Bookham Demos 40-Gb/s Chip

Bookham Inc. announced it has developed and demonstrated an ultrasmall, 5-mm, 40-Gb/s optical differential quadrature phase-shift-keying modulator chip, implemented through proprietary indium phosphide Mach-Zehnder (InP MZ) technology for use in the 40-Gb/s market.

Bookham said the smaller InP MZ platform will allow it to offer 40-Gb/s products in smaller footprints, compared to existing 40-Gb/s systems that use larger optics. It said the InP TL5000 wideband tunable iTLA has been proven for use in both 10 and 40-Gb/s systems.

The company said it is now combining the tunable laser with 40-Gb/s MZ modulator chips from its UK 3-in wafer fab to demonstrate innovation in the 40-Gb/s application space.

"The capability to offer high-bit-rate performance with our fully qualified, proven tunable laser and InP MZ modulator is crucial as vendors continue to evolve toward 40-Gb/s networks," said Adam Price, PLM (pump laser module) director at Bookham. "40-Gb/s rollout is still hampered by prohibitive pricing as we see 40 Gb/s systems costing in excess of 10 times a 10-Gb/s system. With our vertically integrated InP core technology and strength in the 10-Gb/s market, we are able to drive significant disruption in order to enable 40-Gb/s systems to be adopted at a cost point that allows widespread adoption. The InP MZ platform has the flexibility to implement a range of modulation schemes at 40Gb/s, but it is our vision that ODQPSK, in which we have significant intellectual property, is the modulation format to allow the correct price positioning at 40 Gb/s, and the scalability to 100 Gb/s.

"ODQPSK also allows 40 Gb/s to be deployed onto a 50-GHz grid and demonstrates higher resilience to polarization mode dispersion," Price said. "We have a proven InP capability to allow parallel modulator chip architectures to be implemented for the 40-Gb/s approach and have produced an InP ODQPSK chip structure that is only 5-mm long. Traditional LiNbO3 technology, which uses discrete modulators coupled together to form parallel structures, cannot compete with production simplicity and footprint size."
Bookham is showing the LambdaFLEXT range of tunable products at OFC/NFOEC (Booth 1334), being held this week in San Diego.