17 Jun 2002
A high-powered tunable light source is set to play a key role in driving fiber-optic networks forward.
Courtesy of Fiber Systems International
A team of scientists at NEC's Photonic and Wireless Devices Research Laboratories in Japan has developed a high-power tunable light source that covers 1530 to 1562 nm wavelengths, the entire telecoms C-band.
These sources are likely to play an important role in dense wavelength-division multiplexing networks as channel-adjustable transmitters or as cost-effective replacement parts.
NEC's design consists of monolithically integrated four-microarray distributed-feedback laser diodes, a multimode interference optical coupler and a semiconductor optical amplifier. The chip size is just 0.77 mm2.
Each device has a tuning range of 8 nm - controlled by varying the temperature from 15 to 40 °C using a thermoelectric cooler - and gives a fiber-coupled output power of more than 8.5 mW.
A technique called atmospheric-pressure microarray-selective-epitaxy was used to simultaneously fabricate five of these devices, each with a different tuning range, onto a single chip. Together, the five sources cover 40 x 100 GHz spaced channels from 1530 to 1562 nm.
The device also boasts a threshold current of 8.3 ± 1.2 mA at 25 °C and a sidemode suppression ratio of more than 45 dB.
Tami Freeman is a contributing writer for Fiber Systems International.