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 broadband fiber transmission system includes a transmission line with at least one zero dispersion wavelength &lgr;o and transmits an optical signal of &lgr;. The transmission line includes a distributed Raman amplifier that amplifies the optical signal through Raman gain. One or more semiconductor lasers are included and operated at wavelengths &lgr;p for generating a pump light to pump the Raman amplifier. A is close to &lgr; and &lgr;0 is less than 1540 nm or greater than 1560 nm.

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 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: 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 amplifier apparatus includes an optical transmission line with a Raman amplification region that provides a pump to signal power conversion efficiency of at least 20%. The Raman amplification region is configured to amplify a signal with multiple wavelengths over at least a 30 nm range of wavelengths. A pump source is coupled to the optical transmission line. An input optical signal is amplified in the Raman amplification region and an output signal is generated that has at least 100 mW more power than the input optical signal.

Abstract: The present invention provides a structure for Raman amplification of signals with counter-propagation of signal and pump and wavelength control while permitting broad bandwidth within each Raman order. The broadband optical amplifier of the invention combines Raman amplification with a circulator loop cavity and/or chirped Bragg gratings to achieve bandwidth performance improvements. The beneficial properties of the circulator loop cavity and/or chirped Bragg gratings can also combined with noise dampening property of the Sagnac Raman cavity.

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 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: 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: Disclosed is an all waveguide fiber wavelength converter which makes use of modulational instability to convert signal wavelength over a conversion bandwidth while maintaining low pump laser power relative to other wavelength conversion devices such as those which make use of four wave mixing. The device is operated in the anomalous dispersion region of the waveguides and the zero dispersion of the waveguide in which conversion occurs is less than the pump wavelength so that conversion may occur for signal wavelengths above and below the zero dispersion wavelength. Conversion efficiency is in the range of 25 dB to 30 dB.

Abstract: This invention relates to a novel, all-fiber near-field scanning optical microscope (NSOM) that can have substantially improved sensitivity and signal-to-noise ratio (SNR) over the conventional NSOM design. The main advance for the all-fiber high-SNR NSOM is the use of a cleaved, flat-top fiber for collecting the light below a NSOM fiber probe with a tapered tip. The collecting fiber can be either a single-mode or a multi-mode fiber. The sample is mounted on one end of the collecting fiber, while the other end is directly coupled to a light detector. The use of fibers for both delivering and collecting light improves the sensitivity and SNR because the receiving fiber acts both as a position and angle filter, and the light is collected immediately after the sample. Moreover, for long and thin samples, the collecting fiber may be replaced by a planar waveguide structure such as a slab glass or semiconductor waveguide.

Abstract: A distributed gain medium, such as an optical fiber, is configured as a Sagnac interferometer or loop mirror, and this mirror is used as at least one of the two reflectors in the amplifier or laser. The distributed gain medium produces optical signal gain through nonlinear polarization, that may cascade through several orders. The Sagnac interferometer or loop mirror defines two optical paths that will support both common mode and difference mode optical signals. Pump fluctuations resulting from higher cascade orders are at least partially rejected through the difference mode signal path, thereby reducing the overall effect of pump fluctuation. The result is a broadband optical resonator, suitable for use at a variety of different wavelengths, including 1.3 .mu.m and 1.55 .mu.m wavelengths. Amplifiers based on this technology are "four-level," providing a pass through signal even when the pump laser is not functioning.

Abstract: The near field optical microscopy probe has a conically tapered tip formed from the inner core of a fiber optic cable. The tapered tip protrudes longitudinally from the outer cladding and has a metallized optically opaque coating over all the tip except for the light-emitting aperture at the tip apex. The optical probe is manufactured by wet chemical etching. The protruding conical tip tapers at an acute angle on the order of about 15.degree. to 60.degree., such that the tip length is on the order of a few wavelengths. By this construction, illumination traverses only a very small nonpropagating mode or evanescent mode region with resulting high optical efficiency. The probe and specimen may be supercooled, causing the metallized coating to be highly conductive and therefore optically opaque. The result is a high efficiency, high resolution probe suitable for such demanding applications as DNA sequencing.

