Mid-infrared nonlinear optical response of Si-Ge waveguides with ultra-short optical pulses

Optical parametric generation of nearly transform-limited mid-infrared pulses in dispersion-engineered nonlinear waveguides.

Optical parametric generation in dispersion-engineered waveguides fabricated by proton exchange in periodically poled lithium niobate is numerically investigated as a means for producing widely tunable mid-infrared ultrashort pulses starting from low energy pump pulses at a 1.55 microm wavelength and with 100 fs duration, which are typical parameters of amplified Er-fiber oscillators. Numerical...

Generation of Ultra-short Optical Pulses Using Nonlinear Dynamics

Quadrature squeezing with ultrashort pulses in nonlinear-optical waveguides.

Using ultrashort laser pulses, we have observed quadrature squeezing and parametric gain in quasi-phase-matched KTiOPO(4) waveguides. Using a local oscillator pulse that is 2.5 times shorter than the squeezed pulse, we observed noise reduction of 12 +/- 1% below the shot-noise level. Parametric amplification and deamplification of a coherent seed pulse have also been observed, with no indicatio...

Quantum coherent saturable absorption for mid-infrared ultra-short pulses.

We theoretically show that quantum coherent saturable absorption can be used to obtain ultra-short pulses from mid-infrared quantum cascade lasers (QCLs). In this proposal, quantum cascade structures are processed as two electrically isolated sections. The two sections will be biased with two different voltages so that one of the sections produces gain as is done in typical QCLs, while the othe...

Nonlinear optical response of Ge nanocrystals in silica matrix with excitation of femtosecond pulses

We report an investigation of third-order optical nonlinearities in Ge nanocrystals (∼ 6 nm radius) embedded in silica matrix using the Z-scan and pump-probe techniques with femtosecond laser pulses at 780-nm wavelength. The nanocrystallite Ge samples were prepared using magnetron co-sputtering and post-thermal annealing at 800 ◦C. The nonlinear absorption coefficient and refractive index of th...