Single frequency laser diodes, DBR or DFB?

The DBR laser architecture consists of an electrically pumped gain region and a separate passive DBR grating region, monolithically fabricated over a ridge waveguide.

The DBR is often compared to the Distributed Feedback (DFB) laser that is used for low power telecommunication laser applications. They both have the common elements of a Bragg grating and a ridge waveguide to achieve a single frequency output beam, however their architectures and fabrication techniques are different. Whereas a DFB uses a weakly reflective grating running the full length of the gain ridge to achieve a select mode, the DBR has a relatively short, highly reflective, unpumped Bragg reflector to select a single longitudinal mode. These differing architectures lead to performance differences.

DBR lasers offer high power, reliability, low noise, narrow linewidth, and stable operating characteristics, as a result of the single growth epi and separate passive DBR region.

Features of the DBR are: high power, single frequency, linewidth typically below 1MHz, temperature tuneable, nano or picosecond pulse capability and wavelengths from 775nm to 1085nm.

Applications include atomic clocks, magnetometers, gravimeters, gyroscopes, quantum computing, time-resolved fluorescence spectroscopy, terahertz generation, range-finding / targeting and more.