A. Bhardwaj

Optical switch fabrics for ultra-high-capacity IP routers

Next-generation switches and routers may rely on optical switch fabrics to overcome scalability problems that arise in sizing traditional electrical backplanes into the terabit regime. In this paper, we present and discuss several optical switch fabric technologies. We describe a promising approach based on arrayed waveguide gratings and fast wavelength tuning and explain the challenges with respect to technical and commercial viability. Finally, we demonstrate an optical switch fabric capable of 1.2-Tb/s throughput and show packet switching with four ports running at 40 Gb/s each.

Reduced Recovery Time Semiconductor Optical Amplifier Using p-Type-Doped Multiple Quantum Wells

The effect of p-type doping of the active region of multiple quantum-well (MQW) semiconductor optical amplifiers (SOAs) has been studied. Spectrogram measurements of the dynamics of the SOAs reveal that using p-doped barriers for the MQWs has significantly reduced both gain and phase recovery times. 1/e phase recovery times as short as 11 ps were demonstrated using this approach

Fast switching characteristics of a widely tunable laser transmitter

We demonstrate a widely tunable laser transmitter that accesses 32 ITU channels with 100-GHz spacing and switches between all channel combinations in less than 45 ns. The compact module uses commercially available electronic components. We investigate the electrical and thermal properties of the laser and the tuning section driver. The experiments show that a low output impedance driver circuit produces faster switching times. Also, temperature variation of the laser limits the wavelength accuracy of the switching. Finally, we present the correlation between switching times and the laser tuning currents.

Demonstration of a 1.2 Tb/s optical packet switch fabric (32/spl times/40 Gb/s) based on 40 Gb/s burst-mode clock-data-recovery, fast tunable lasers, and a high-performance N/spl times/N AWG

We demonstrate a 1.2 Tb/s optical packet switch fabric based on burst-mode clock-data-recovery at 40 Gb/s with packet separations of up to 400 ns and lock times under 5 ns fast wavelength switching between 32 channels in less than 46 ns and a 42/spl times/42 AWG (array waveguide grating) with a worst-case loss of 4.2 dB.

Fast packet routing in a 2.5 Tb/s optical switch fabric with 40 Gb/s duobinary signals at 0.8 b/s/Hz spectral efficiency

We demonstrate error-free 40 Gb/s duobinary packet routing by fast wavelength switching on two ports in a 64/spl times/64 passive optical switch fabric. Switching in less than 45 ns for all channel combinations and burst-mode clock recovery in less than 15 ns are achieved.

Reduction of nonlinear distortion from a semiconductor optical amplifier using an optical equalizer

We demonstrate significant improvement in the measured bit-error rates of 40-Gb/s signals distorted after passing through a saturated semiconductor optical amplifier (SOA) by using a simple colorless general optical equalizer. The optical equalizer reduces the overshoots arising from the nonlinear gain dynamics of the SOA and improves the opening of the eye. We study the improvement in receiver sensitivity by using the equalizer while varying the optical power and wavelength at the input of the SOA.

Significant reduction of recovery time in semiconductor optical amplifier using p type modulation doped MQW

The effect of p-type doping of the barriers of multiple quantum well semiconductor optical amplifiers is shown to significantly reduce the gain and carrier recovery times with phase recovery times as short as 11ps.

Optical Equalizer monolithically integrated with a Semiconductor Optical Amplifier

We present the first optical equalizer monolithically integrated with a semiconductor optical amplifier. We show that the device can mitigate the Inter-Symbol Interference arising from narrowband optical filtering on 40 Gb/s Non-Return to Zero data.