Characteristics of linewidth-narrowed distributed Bragg reflector lasers with a fiber external cavity formed with the vertical grating emission

Linewidth reduction has been observed in a distributed Bragg reflector (DBR) laser with a second-order grating when an external cavity is formed with the vertical emission. The external cavity consists of a length of optical fiber which is brought close to the top of the laser. Displayed linewidths as low as 26 kHz have been measured. To the authors' knowledge, this is the first report of linewidth reduction via vertical emission from a laser diode.<
>