FREE subscription
Subscribe for free to receive each issue of Semiconductor Today magazine and weekly news brief.





























5 January 2007


Bookham issued with US patent for tunable laser

Optical component, module and subsystem maker Bookham Inc of San Jose, CA, USA, has been issued US patent no. 7145923 for its DS-DBR (digital supermode-distributed Bragg reflector) laser, which underpins the firm's portfolio of tunable laser technology. The patent is one of several covering aspects of Bookham's tunable product range, and specifically protects its unique, monolithic, widely tunable laser design.

In the DS-DBR laser design, a multi-contact chirped grating is used in conjunction with a grating that produces a comb of reflective peaks to give a broad tuning range. By tuning portions of the chirped grating to overlap in wavelength, a single peak from the comb can be selected to determine the lasing wavelength. Fine tuning of the laser wavelength can be achieved by injecting current into both gratings. By selecting peaks sequentially, tuning can be achieved over the full range.

"Using the technology encapsulated in this patent, Bookham has developed wideband, InP-based tunable lasers for both C-band and L-band operation with very fast tuning times and with excellent output powers, spectral purity and reliability," says Andy Carter, vice president R&D. "This DS-DBR laser design also provides a route towards further photonic integration, promising increased functionality on a single InP chip, with the obvious benefits of low cost and small device size."

Bookham's DS-DBR technology is at the heart of its portfolio of LambdaFlex tunable technology products, including an integrable tunable laser assembly (iTLA), and two new products, both of which Bookham believes to be the first
of their kind. The wideband tunable transmitter assembly module (TTA) targets long-haul and regional metro applications and co-packages the wideband tunable laser with an InP Mach-Zehnder (MZ) modulator to provide
transmitter functionality in a cost-effective, small, iTLA-sized footprint package. The tunable DS-DBR and InP MZ technologies are also being incorporated into a small-form-factor (SFF) 300-pin Wideband Tunable Transponder.

Bookham's DS-DBR laser.