Abstract: The near field optical microscopy probe has a conically tapered tip formed from the inner core of a fiber optic cable. The tapered tip protrudes longitudinally from the outer cladding and has a metallized optically opaque coating over all the tip except for the light-emitting aperture at the tip apex. The optical probe is manufactured by wet chemical etching. The protruding conical tip tapers at an acute angle on the order of about 15.degree. to 35.degree., such that the tip length is on the order of a few wavelengths. By this construction, illumination traverses only a very small nonpropagating mode or evanescent mode region with resulting high optical efficiency. The probe and specimen may be supercooled, causing the metallized coating to be highly conductive and therefore optically opaque. The result is a high efficiency, high resolution probe suitable for such demanding applications as DNA sequencing.

Abstract: Timing restoration for a series of input pulses is performed optically in a transmission or switching system, using a nonlinear material with negligible walk-off that also receives an essentially orthogonally polarized series of reference pulses. In the nonlinear material, the input pulses are frequency shifted by the presence of the reference pulses. For a material with negligible walk-off, the frequency shift only occurs when the pulses partially overlap, but not when the pulses are coincident. The frequency shifted output from the nonlinear material is supplied to a dispersive delay line that translates the frequency shift into a time shift, such that the input pulses are retimed by the reference pulses. If the nonlinear material has a nonlinear index of refraction n.sub.2 >0, then the dispersive delay line must have an anomalous Group Velocity Dispersion (GVD); on the other hand, if the nonlinear material has an index of refraction n.sub.2 <0, then the dispersive delay line must have a normal GVD.

Abstract: Timing restoration for a series of input pulses is performed optically in a transmission or switching system, using a nonlinear material with negligible walk-off that also receives an essentially orthogonally polarized series of reference pulses. In the nonlinear material, the input pulses are frequency shifted by the presence of the reference pulses. For a material with negligible walk-off, the frequency shift only occurs when the pulses partially overlap, but not when the pulses are coincident. The frequency shifted output from the nonlinear material is supplied to a dispersive delay line that translates the frequency shift into a time shift, such that the input pulses are retimed by the reference pulses. If the nonlinear material has a nonlinear index of refraction n.sub.2 >0, then the dispersive delay line must have an anomalous Group Velocity Dispersion (GVD); on the other hand, if the nonlinear material has an index of refraction n.sub.2 <0, then the dispersive delay line must have a normal GVD.

Abstract: It has been recognized that AlGaAs-containing planar waveguides can be advantageously used in all-optical gates for wavelengths in the range 1.2-1.7 .mu.m. In particular, such waveguides can produce in radiation pulses of center wavelength, .lambda..sub.s a phase shift of magnitude .pi. or larger while, at the same time, causing attenuation of the pulse by less than 1/e, provided hc/.lambda..sub.x <E.sub.g /2, where E.sub.g is the bandgap associated with the Al.sub.x Ga.sub.2-31 x As-contianing waveguide. In preferred embodiments .lambda..sub.s and/or x are selected such that [hc/(.lambda..sub.s -.DELTA..lambda.]<E.sub.g /2, where .DELTA..lambda. is chosen such that 99% of the pulse energy is contained in the spectral region .lambda..sub.s .+-..DELTA..lambda..

Abstract: Timing restrictions for coincidence of control and data signal pulses to a soliton-based optical logic device are significantly relaxed by predistorting a characteristic of data signal pulses input to the device. Predistortion in the form of normal dispersion is sufficient to cause each predistorted data signal pulse to change shape subsequently in the optical logic device and thereby permit effective interaction between the data signal pulses and the control pulses to achieve the desired result of the logic operation. The temporal separation between control and data signal pulses has been extended to cover a total range of up to four pulse widths without degrading the operation of the optical logic device.

Abstract: An optical logic device based on the time-shift-keying architecture is described in which digital logic functions are realized by applying appropriate signal pulses to a nonlinear shift or "chirp" element whose output is supplied to a dispersive element capable of supporting soliton propagation. In an optical fiber realization of the optical logic device, two orthogonally polarized pulses are supplied to the combination of a moderately birefringent fiber acting as the nonlinear chirp element and a polarization maintaining fiber acting as the soliton dispersive delay element having a anomolous group velocity dispersion at the signal wavelengths of interest. A nonlinear frequency shift is created in one of the pulses in the former element through cross-phase modulation and, in turn, the frequency shift is translated into a temporal shift of the affected pulse in the latter element. These devices operate at switching energies approaching 1pJ.