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Infrared spectroscopy using semiconductor lasers is a promising technique for trace gas detection. It allows a continuous and real time monitoring of several species, with a high sensitivity and a good selectivity. Among all the possible methods two are pa ...
An experimental method is presented for characterization of the combined intensity and frequency modulation produced when the injection current of a laser diode is modulated. The reported technique is based on the analysis of the harmonic signals produced ...
An all-fiber phase-modulated master oscillator power amplifier for free-space coherent communication is presented. A distributed-feedback fiber laser at 1.06 μm is used as master oscillator. A novel phase modulator based on a ZnO-coated single-mode fiber m ...
We present femtosecond gain measurements in microcavity-embedded quantum wells. When the excitonic transition is saturated by an intense pump field, the spectrum measured with a weak probe pulse is strongly modulated by pump-probe wave mixing processes. A ...
We propose the use of spectral phase conjugation to compensate for dispersion of all orders, self-phase modulation, and self-steepening of an optical pulse in a fiber. Although this method cannot compensate for loss and intrapulse Raman scattering, it is s ...
For a general class of constant-energy trellis-coded modulation schemes with 2ν states, necessary and sufficient conditions to guarantee that a maximum-likelihood sequence estimator can decode each symbol with a fixed delay of ν symbols are deri ...
Pulse amplitude modulation scheme with the same spectral efficiency as QAM, that is twice the spectral efficiency of conventional PAM schemes, comprising the steps of: (1) forming a train of pulses q(t -kT/2) = p(t - k T/2)cos2 pi fo(t- k T/2), wherein p(t ...
A theoretical model of wavelength modulation spectroscopy that uses a laser diode on a Lorentzian absorption line is presented. This theory describes the general case of a current-modulated semiconductor laser for which a combined intensity and frequency m ...
We report on the application of double-clad doped fiber amplifiers for coherent space communication systems using a master oscillator power amplifier (MOPA) design at 1.06 μm. The master oscillator is either a single-frequency Nd:YAG solid-state laser or a ...
For a general class of constant-energy trellis-coded modulation schemes with 2 ? states, necessary and sufficient conditions to guarantee that a maximum-likelihood sequence estimator can decode each symbol with a fixed delay of ? symbols are derived. Addit ...
