Noise Suppression on the Tunable Laser for Precise Cavity Length Displacement Measurement

Sensors

Radek Šmíd¹  Ondřej Číp¹  Jan Hrabina¹  Břetislav Mikel¹  Martin Čížek¹  Josef Lazar¹ 

[1] Institute of Scientific Instruments of Academy of Sciences of Czech Republic, v.v.i., Brno 61264, Czech Republic;

关键词: Fabry-Perot cavity;    unbalance Michelson interferometer;    noise suppression;    heterodyne interferometry;    displacement measurement;   

DOI  :  10.3390/s16091428

来源: DOAJ

【 摘 要 】

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− 9that corresponds to 0.3 nm (sub-nm) for 0.178 m long cavity with ability of displacement measurement of 0.5 mm.

【 授权许可】

Unknown