We review our recent work on the generation of time- and
wavelength-interleaved laser pulses and their applications in
optical signal processing. Using phase and amplitude modulation on four continuous-wave lasers at ~1550 nm followed
by chirp compensation, we have generated < 6 ps pulses switched sequentially among 4 center wavelengths with a
repetition rate of 80 GHz. The pulses are nearly transform limited with a time-bandwidth product ~ 0.464. We applied
time- and wavelength-interleaved pulses for new applications in nonlinear processing of communication signals. Fourwavelength
DPSK multicasting with simultaneous NRZ-to-RZ pulse format conversion has been achieved with fourwave
mixing. In addition, using optical parametric amplification with the interleaved pulses, we have demonstrated
reconfigurable 40 Gb/s OTDM demultiplexing, as well as amplitude noise reduction in DPSK wavelength multicast.
We report some of our recent results on all-optical wavelength conversion including result on broadband orthogonal pumped four-wave-mixing in semiconductor optical amplifiers and dual-wavelength injection-locking of a Fabry- Perot laser diode. The high speed performance of wavelength conversion buy dual-wavelength injection locking of a Fabry- Perot laser was investigated experimentally and we present for the first time results on wavelength conversion at 10Gbit/s using dual wavelength injection-locking of a Fabry- Perot laser diode. The experimental results for all-optical wavelength conversion using broadband orthogonal pumping in a fiber ring containing a semiconductor optical amplifier is described. We also describe the latest result on a 40Gbit/s polarization independent all-optical wavelength converter based on polarization diversity and four-wave-mixing in a single semiconductor optical amplifier.
In white light interferometry, the measurement resolution is limited relatively by the coherence length of the light source, usually in tens of fringes. By the use of two wavelength combination and multi-wavelength combination source approaches, the equivalent coherence length can be decreased to a few fringe level and nearly one fringe level respectively. By employing a discrete fringe pattern transform technique, the equivalent coherence length can be further reduced to a sub-fringe level, representing a high potential in high precision white light interferometric measurement.
Interdiffusion and reaction at the interface between an YBaCuO film and a Si substrate degrade the superconductivity of the film. Using a buffer layer, the film-substrate interaction can be reduced. Thus, a superconducting thin film is formed on a silicon substrate. A new method of patterning superconducting thin films based on the Si-YBaCuO intermixing has been developed. On a silicon substrate, a thin layer of noble metal was first evaporated and patterned using photolithography. An YBaCuO film was then deposited by e-beam evaporation and annealed in a rapid thermal processing system. After a high temperature annealing, the patterned feature became superconducting separated by Si-YBaCuO intermixed areas. Superconducting micron-sized the structures with Tc of 73 K have been demonstrated. This patterning technique may be useful for making high-Tc superconducting interconnects and devices on a Si wafer.