and cascade lasers to improve their performance. The Raman amplifier bandwidth is broadened by using a broadband pump or by combining a cladding-pumped fiber laser with the Sagnac Raman cavity. The broader bandwidth is also obtained by eliminating the need for polarization controllers in the Sagnac cavity by using an all polarization maintaining configuration, or at least using loop mirrors that maintain polarization. The polarization maintaining cavities have the added benefit of being environmentally stable and appropriate for turn-key operation. The noise arising from sources such as double Rayleigh scattering is reduced by using the Sagnac cavity in combination with a polarization diversity pumping scheme, where the pump is split along two axes of the fiber. This also leads to gain for the signal that is independent of the signal polarization.

Abstract: A Raman amplifier includes a Raman gain fiber comprising a length of high-dispersion gain fiber and operable to receive at least one optical signal. The Raman amplifier also includes at least one pump source capable of generating at least one pump signal that co-propagates within the Raman gain fiber with at least a portion of the at least one optical signal received by the Raman gain fiber. The length of the high-dispersion gain fiber is at least ten (10) times a walk off length between the at least one pump signal and at least one wavelength of the at least one optical signal received by the Raman gain fiber. In addition, the length of high-dispersion gain fiber is at least two (2) times a walk off length between at least two optical signal wavelengths of the at least one optical signal received by the Raman gain fiber.

Abstract: This invention describes new developments in Sagnac Raman amplifiers and cascade lasers to improve their performance. The Raman amplifier bandwidth is broadened by using a broadband pump or by combining a cladding-pumped fiber laser with the Sagnac Raman cavity. The broader bandwidth is also obtained by eliminating the need for polarization controllers in the Sagnac cavity by using an all polarization maintaining configuration, or at least using loop mirrors that maintain polarization. The polarization maintaining cavities have the added benefit of being environmentally stable and appropriate for turn-key operation. The noise arising from sources such as double Rayleigh scattering is reduced by using the Sagnac cavity in combination with a polarization diversity pumping scheme, where the pump is split along two axes of the fiber. This also leads to gain for the signal that is independent of the signal polarization.