The wideband noise characteristics of a PbEuSe molecular beam epitaxy diode laser have been measured up to 500 MHz. The cutoff of the frequency dependent (1/ƒ type) laser noise contribution was found to be 170 MHz for this particular laser. Above this cutoff frequency the photon shot noise dominates, as was demonstrated. A noise reduction of more than 2 orders of magnitude was observed in the shot noise limited domain when compared with the 1/ƒ noise dominated region below 1 MHz. This finding indicates that a similar 2 orders of magnitude sensitivity improvement can be achieved in tunable diode laser absorption spectroscopy when frequency modulation techniques are applied instead of the more conventional derivative modulation below 1 MHz.
© 1989 Optical Society of America
Peter Werle, Franz Slemr, Manfred Gehrtz, and Christof Bräuchle, "Wideband noise characteristics of a lead-salt diode laser: possibility of quantum noise limited TDLAS performance," Appl. Opt. 28, 1638-1642 (1989)