Abstract: An optical amplifier is used as a frequency-selective high-gain element in a subcarrier-multiplexed fiber optic transmission system. A high-speed diode laser optical transmitter is modulated by a plurality of independent information channels that are carried on separate, appropriately spaced carrier frequencies. An optical receiver, coupled to the transmitter by way of an optical fiber, includes a narrow-bandpass semiconductor laser optical amplifier having a gain bandwidth smaller than wavelength distances between adjacent ones of the carrier frequencies, a photodetector coupled to the output of the amplifier, and polarization controlling means coupled to the fiber in front of the optical amplifier for maximizing gain in the optical amplifier.

Abstract: A tunable optical amplifier is used as a wavelength-selective high-gain element in a subcarrier-multiplexed fiber optic transmission system for providing a direct optical domain-to-baseband conversion of a selected optical channel. A high-speed diode laser optical transmitter is modulated by a plurality of independent information channels that are carried on separate, appropriately spaced carrier frequencies. An optical receiver, coupled to the transmitter by way of an optical fiber, includes a tunable narrow-bandpass semiconductor laser optical amplifier having a gain bandwidth smaller than wavelength distances between adjacent ones of the carrier frequencies, a photodetector coupled to the output of the amplifier, and polarization controlling means coupled to the fiber in front of the optical amplifier for maximizing gain in the optical amplifier.

Abstract: Electrical signals with frequencies ranging from several tens of megahertz to hundreds of gigahertz are generated by detecting the optical output from a novel double-external-cavity diode laser system. The system provides a convenient means of measuring the frequency response of high speed photodetectors, and it can also be used for the optical generation and transmission of microwave or millimeter wave carriers in applications such as phased array radars.

Abstract: A monolithic external-coupled-diode laser structure uses high reflectivity facet coatings to reduce the operating current and to improve suppression of unwanted longitudinal modes.

Abstract: A monolithic external-coupled-diode laser structure uses high reflectivity facet coatings to reduce the operating current and to improve suppression of unwanted longitudinal modes.

Abstract: A dichroic beamsplitter includes two glass prisms, each having an isosceles right triangular cross section, with a multilayer dielectric coating sandwiched therebetween. Each layer of the coating is tuned for quarter-wave operation with 45.degree. incidence of light at 0.83 .mu.m. The coating comprises 53 layers of three different materials arranged in a specific order. The materials have refractive indexes of 1.45, 1.625, and 2.25 and can be, for example, silicon dioxide, aluminum oxide, and titanium oxide. An optical fiber transmission system includes an optical fiber and a beamsplitter at opposite ends thereof. One of the beamsplitters is oriented with respect to the fiber at 43.degree. incidence and has a high nonpolarizing reflectance at a wavelength .lambda..sub.2 and a low loss transmission at a wavelength .lambda..sub.1. The other beamsplitter is oriented with respect to the fiber at a 47.degree. incidence and has a high nonpolarizing reflectance at the wavelength .lambda..sub.