We describe wavelength-routed switching technology for 25-Gbit/s optical packets using a tunable transmitter that monolithically integrates a parallel-ring-resonator tunable laser and an InGaAlAs electro-absorption modulator (EAM). The transmitter provided accurate wavelength tunability with 100-GHz spacing and small output power variation. A 25-Gbit/s burst-mode optical-packet data was encoded onto the laser output by modulating the integrated EAM with a constant voltage swing of 2 V at 45$^{circ}$C. Clear eye openings were observed at the output of the 100 GHz-spaced arrayed-waveguide grating with error-free operation being achieved for all packets. The tunable transmitter is very promising for realizing a high-speed, large-port-count and energy-efficient wavelength-routing switch that enables the forwarding of 100-Gbit/s optical packets.

The recent progress of the performance of a CMOS-LSI is rapid and continuous, and the required bandwidth for communication between chips will be enormous. Dense optical interconnects by smart pixels may be used to such an application because it would have enough bandwidth and short delay of signaling. On-chip and chip-to-chip optical interconnects and electrical interconnects were compared and the advantages of the use of optics were indicated. For on-chip communication, high-speed (70% of the velocity of the light) propagation of signals by optical interconnects are useful and it enables whole chip synchronization. The considerable reduction of power dissipation using optics was estimated for chip-to-chip interconnects. The effect of hybrid integration with small parasitic capacitance was simulated and the sensitivity improvement of more than 13 dB was expected. How to fabricate a smart pixel is the most difficult subject. We had successfully fabricated smart pixels with VCSELs and PDs using polyimide bonding technique. CW lasing of the VCSEL was observed and it proved that the polyimide bonding technique was useful to making smart pixels. The integrated receiver was also fabricated in the same manner. It showed a high sensitivity of -9.2 dBm for a bit-rate of 622 Mbit/s. High-performance characteristics of the receiver resulted from the low parasitic integration with polyimide bonding technique.

Asynchronous optical packet switching (OPS) is a promising solution to support the continuous growth of transmission capacity demand. It has been, however, quite difficult to implement key functions needed at the node of such networks with all-optical approaches. We have proposed a new optoelectronic system composed of a packet-by-packet optical clock-pulse generator (OCG), an all-optical serial-to-parallel converter (SPC), a photonic parallel-to-serial converter (PSC), and CMOS circuitry. The system makes it possible to carry out various required functions such as buffering (random access memory), optical packet compression/decompression, and optical label swapping for high-speed asynchronous optical packets.

An optoelectronic 32-bit serial-to-parallel converter with a novel conversion scheme and shared-trigger configuration has been developed for the label processing of 100-Gbps (25-Gbps $ imes 4 lambda)$ optical packets. No external optical trigger source is required to operate the converter, as the optical packet itself is used to perform self-triggering. Compared to prior optoelectronic label converters, the new device has a much higher gain even while converting labels at higher data rates, and exhibits tolerance to the voltage swing of received packets. The device response is presented together with the experimental demonstration of serial-to-parallel conversion for 4 different labels at 25 Gbps.

We propose a burst optical packet generator based on a novel photonic parallel-to-serial conversion scheme, and demonstrate 40-Gbit/s 16-bit optical packet generation from 16-ch parallel low-voltage TTL data streams. It consists of electrical 4:1 parallel-to-serial converters that employ InP metal-semiconductor-metal photodetectors, and an optical time-domain multiplexer with electroabsorption modulators. The proposed optical packet generator is suitable for burst optical packet generation and overcomes the electronic bandwidth limitation, which is prerequisite for achieving high-speed photonic packet switched networks. In addition, it can be driven by simple low-cost low-power CMOS logic circuits, and is compact and extensible in terms of the number of input channels due to the effective combination of electrical and optical multiplexing.