Robert B. Lee

Wavelength conversion for WDM communication systems using four-wave mixing in semiconductor optical amplifiers

Four-wave mixing (FWM) in semiconductor optical amplifiers is an attractive mechanism for wavelength conversion in wavelength-division multiplexed (WDM) systems since it provides modulation format and bit rate transparency over wide tuning ranges. A series of systems experiments evaluating several aspects of the performance of these devices at bit rates of 2.5 and 10 Gb/s are presented. Included are single-channel conversion over 18 nm of shift at 10 Gb/s, multichannel conversion, and cascaded conversions. In addition time resolved spectral analysis of wavelength conversion is presented.

Wavelength conversion up to 18 nm at 10 Gb/s by four-wave mixing in a semiconductor optical amplifier

We characterize the conversion bandwidth of a four-wave mixing semiconductor optical amplifier wavelength converter. Conversion of 10-Gb/s signals with bit-error-rate (BER) performance of <10/sup -9/ is demonstrated for wavelength down-shifts of up to 18 nm and upshifts of up to 10 nm.

Synthesis of luminescent silicon clusters by spark ablation

The synthesis of luminescent nanometer-scale Si clusters by spark ablation from a crystalline Si substrate is described. The cluster source, described in the text, generates clusters in a flowing Ar stream at atmospheric pressure. Electron microscopy reveals that the clusters have diameters in the 2-4 nm size range. The luminescence spectra of the clusters, similar to that of porous Si, are presented.

Cascaded wavelength conversion by four-wave mixing in a strained semiconductor optical amplifier at 10 Gb/s

We demonstrate for the first time cascaded wavelength conversion by four-wave mixing in a semiconductor optical amplifier. Bit-error-rate performance of <10/sup -9/ at 10 Gb/s is achieved for two conversions of up to 9 nm down and up in wavelength. For two wavelength conversions of 5 nm down and up, a power penalty of 1.3 dB is measured. A system of two wavelength converters spanning 40 km of single-mode fiber is also demonstrated.

High performance planar lightwave circuit triplexer with passive optical assembly

High performance, compact planar lightwave circuit based triplexers have been built and tested. The triplexers utilize lasers, photodiodes and filters that have been adapted to enable passive optical assembly of the triplexer.

Direct determination of the ambipolar diffusion length in strained InxGa1−xAs/InP quantum wells by cathodoluminescence

The ambipolar diffusion length is measured in strained InxGa1−xAs/InP quantum wells for several mole fractions in the interval 0.3<x<0.8 by cathodoluminescence. The ambipolar diffusion length is found to have a significantly higher value in the lower indium mole fraction samples corresponding to tensile-strained wells. This longer diffusion length for the tensile samples is consistent with results of carrier lifetime experiments by M. C. Wang, K. Kash, C. E. Zah, R. Bhat, and S. L. Chuang [Appl. Phys. Lett. 62, 166 (1993)].

FOUR-WAVE MIXING IN SEMICONDUCTOR TRAVELING-WAVE AMPLIFIERS FOR WAVELENGTH CONVERSION IN ALL-OPTICAL NETWORKS

Intraband modulation in semiconductor gain media has recently been shown to provide a wideband nonlinearity which is five orders of magnitude larger than the Kerr non-linearity in silica fiber. We discuss recent work on the application of this nonlinearity to the wavelength conversion function in all optical networks; specifically, carrier wavelength spectral translation by four-wave mixing. In addition to reviewing the current performance of these devices including conversion efficiency, signal-to-noise and a simple system demonstration, we will describe the underlying physics of the ultra-fast four-wave mixing mechanism and its application to TeraHertz spectroscopy of intraband scattering. An overview of wavelength conversion in the context of all-optical networks is provided and competing techniques to four-wave mixing wavelength conversion are also discussed.

Time-resolved Spectral Analysis Of Phase Conjugation By Four-wave Mixing In Semiconductor Optical Amplifiers

Optical phase conjugation provides a mechanism for achieving dispersion compensation in optical fibers. This has been demonstrated by four-wave mixing (FWM) in both fiber and semiconductor optical amplifiers (SOAs). Imperfect phase conjugation will prevent exact reconstruction of a dispersed data stream. Here we use time-resolved spectral analysis (TRSA) to evaluate the performance of FWM in SOAs for phase conjugation.

Wavelength conversion by four-wave mixing in semiconductor optical amplifiers

Time-resolved spectral analysis is performed on 10 Gb/s signals wavelength converted by four-wave mixing (FWM) in semiconductor optical amplifiers. A pattern-dependent chirp resulting from parasitic gain modulation by the signal is measured and characterized as a function of the converters pump-to-probe ratio. This chirp is found to be insignificant for pump-to-probe ratios exceeding 9 dB.

Cross talk penalty in two-channel wavelength conversion by four-wave mixing in a strained semiconductor optical amplifier

A crucial function in wavelength-division multiplexed (WDM) all-optical networks is a wavelength converter. This function enhances wavelength routing options and improves network reconfigurability. Here we present a systematic study of the cross talk penalty as a function of the pump-to-signal power ratio for two 2.5-Gbit/s ASK channels separated by 1.5 nm.