Werle P, Slemr F, Gehrtz M, Bräuchle C
Appl Opt. 1989 May 1;28(9):1638-42. doi: 10.1364/AO.28.001638.
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/f 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/f 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.
已测量了PbEuSe分子束外延二极管激光器高达500 MHz的宽带噪声特性。对于这种特定的激光器，发现与频率相关的（1/f型）激光噪声贡献的截止频率为170 MHz。如所证明的，在该截止频率以上，光子散粒噪声占主导。与1 MHz以下的1/f噪声主导区域相比，在散粒噪声受限区域观察到噪声降低了两个多数量级。这一发现表明，当应用频率调制技术而非1 MHz以下更传统的导数调制时，可调谐二极管激光吸收光谱法可实现类似的两个数量级的灵敏度提高。
