Abstract: Power scaling by multiplexing multiple fiber gain sources with different wavelengths, pulsing or polarization modes of operation is achieved through multiplex combining of the multiple fiber gain sources to provide high power outputs, such as ranging from tens of watts to hundreds of watts, provided on a single mode or multimode fiber.

Abstract: In accordance with the present invention, optical channels to be demultiplexed are supplied to first and second optical fibers via an optical splitter. Low loss interference filters, for example, coupled to the first and second optical fibers, select respective groups of channels. Each group of channels is next demultiplexed with sub-demultiplexers into individual channels, each of which is then sensed with a corresponding photodetector. Although the optical splitter introduces an optical power loss at the input to the demultiplexer, the interference filters and sub-demultiplexers create little additional loss. As a result, the total power loss associated with the present invention is significantly less than that obtained with a conventional n channel demultiplexer based on a 1×n splitter. Accordingly, large numbers of channels, e.g., in excess of forty can be readily demultiplexed and detected.

Abstract: In accordance with the present invention, optical channels to be demultiplexed are supplied to first and second fibers via an optical splitter. Low loss interference filters, for example, coupled to the first and second optical fibers, select respective groups of channels. Each group of channels is next demultiplexed with sub-demultiplexers into individual channels, each of which is then sensed with a corresponding photodetector. Although the optical splitter introduces an optical power loss at the input to the demutiplexer, the interference filters and sub-demultiplexer create little additional loss. As a result, the total power loss associated with the present invention is significantly less than that obtained with a conventional n channel demultiplexer based on a 1×n splitter. Accordingly, large numbers of channels, e. g., in excess of forty can be readily demultiplexed and detected.

Abstract: Power scaling by multiplexing multiple fiber gain sources with different wavelengths, pulsing or polarization modes of operation is achieved through multiplex combining of the multiple fiber gain sources to provide high power outputs, such as ranging from tens of watts to hundreds of watts, provided on a single mode or multimode fiber.

Abstract: Power scaling by multiplexing multiple fiber gain sources with different wavelengths, pulsing or polarization modes of operation is achieved through multiplex combining of the multiple fiber gain sources to provide high power outputs, such as ranging from tens of watts to hundreds of watts, provided on a single mode or multimode fiber.

Abstract: An optical fiber used as the active amplifying medium in a fiber laser is arranged to have a high insertion loss at an undesired frequency, while retaining a low insertion loss at a desired lasing frequency. In one embodiment, loss at a Raman-shifted frequency is introduced by using an optical fiber which has multiple claddings with an index profile that includes an elevated index region located away from the core, but within the evanescent coupling region of the core. A distributed loss, which can be enhanced by bending, is produced at the Raman frequency which effectively raises the threshold at which Raman scattering occurs in the fiber and therefore results in a frequency-selective fiber. In another embodiment, an absorbing layer is placed around the core region. The absorbing layer is chosen to have a sharp absorption edge so that it absorbs highly at the Raman-shifted wavelength, but minimally at the desired lasing wavelength.

Abstract: An optical fiber used as the active amplifying medium in a fiber laser is arranged to have a high insertion loss at an undesired frequency, while retaining a low insertion loss at a desired lasing frequency. In one embodiment, loss at a Raman-shifted frequency is introduced by using an optical fiber which has multiple claddings with an index profile that includes an elevated index region located away from the core, but within the evanescent coupling region of the core. A distributed loss, which can be enhanced by bending, is produced at the Raman frequency which effectively raises the threshold at which Raman scattering occurs in the fiber and therefore results in a frequency-selective fiber. In another embodiment, an absorbing layer is placed around the core region. The absorbing layer is chosen to have a sharp absorption edge so that it absorbs highly at the Raman-shifted wavelength, but minimally at the desired lasing wavelength.

Abstract: In accordance with the present invention, an in-line fiber Bragg grating is coupled to the output of a directly modulated DFB laser. The grating preferably rejects chirp induced frequencies of light emitted by the DFB laser. Accordingly, light transmitted through the grating is spectrally narrowed and has a higher extinction ratio, thereby decreasing bit error rate probabilities.

Abstract: A waveguide coupler comprises at least a first waveguide coupled at a coupling region to a second waveguide such that at least a part of radiation propagating along the first waveguide is coupled into the second waveguide. The second waveguide comprises a diffraction grating disposed at the coupling region to inhibit coupling of radiation from the first waveguide into the second waveguide at wavelengths characteristic of the diffraction grating.

Abstract: A fiber laser uses a chirped Bragg grating as the output coupler and the grating is oriented so that the grating period increases in the direction towards the end of the cavity--the "red" end of the grating is at the output coupling end of the cavity. This grating orientation unexpectedly produces a relatively large reduction in the noise generated by the fiber laser. In one embodiment, the chirped Bragg grating is produced by transversely doping spaced-apart portions of the longitudinal fiber core with elements that modify the refractive index of the core. The "chirp" in the grating period is produced by modifying the period of the transversely doped fiber core portions during manufacture of the grating. In another embodiment, a partially reflective chirped fiber grating is used at the input side of the laser as well as at the output side.

Abstract: An optical fiber used as the active amplifying medium in a fiber laser is arranged to have a high insertion loss at an undesired frequency, while retaining a low insertion loss at a desired lasing frequency. In one embodiment, loss at a Raman-shifted frequency is introduced by using an optical fiber which has multiple claddings with an index profile that includes an elevated index region located away from the core, but within the evanescent coupling region of the core. A distributed loss, which can be enhanced by bending, is produced at the Raman frequency which effectively raises the threshold at which Raman scattering occurs in the fiber and therefore results in a frequency-selective fiber. In another embodiment, an absorbing layer is placed around the core region. The absorbing layer is chosen to have a sharp absorption edge so that it absorbs highly at the Raman-shifted wavelength, but minimally at the desired lasing wavelength.

Abstract: An optical fibre distributed feedback laser comprises an amplifying optical fibre (50) operable to provide optical gain at a lasing wavelength, in which a diffraction grating (30) is disposed on at least a portion of the amplifying optical fibre to provide distributed optical feedback for sustaining lasing action at the lasing wavelength.