W. Conard Holton
The sampled-grating distributed-Bragg-reflector (DBR) tunable laser is a strong contender to act as a spare transmitter or for optical routing and switching (see also p. 24). Researchers at Agility Communications (Santa Barbara, CA), working with colleagues at the University of California, Santa Barbara, have demonstrated a new variation that integrates a semiconductor optical amplifier (SOA) with the sampled-grating DBR laser. They had previously integrated the laser with an electroabsorption modulator.
In their latest prototype, the researchers have added a curved passive output guide and antireflective coating at the output of the amplifier. The guide acts as an angled facet that reduces reflectivity across the entire 50-nm tuning range of the laser (see figure). The low residual reflectivity from the facet enables the device to maintain a high side-mode-suppression ratio at relatively high amplifier gains. The researchers calculated the unity gain current at 1550 nm to be 14 mA and the peak gain to be 8.5 dB at 150 mA. A recent startup, Agility claims that the simple architecture of its integrated lasers makes them very easy and cost-effective to manufacture, especially given that the monolithic integration of components eliminates the need for expensive devices such as external modulators. Greg Fish, director of device engineering at Agility said, "We`re in the development phase now and should have real products by the end of this year." For more information, contact Greg Fish at email@example.com.
An integrated sampled-grating DBR laser and SOA device structure is tunable over a 50-nm tuning range in the 1550-nm region. The SOA provides increased output power and proved wavelength stability.