Abstract: An optical transmission system utilizing a nonlinear fiber demultiplexer. A time division multiplexed optical signal is transmitted via a first optical signal path. An optical pump pulse is transmitted via a second optical signal path. The optical pump pulses are synchronized to correspond to the pulses in the multiplexed optical signal for which extraction is desired. The first and second optical signal paths are coupled such that the portions of the multiplexed signals which are synchronized with the optical pump pulses are amplified through Raman gain. The resulting signal is detected and passed through a threshold detector which filters out pulses below an intensity threshold. The desired demultiplexed signal, which was amplified by the pump pulses, passes through the optical threshold detector as an electronic pulse.

Abstract: A self-tuning optical waveguide filter for attenuating a lower power light signal at .lambda..sub.1 more than a higher power signal at .lambda..sub.2 comprises a length of single core waveguide and a light injector for applying .lambda..sub.1, .lambda..sub.2 into the waveguide in two propagating modes subject to mode beating. The mode beating produces high intensity regions of .lambda..sub.1 physically displaced from high intensity regions of .lambda..sub.2. A portion of the waveguide is doped with a saturable absorber for disproportionately attenuating wavelengths at lower power levels. Advantageously the waveguide is a single-core fiber having its central core doped with rare-earth saturable absorber. In a preferred embodiment, the fiber is dimensioned to propagate .lambda..sub.1, .lambda..sub.2 in the LP.sub.01 and LP.sub.02 modes, and the saturable absorber is Erbium.

Abstract: A method for launching a high-power signal into anomalous-dispersion fiber without suffering excess spectral broadening and waveform distortion. A high-power signal is launched as very short optical solitons, typically with a pulse width of approximately 1 to 10 ps. The pulse width of the solitons will broaden adiabatically (or nearly adiabatically) as they propagate down the anomalous-dispersion fiber as the average power of the soliton decreases. At the same time, the optical spectrum will narrow. After some distance of travel, when the width of the pulses have broadened to a suitable duration and the average power has decreased to a point where penalties from nonlinearities are insignificant, the pulses enter a significantly linear propagation regime with first order dispersion near zero. A dispersion-shifted fiber may be used or any additional dispersion can be compensated at the receiver. Consequently, no further significant broadening of the spectrum occurs when the signal is received at the receiver.

Abstract: A tunable radiation source employing the stimulated Raman-scattering process is disclosed. The source generates several orders of Stokes radiation in an optical-fiber oscillator cavity, which Stokes radiation may be independently tuned by incorporating separate tuning elements for the several Stokes orders. Several different arrangements of fiber and tuning elements are disclosed.

Abstract: There is disclosed a time-dispersion tuned Raman oscillator which makes use of the frequency-dependent transit time of Stokes radiation through a long optical fiber. Time-dispersion tuning is effected by synchronizing Stokes radiation of the desired frequency with a pump pulse. This synchronization may be accomplished either by adjusting the delay of the feedback pulse relative to a pump pulse or by adjusting the repetition rate of the pulsed pump laser.