Abstract: A digital modulator provides high speed modulation of a semiconductor diode laser or light emitting diode. The circuit is compatible with standard TTL and ECL integrated logic circuits and operates with a positive ground for convenient heat sinking.

Abstract: A solid state circuit, which serves as a twin simplex/half-duplex converter, includes a triple input NAND gate. The output of the NAND gate is connected directly to the outgoing simplex conductor. Signals on the incoming simplex conductor are applied to the three inputs of the NAND gate through separate signal paths which introduce different delays. One signal path introduces an intermediate delay before applying the incoming signal to the NAND gate in an inverted form. The half-duplex line is connected to this signal path. While incoming signals are applied to all three inputs to the NAND gate as well as to the half-duplex line, a lack of coincidence at the inputs prevents any incoming signal from passing through the converter to the outgoing simplex line.

Abstract: A light switch for controlling the transmission of optical energy through optical fibers includes a hollow, light-transmitting tube extending transversely across the end of at least one light transmitting fiber. The tube contains one or more masses of light diverting material in a matrix of light-transparent fluid. The masses of light diverting material may be reflective, refractive or absorbent. Means are provided for varying the pressure along the tube to shift the masses relative to the light transmitting fiber so as to divert or pass the light to receiving fibers.

Abstract: A PIN photodiode structure uses direct side entry into the I region, thus permitting the use of thicker P and N regions with a comparatively thin I region without sacrificing speed and results in more constant spatial distribution upon carrier generation and longer wave length devices with conventional speeds or smaller devices at faster speeds, and may be integrated on the same chip with associated circuits.