David O. Caplan

Characterization of dynamic optical nonlinearities by continuous time-resolved Z-scan

Dynamic optical nonlinearities are investigated with a dual-beam (pulsed-pump, cw probe) Z-scan technique. Monitoring of probe transmission after strong pump excitation permits determination of time-varying parameters such as nonlinear refraction n(I, t) and absorption alpha(I, t). Continuous time resolution provides an efficient means of measuring and distinguishing fast and slow nonlinear mechanisms such as electronic, free-carrier, and thermal effects observed in semiconductors. We demonstrate this technique in CdTe and measure bound-electronic refraction; two-photon absorption; free-carrier refraction, absorption, and diffusion; thermal refraction and temperature changes; and related time constants.

High-Sensitivity Demodulation of Multiple-Data-Rate WDM-DPSK Signals using a Single Interferometer

We demonstrate simultaneous reception of multiple-rate wavelength-division-multiplexed optical- DPSK signals using a single interferometer. The demodulation approach provides rate-flexibility and scalability, enabling penalty-free performance and compliance with existing channel-rate and channel-spacing standards.

Optical phase conjugation with gain in a bulk semiconductor

We experimentally demonstrate a method of high-speed optical amplification using degenerate four-wave mixing in a bulk semiconductor CdTe. In our experiment, both transmitted probe and phase-conjugate beams are amplified in accordance with theory. We propose that this approach, which performs optical splitting with gain, can be used with multiple input signals, leading to potential applications including image amplification, information distribution, and optical computing.