Abstract: A polarization modulation device for wideband laser comprises a first polarization maintaining optical fiber, a second polarization maintaining optical fiber, and a non-polarization maintaining optical fiber. The non-polarization maintaining optical fiber includes a first polarization controller coupled with the first polarization maintaining optical fiber, and a second polarization controller coupled with the second polarization maintaining optical fiber.

Abstract: Provided are optical switches applicable to various safety apparatuses which can control an operation of a circuit by detecting a switching signal such as pathogens and toxic substances, and safety apparatuses using the optical switches. The optical switch comprises an optical irradiation unit to irradiate light; an optical interference unit which can interact with a switching signal, interferes with light irradiated from the optical irradiation unit and radiates it as interference light, and can vary the wavelength of the interference light after interaction with the switching signal; and a switching unit which is provided in the path of the interference light, detects a wavelength change of the interference light, and conducts one of activating and deactivating a circuit. The safety appatatus comprises the optical switch and a hazard evasive apparatus activating unit which activates a hazard evasive apparatus using the optical switch.

Abstract: A transmitting device generates a modulation signal depending on data to be transmitted. The transmitting device includes a transmission frequency generation device that is controlled depending on the signal in order to produce a transmission frequency corresponding to the modulation signal. A calibration device is provided for automatically calibrating the amplitude of the modulation signal during the operation of the transmitting device. This eliminates time-consuming and therefore costly adjustment steps during the production of the transmitting device.

Abstract: The digital phase detector detects a phase shift between a comparison clock pulse signal (VT) and a reference clock pulse signal (RT). It includes logic gates (STO,STA) for generating start and stop pulses from respective successive pulses of the comparison and reference clock pulse signals (RT,VT). A counter (ZG,Z) counts the pulses of a counter clock pulse signal (ZT) of a higher frequency in a time window between the start signal and the subsequent stop signal. The counter value of the counter is a measure of the phase shift between the comparison and reference clock pulse signals (VT,RT). Quantization errors in the phase shift signal are considerably reduced by providing a logical gate (VZ) for determining the sign of the phase shift and a device (.mu.P) for adding a constant, advantageously 0.5, to the counter value.