Abstract: A variable pulse width optical pulse generation system includes a first and a second optical interferometric modulator. A first drive signal applied to the first modulator modulates an input optical signal, so as to provide a first modulated optical signal. A second drive signal applied to the second modulator modulates the first modulated optical signal, producing output optical pulses. One or both of the drive signals may be formed by superposing a plurality of waveforms having different frequencies, for example a base frequency and its odd harmonics. By adjusting the relative amplitudes of the drive signals, or the relative amplitudes of the component waveforms forming the drive signals, the pulse width and the extinction ratio of the output pulses can be varied so as to achieve an optimal value.

Abstract: A system for generating variable pulse width optical pulses includes an optical modulator, and means for generating an electrical modulation signal. The optical modulator includes an optical input for receiving an input optical signal, a modulation input for receiving the electrical modulation signal that modulates the input optical signal, and an optical output for providing output optical pulses resulting from the modulation of the input optical signal. The electrical modulation signal is formed by combining a base waveform with one or more odd harmonics of the base waveform. The pulse widths of the output optical pulses can be precisely controlled, by adjusting the relative amplitudes and phases of each of the constituent waveforms that form the modulation signal. The system can be used as part of a variable transmission window OTDM demultiplexer.

Abstract: An apparatus and method for cleaving optical waveguides to precise differential length are described. A first end of a waveguide is coupled to an input port of a reflectometer. A reference mirror is then positioned in a path of radiation propagating through the second end of the waveguide. A waveguide cutting tool is then positioned proximate to the waveguide and at a distance relative to a reference mirror. A first reflectometry measurement is performed on the waveguide to a second end of the waveguide. A second reflectometry measurement is performed on the waveguide to the reference mirror. The waveguide is then positioned relative to the reference mirror and waveguide cutting tool so that the first reflectometery measurement is a measurement increment apart from the second reflectometry measurement. The waveguide is then cut with the cutting tool positioned at the distance relative to the reference mirror.

Abstract: An apparatus and method for demultiplexing a time and polarization multiplexed signal are described. The multiplexed signal is a combination of component signals, each of which is characterized by a polarization. The demultiplexer of the system includes an input interface over which the signal is received. A polarization demultiplexer receives the multiplexed signal and polarization demultiplexes the signal. Next, a time-demultiplexing stage time-demultiplexes the polarization-demultiplexed signal to recover the original component signals. A clock recovery circuit recovers the clock from the polarization-demultiplexed signal before time demultiplexing.

Abstract: A phase-modulated fiber optic communication link (9) with carrier signal filtering is disclosed. The phase-modulated fiber optic communication link (9) includes a laser (11) that produces a optical carrier signal that is conveyed by an optical fiber (13) to a phase modulator (15). A modulated RF signal phase modulates the optical carrier signal and produces a phase-modulated signal comprising a carrier component (27), an upper sideband (29), and a lower sideband (31). The upper and lower sidebands are out of phase by 180 degrees. The phase-modulated signal is conveyed by an optical fiber to a delay line filter (21). In one embodiment of the invention, the delay line filter (21) attenuates the power of the optical carrier signal and passes the sidebands substantially unattenuated. One of the sidebands is phase shifted by 180 degrees by the delay line filter. The output of the delay line filter is applied to a photodiode detector (23), which recovers the RF modulated signal.

Abstract: A method and apparatus for improving the signal-to-noise ratio (SNR) and dynamic range of an optical fiber system. An optical fiber system (10) includes a laser(12) that produces a coherent light signal conveyed over an optical fiber (14) to a Mach-Zehnder modulator (16). An input signal modulates the coherent light, producing modulated side bands, which together with the carrier comprise a modulated light signal. The modulated light signal is filtered using an integrated optical filter (24) that substantially attenuates the carrier frequency, while passing light at the frequency of the modulated side bands. A detector (28) demodulates the filtered light with a substantially greater SNR than would otherwise have been possible. In one preferred form of the invention, the integrated optical filter comprises an imbalanced interferometer (40), and in another embodiment, tile interferometer produces imperfect nulls aligned with the carrier frequency.