Small displacement evaluation by a highly-coherent tunable laser referenced to stabilized femtosecond comb

0422388 - ÚPT 2014 ME eng A - Abstrakt
Číp, Ondřej - Šmíd, Radek - Hrabina, Jan - Čížek, Martin - Hucl, Václav - Lešundák, Adam - Holá, Miroslava - Růžička, Bohdan - Lazar, Josef
Small displacement evaluation by a highly-coherent tunable laser referenced to stabilized femtosecond comb.
21th annual International Conference on Advanced Laser Technologies ALT´13. Book of Abstracts. Budva: University of Montenegro, 2013. s. 51.
[ALT´13. Annual International Conference on Advanced Laser Technologies /21./. 16.09.2013-20.09.2013, Budva]
Grant CEP: GA ČR GAP102/10/1813; GA MŠMT ED0017/01/01; GA MŠMT EE2.4.31.0016
Institucionální podpora: RVO:68081731
Klíčová slova: passive optical resonator * highly-coherent tunable laser * femtosecond comb
Kód oboru RIV: BH - Optika, masery a lasery

The work describes the method for precise detection of length changes by a passive optical resonator working as a length sensor. The method is based on spectroscopy technique where a highly-coherent tuneable laser working at 1541 nm is locked to a selected mode of the optical resonator comb spectrum. Thus, the length change of the resonator is transformed to change of the optical frequency of the laser during the measuring process. The length of the resonator is kept by a spacer made from an ultra low expansion ceramic. If a temperature cycling of the spacer inserted in a vacuum chamber is done then the inspection of the coefficient of thermal expansion (CTE) of the ceramic is possible. The optical frequency of the tuneable laser identifies the length changes of the spacer during the temperature cycling. A precise detection of the optical frequency of the tuneable laser is required at kHz level. A down conversion processing must be applied to transfer the optical frequency to radiofrequency domain. Measurement of a beat-note signal between this laser and an optical frequency synthesizer - femtosecond comb solves this task well. In this case, the beat-note is detected with a period of repetition rate of the femtosecond comb laser. The described method is able to detect changes of the length in subnanometer level but with the range of micrometers. The work presents measured data of CTE and some records of measured beat-notes during the temperature cycling of the spacer.
Trvalý link: http://hdl.handle.net/11104/0228531