Abstract: Methods and apparatuses are provided for determining characteristics of an input optical signal in an optical network. An optical signal monitoring apparatus estimates a minimum time interval between transitions in the input signal, determines a clock signal based on the estimated minimum time interval, and performs a time domain measurement on the input signal based on the determined clock signal. The optical signal monitoring apparatus samples the input signal based on the determined clock signal and determines the characteristics of the input signal.

Abstract: Methods and apparatuses consistent with the present invention recover a clock signal from a variable bit rate data signal by estimating, in the time domain, the bit rate of the data signal, and based on the estimated variable bit rate, determining a center frequency of a narrow-band filter for extracting the clock signal from the data signal. A clock recovery circuit consistent with the present invention extracts a clock signal from a variable bit rate data signal by estimating a minimum time interval between transitions in the data signal, generating a plurality of pulses that correspond respectively to transitions in the data signal, adjusting the duration of each of the pulses based on the estimated minimum time interval and inputting into a narrow-band filter the adjusted pulses, determining a center frequency of the narrow-band filter based on the estimated minimum time interval, and extracting in the narrow-band filter the clock signal from the adjusted pulses.

Abstract: A Josephson junction (100) is employed as a very-high-speed frequency demodulator for detecting a frequency-shift-keyed (FSK) modulated signal (201) in a microwave or lightwave communication system. The voltage induced across the junction in response to an incident FSK modulated radiation signal follows the frequency variations in the incident wave thereby directly demodulating the information signal from its carrier. In the disclosed embodiment an FSK modulated optical signal is mixed with a local oscillator (303) signal, which is then incident on a photodetector (305). The resultant microwave-frequency signal is then applied over a two-wire transmission line (308) to the Josephson junction (307) for direct demodulation.

Abstract: An improved molded optical fiber connector is achieved using an insert (111) disposed about the optical fiber. During molding, filler material (112) pushes the insert along the optical fiber (106) until it abuts a mold surface (110) comprising a portion of the connector mating end. This sliding action reduces any bends in the fiber and controls the position and angle of the fiber relative to the mating end. Use of the insert is suitable for the molding of low-loss monomode or multimode optical fiber connectors.