Abstract: The object of the invention is to offer a light source device for frequency division multiplexed optical communications having a compact size and reduced cost. Light source units 100-300 output light having optical frequencies which oscillate at mutually different modulation frequencies centered about mutually different optical frequencies. Optical splitters 1-3 split the output light from each light source unit into two parts. An optical multiplexer-splitter 4 multiplexes and splits the output light from the optical splitters. The Fabry-Perot etalon resonator 5 transmits each component of the output light from the optical multiplexer-splitter 4 at a specific transmission rate corresponding to each optical frequency. A light receiving element 6 converts the output light from the Fabry-Perot etalon resonator 5 into an electrical signal, and a light receiving element 7 converts the output light from the optical multiplexer-splitter 4 into an electrical signal.

Abstract: A generator of energy-depleted radiation and various methods and applications using the energy-depleted radiation. Various embodiments are disclosed of the energy-depleted radiation generator and an energy-restored radiation generator, which permits detection of wave properties of the radiation without regard to the depletion of its energy. The energy-depleted radiation generator functions in one embodiment by selective transmission of destructively interfering radiation. Other embodiments use two-beam coupling or directional coupling to achieve energy depletion. Restoring energy to an energy-depleted radiation beam is accomplished by transferring energy to it from a reference beam, in a beam-to-beam transfer or in an optical amplifier. The invention has important applications in fields such as communications, specimen analysis, photorefractive recording, holography, and other fields in which the reduction of energy content in the associated radiation is advantageous.

Abstract: In a fiber-optic communications system, a shut-down apparatus in the event of a fiber-optic cable disruption includes a first optical fiber cable for propagating signals in a first direction and having a plurality of adjacent amplifiers disposed along the first cable. A second optical fiber cable for propagating signals in a second direction, opposite the first direction, includes a plurality of adjacent amplifiers disposed along the second cable. Each of the amplifiers in the second optical fiber cable are interconnected to one of the amplifiers of the first optical fiber cable to form a plurality of amplifier pairs. Circuitry is provided for terminating operation or reducing the output power level of an amplifier within the first or second optical fiber cables in the event of a cable disruption between adjacent amplifier pairs, such that an amplifier within an amplifier pair adjacent to the cable disruption terminates generation or reduces its power level to a safe level at its output.