Femtosecond Optical Pulse Generation Using Laser Diodes

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The purpose of our study is to develop a highly-nonlinear device responding to femtosecond optical pulses and to find a method for optical pulse monocyclization to break through the present shortest pulse. Results of our study are summarized as follows.1. From the femtosecond optical pulse nonlinear propagation experimetnt in germanium oxide or erbium : germanium oxide doped silica fibers, we first evaluated their nonlinear refractive indices and response times. The nonlinear refractive indices are several times larger than that of a silica fiber and the response times are in a range of a few femtoseconds.2. We built up a highly sensitive femtosecond time-division interferometer using a heterodyne detection technique. With this interferometer, we evaluated the nonlinear refractive index in a highly lead oxide doped silica fiber to be about ten times larger than that of a silica fiber.3. Numerical calculation of femtosecond optical pulse nonlinear propagation in an organic crystal-cored … More fiber whose response time is 30 fs was performed. From this calculation, it was found that the influence of the delayd response on pulse compression can be compensated for by the third-order phase adjustment.4. Using a time-division interferometer, we first measured two (parallel and perpendicular) components of nonlinear-refractive-index change in carbon disulfide with high accuracy. We decomposed each component into three contributions based on decay time constants.5. An approach for generation of an ultrabroad-band optical pulse (550 THz width) is proposed, which is based on mutual induced phase modulation of three synchronized femtosecond pulses in a short fiber. These pulses having equidistant carrier frequencies and constant carrier-phase differences are obtained from the fundamental, the second-harmonic and the second-harmonic-pulse pumped parametric waves. Computer analysis shows that chirp of the composite wave at the fiber output can be compensated for by a spatial phase modulator and a 1.76-cycle pulse is generated. Less