Šmíd Radek, Čížek Martin, Mikel Břetislav, Hrabina Jan, Lazar Josef, Číp Ondřej
Institute of Scientific Instruments of Academy of Sciences of Czech Republic, v.v.i., Brno 61264, Czech Republic.
Sensors (Basel). 2016 Sep 6;16(9):1428. doi: 10.3390/s16091428.
The absolute distance between the mirrors of a Fabry-Perot cavity with a spacer from an ultra low expansion material was measured by an ultra wide tunable laser diode. The DFB laser diode working at 1542 nm with 1.5 MHz linewidth and 2 nm tuning range has been suppressed with an unbalanced heterodyne fiber interferometer. The frequency noise of laser has been suppressed by 40 dB across the Fourier frequency range 30-300 Hz and by 20 dB up to 4 kHz and the linewidth of the laser below 300 kHz. The relative resolution of the measurement was 10 - 9 that corresponds to 0.3 nm (sub-nm) for 0.178 m long cavity with ability of displacement measurement of 0.5 mm.
使用超宽可调谐激光二极管测量了由超低膨胀材料制成的带间隔层的法布里-珀罗腔中镜子之间的绝对距离。工作在1542nm、线宽为1.5MHz且调谐范围为2nm的分布反馈激光二极管已被不平衡外差光纤干涉仪抑制。在30 - 300Hz的傅里叶频率范围内，激光的频率噪声被抑制了40dB，在高达4kHz的频率范围内被抑制了20dB，并且激光的线宽低于300kHz。测量的相对分辨率为10⁻⁹，对于长度为0.178m的腔，这对应于0.3nm（亚纳米），并且具有0.5mm的位移测量能力。
