All-optical wavelength conversion for 10 Gb/s DPSK signals in a silicon ring resonator.

We demonstrate all-optical wavelength conversion at 10 Gb/s for differential phase-shift keyed (DPSK) data signals in the C-band, based on four-wave mixing (FWM) in a silicon ring resonator. Error-free operation with a system penalty of ~4.1 dB at 10⁻9 BER is achieved.

All-optical XOR logic gate for 40Gb/s DPSK signals via FWM in a silicon nanowire.

We demonstrate an all-optical XOR logic function for 40Gb/s differential phase-shift keyed (DPSK) data signals in the C-band, based on four-wave mixing (FWM) in a silicon nanowire. Error-free operation with a system penalty of ~3.0dB and ~4.3dB at 10⁻9 BER is achieved.

Optical phase conjugation by an As(2)S(3) glass planar waveguide for dispersion-free transmission of WDM-DPSK signals over fiber.

We report the first demonstration of optical phase conjugation (OPC) transmission of phase encoded and wavelength-division multiplexed (WDM) signals by the Kerr effect in a planar structured waveguide. The phase conjugated electric field of the signal is produced by four wave mixing pumped by a CW laser during co-propagating with the signal in a highly nonlinear waveguide fabricated in As(2)S(3) glass. Experiments demonstrate the capability of the device to perform dispersion-free transmission through up to 225 km of standard single mode fiber for a 3 × 40 Gb/s WDM signal, with its channels encoded as return-to-zero differential phase shift keying and spaced either 100 or 200 GHz apart. This work represents an important milestone towards demonstrating advanced signal processing of high-speed and broadband optical signals in compact planar waveguides, with the potential for monolithic optical integration.

Photonic chip based transmitter optimization and receiver demultiplexing of a 1.28 Tbit/s OTDM signal.

We demonstrate chip-based Tbaud optical signal processing for all-optical performance monitoring, switching and demultiplexing based on the instantaneous Kerr nonlinearity in a dispersion-engineered As(2)S(3) planar waveguide. At the Tbaud transmitter, we use a THz bandwidth radio-frequency spectrum analyzer to perform all-optical performance monitoring and to optimize the optical time division multiplexing stages as well as mitigate impairments, for example, dispersion. At the Tbaud receiver, we demonstrate error-free demultiplexing of a 1.28 Tbit/s single wavelength, return-to-zero signal to 10 Gbit/s via four-wave mixing with negligible system penalty (< 0.5 dB). Excellent performance, including high four-wave mixing conversion efficiency and no indication of an error-floor, was achieved. Our results establish the feasibility of Tbaud signal processing using compact nonlinear planar waveguides for Tbit/s Ethernet applications.

Optical signal processing on a silicon chip at 640Gb/s using slow-light.

We demonstrate optical performance monitoring of in-band optical signal to noise ratio (OSNR) and residual dispersion, at bit rates of 40Gb/s, 160Gb/s and 640Gb/s, using slow-light enhanced optical third harmonic generation (THG) in a compact (80microm) dispersion engineered 2D silicon photonic crystal waveguide. We show that there is no intrinsic degradation in the enhancement of the signal processing at 640Gb/s relative to that at 40Gb/s, and that this device should operate well above 1Tb/s. This work represents a record 16-fold increase in processing speed for a silicon device, and opens the door for slow light to play a key role in ultra-high bandwidth telecommunications systems.

Error-free all-optical demultiplexing at 160Gb/s via FWM in a silicon nanowire.

We demonstrate all-optical time division demultiplexing from 160Gb/s to 10Gb/s in the C-band, based on four-wave mixing (FWM) in a silicon nanowire. We achieve error-free operation with a system penalty of approximately 3.9dB at 10(-9) BER.

Simultaneous multi-impairment monitoring of 640 Gb/s signals using photonic chip based RF spectrum analyzer.

We report the first demonstration of simultaneous multi-impairment monitoring at ultrahigh bitrates using a THz bandwidth photonic-chip-based radio-frequency (RF) spectrum analyzer. Our approach employs a 7 cm long, highly nonlinear (gamma approximately 9900 /W/km), dispersion engineered chalcogenide planar waveguide to capture the RF spectrum of an ultrafast 640 Gb/s signal, based on cross-phase modulation, from which we numerically retrieve the autocorrelation waveform. The relationship between the retrieved autocorrelation trace and signal impairments is exploited to simultaneously monitor dispersion, in-band optical signal to noise ratio (OSNR) and timing jitter from a single measurement. This novel approach also offers very high OSNR measurement dynamic range (> 30 dB) and is scalable to terabit data rates.

Terahertz bandwidth RF spectrum analysis of femtosecond pulses using a chalcogenide chip.

We report the first demonstration of the use of an RF spectrum analyser with multi-terahertz bandwidth to measure the properties of femtosecond optical pulses. A low distortion and broad measurement bandwidth of 2.78 THz (nearly two orders of magnitude greater than conventional opto-electronic analyzers) was achieved by using a 6 cm long As(2)S(3) chalcogenide waveguide designed for high Kerr nonlinearity and near zero dispersion. Measurements of pulses as short as 260 fs produced from a soliton-effect compressor reveal features not evident from the pulse's optical spectrum. We also applied an inverse Fourier transform numerically to the captured data to re-construct a time-domain waveform that resembled pulse measurement obtained from intensity autocorrelation.

High bit rate all-optical signal processing in a fiber photonic wire.

We report the first demonstration of high bit rate signal processing by a fiber-based photonic wire. We achieve 160 Gb/s demultiplexing via four wave mixing in a 1.9 microm diameter photonic wire tapered from As(2)S(3) chalcogenide glass single mode fibre, with very low pump power requirements ( < 20 mW average power, 0.45 W peak power), enabled by a very high nonlinearity (gamma approximately 7850 W(-1) km (-1) ) and greatly reduced dispersion.

Long, low loss etched As(2)S(3) chalcogenide waveguides for all-optical signal regeneration.

We report on the fabrication and optical properties of etched highly nonlinear As(2)S(3) chalcogenide planar rib waveguides with lengths up to 22.5 cm and optical losses as low as 0.05 dB/cm at 1550 nm - the lowest ever reported. We demonstrate strong spectral broadening of 1.2 ps pulses, in good agreement with simulations, and find that the ratio of nonlinearity and dispersion linearizes the pulse chirp, reducing the spectral oscillations caused by self-phase modulation alone. When combined with a spectrally offset band-pass filter, this gives rise to a nonlinear transfer function suitable for all-optical regeneration of high data rate signals.

Fourth-order dispersion suppression of ultrashort optical pulses by second-order dispersion and cosine phase modulation.

A technique for significantly suppressing severe fourth-order dispersion of ultrashort optical pulses in long-distance transmission is analyzed by use of the quadratic phase from the excess second-order dispersion of the fiber link in conjunction with synchronously applied cosine phase modulation of temporally stretched pulses. Numerical simulation predicts much improved transmission of 250-fs pulses at 5-10-GHz repetition rates over ~100 km of fiber by pi-3.5pi phase modulation.

High-sensitivity pulse spectrogram measurement using two-photon absorption in a semiconductor at 1.5-microm wavelength.

A femtosecond pulse characterization technique is developed using frequency-resolved optical gating based on the two-photon absorption in an InP crystal.The technique provides direct visual monitoring of pulse frequency chirping in the time-spectral domain for femtosecond pulses with a pulse energy as low as 3.8 pJ.Pulse chirping and pedestal wings of 10-GHz optical fiber solitons are characterized experimentally for the first time by this technique.