Inuk Kang

Simultaneous temporal characterization of telecommunication optical pulses and modulators by use of spectrograms.

We demonstrate a simple technique for simultaneous and complete characterization of the optical pulses and temporal modulators commonly used in telecommunication. The electric field of a pulse and the response of a modulator are obtained from the analysis of the two-dimensional spectrogram of the pulse gated by the modulator. The measurement sensitivity is greatly improved compared with the conventional nonlinear optical techniques. Trains of picosecond pulses as weak as 10(-17)J are accurately characterized with an electroabsorption modulator as the temporal gate. The time-resolved transmission and phase of the modulator are also presented.

Complete temporal characterization of short optical pulses by simplified chronocyclic tomography

A new self-referencing technique to characterize the temporal electric field of a short optical pulse is presented. The group delay of the pulse is directly obtained from two projections of the Wigner-Ville function after rotation of the pulse in chronocyclic space. Implementation of the technique requires only quadratic temporal phase modulation and two spectrum measurements, from which the electric field is directly and unambiguously reconstructed without any assumption. A device based on these principles is used to characterize the electric field of a 2-ps optical pulse.

Experimental test of dense wavelength-division multiplexing using novel, periodic-group-delay-complemented dispersion compensation and dispersion-managed solitons.

In an all-Raman amplified, recirculating loop containing 100-km spans, we have tested dense wavelength-division multiplexing at 10 Gbits/s per channel, using dispersion-managed solitons and a novel, periodic-group-delay-complemented dispersion-compensation scheme that greatly reduces the timing jitter from interchannel collisions. The achieved working distances are approximately 9000 and approximately 20,000 km for uncorrected bit error rates of <10(-8) and <10(-3), respectively, the latter corresponding to the use of enhanced forward error correction; significantly, these distances are very close to those achievable in single-channel transmission in the same system.

Implementation of electro-optic spectral shearing interferometry for ultrashort pulse characterization

Electro-optic spectral shearing interferometry is implemented for the highly sensitive characterization of ultrashort pulses from a free-running source. A simple phase-locked-loop clock recovery circuit is used to extract the high-frequency microwave clock signal to drive the phase modulator for spectral shearing. We demonstrate accurate full temporal characterization of 200-fs pulses from an optical parametric oscillator at 5-pW average power.

A Programmable 8-bit Optical Correlator Filter for Optical Bit Pattern Recognition

We demonstrate a compact reconfigurable 8-bit optical matching filter fabricated using 4% delta high-index-contrast silica-on-silicon waveguides. This planar lightwave circuit is based on an eighth-order tap-and-delay finite impulse response architecture. Multimode interference-based splitters/combiners along with variable optical attenuators and phase shifters allow us to tune and dynamically reconfigure all the taps and delays (filter coefficients) in the filter using a simple automated algorithm. The filter is designed to recognize 8-bit patterns in 40-Gb/s data streams and we demonstrate its working principle by successfully correlating 8-bit binary phase-shift-keyed patterns.

Highly sensitive differential tomographic technique for real-time ultrashort pulse characterization.

We present a highly sensitive real-time optical pulse characterization technique based on differential chronocyclic tomography. Sub 10-/spl mu/W sensitivity and update rates up to 66 Hz are demonstrated.

Interferometric Operation of an Electroabsorption Modulator for PSK Modulation and OOK Modulation with Performance Enhancements

We present interferometric operation of an electroabsorption modulator. We demonstrate 40-Gb/s PSK modulation, and up to 8.7 dB improvement in extinction ratio in 40-Gb/s OOK modulation with 0.8V driving voltage using a single electroabsorption modulator.

Integrated Photonic Devices for All-Optical Signal Processing

High-speed all-optical signal processing is promising for applications where high throughput and low latency are required. We report recent progresses in developing hybrid photonic-integrated devices for all-optical signal processing.

High-speed all-optical signal processing using semiconductor optical amplifiers

We present semiconductor optical amplifier-based optical signal processing for high bit-rate optical communication. All optical wavelength conversion and logic operation of 40-Gb/s PSK and OOK signals are demonstrated. High-speed all-optical signal characterization methods and the application to all-optical signal processing are also presented.