A novel discrete mode narrow linewidth laser diode for spectroscopic based gas sensing in the 1.5 μm region

The characteristics of a novel Discrete Mode laser diode are described with particular reference to its capability in spectroscopic based gas sensing. In this regard, its emission linewidth, Side Mode Suppression Ratio and tuneability are of particular note. The measured narrow linewidth of 550?kHz has applications with respect to spectrally narrow absorption features found, for example, in saturated absorption lines, in hyperfine structure of some rotational manifolds and in whispering gallery mode features associated with optical microspheres. Other notable measured characteristics show mode-hop-free temperature tuning of 11 nm at a linear tuning rate of 0.1 nm/°C and a Side Mode Suppression Ratio in the range 56 to 46 dB and a long term (72?hours) wavelength stability of 1?pm per day. In essence, this novel Discrete Mode laser displays excellent potential for diode laser based sensing applications in the near infrared.