Ultrafast optical pulse digitization with unary spectrally encoded cross-phase modulation.

A method to digitize the intensity of ultrashort laser pulses for high-speed optical signal processing is described. This digitization was based on the spectral broadening of a weak probe (carrier) pulse by a more intense pump (signal) pulse through the nonlinear optical process of cross-phase modulation (XPM). The signal pulse intensity was varied to generate different spectral widths that can be encoded into digital form. Using a 50-ps time-divided multiplexing pulse train with a waveguide splitter, combiner, and an array of fibers with variable lengths, a unary XPM encoding approach is demonstrated. The spectral encoding scheme can be used to achieve a 5-GHz sampling rate at a 16-level accuracy.

[1]  N. Shibata,et al.  All-fibre-optic logic 'AND' gate , 1986 .

[2]  W. Tomlinson,et al.  Femtosecond white-light continuum pulses. , 1983, Optics letters.

[3]  R R Alfano,et al.  Induced spectral broadening of a weak picosecond pulse in glass produced by an intense picosecond pulse. , 1986, Optics letters.

[4]  J L Horner,et al.  Amplitude encoded phase-only filters. , 1989, Applied optics.

[5]  Michel E. Marhic,et al.  All-optical analog-to-digital and digital-to-analog conversion implemented by a nonlinear fiber interferometer , 1992 .

[6]  J P Heritage,et al.  Encoding and decoding of femtosecond pulses. , 1988, Optics letters.

[7]  Michel E. Marhic,et al.  Optical Amplification in a Nonlinear Fiber Interferometer , 1991, Optical Society of America Annual Meeting.

[8]  R. Alfano,et al.  Observation of Self-Phase Modulation and Small-Scale Filaments in Crystals and Glasses , 1970 .

[9]  J W Goodman,et al.  Optical oversampled analog-to-digital conversion. , 1992, Applied optics.

[10]  R. Alfano,et al.  High-resolution spectra of cross-phase modulation in optical fibers. , 1994, Optics Letters.

[11]  Chinlon Lin,et al.  Self-phase modulation in silica optical fibers (A) , 1978 .

[12]  Robert R. Alfano,et al.  Cross-phase Modulation and Induced-focusing of Optical Nonlinearities in Optical Fibers and Bulk Materials , 1989, Nonlinear Optical Properties of Materials.

[13]  H. Takara,et al.  Fully time-division-multiplexed 100 Gbit/s optical transmission experiment , 1993 .

[14]  J R Simpson,et al.  Cross-phase modulation in optical fibers. , 1987, Optics letters.

[15]  M. Saruwatari,et al.  Ultrafast polarisation-independent optical demultiplexer using optical carrier frequency shift through crossphase modulation , 1992 .

[16]  Y. Shen,et al.  Spectral broadening of ultrashort pulses in a nonlinear medium. , 1984, Optics letters.

[17]  R. Alfano,et al.  Single-pulse degenerate-cross-phase modulation in a single-mode optical fiber. , 1995, Optics letters.

[18]  J G Fujimoto,et al.  Ultrafast switching with a single-fiber interferometer. , 1989, Optics letters.

[19]  Michel E. Marhic,et al.  All-optical logic gates based on cross-phase modulation in a nonlinear fiber interferometer , 1991, Nonlinear Guided-Wave Phenomena.