Lucent Technologies Inc.

Jeffrey Matthew Roth

Chunhui Xu

Wayne Harvey Knox

Daniel Charles Kilper

Hernando Garcia

A photomultiplier module (PMT), preferably a PMT with a gallium arsenide (GaAs) photocathode, is used as a N-photon detector (N is an integer &#x2267;2). The PMT detects the N-photon absorption rate of an optical signal having a wavelength range extending from 1.0 &#x3bc;m to an upper wavelength region that increases as the number of photons simultaneously absorbed by the PMT increases beyond two. The N-photon absorption rate is used by a signal compensation apparatus to reduce impairments which affect the rate, such as group velocity dispersion and/or polarization mode dispersion, in a received optical pulse communication signal. The N-photon absorption rate can also be used to determine the optical signal-to-noise ratio of a received optical pulse communication signal, and/or to synchronize a second optical pulse signal with the first optical signal.

Dynamic measurement of and compensation for impairments to optical data communication pulses

Apparatus and method is described for using a silicon photon-counting avalanche photodiode (APD) to detect at least two-photon absorption (TPA) of an optical signal, the optical signal having a wavelength range extending from 1.2 &#x3bc;m to an upper wavelength region that increases as the number of photons simultaneously absorbed by the APD increases beyond two. In one embodiment, the TPA count is used by a signal compensation apparatus to reduce dispersion of a received optical pulse communication signal subjected to group velocity dispersion, polarization mode dispersion, or other signal impairment phenomena which effect the TPA count. Another embodiment, the TPA count is used to determine the optical signal-to-noise ratio of a received optical pulse communication signal. Another embodiment uses the TPA count to determine the autocorrelation between a first and second optical pulse signals as a function of the relative delay between the first and second optical pulse signals. Another embodiment uses the TPA count to achieve synchronization of a second optical pulse signal to a first optical pulse signal.

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Lexington, MA, United States of America

Jeffrey Matthew Roth