Two-Stage System Based on a Software-Defined Radio for Stabilizing of Optical Frequency Combs in Long-Term Experiments

0424308 - ÚPT 2014 RIV CH eng J - Článek v odborném periodiku
Čížek, Martin - Hucl, Václav - Hrabina, Jan - Šmíd, Radek - Mikel, Břetislav - Lazar, Josef - Číp, Ondřej
Two-Stage System Based on a Software-Defined Radio for Stabilizing of Optical Frequency Combs in Long-Term Experiments.
Sensors. Roč. 14, č. 1 (2014), s. 1757-1770. E-ISSN 1424-8220
Grant CEP: GA ČR GPP102/11/P819; GA ČR GAP102/10/1813; GA MŠMT ED0017/01/01; GA MŠMT EE2.4.31.0016
Institucionální podpora: RVO:68081731
Klíčová slova: optical frequency combs * digital signal processing * software-defined radio * beat note * stabilization * long-term operation
Kód oboru RIV: JA - Elektronika a optoelektronika, elektrotechnika
Impakt faktor: 2.245, rok: 2014

A passive optical resonator is a special sensor used for measurement of lengths on the nanometer and sub-nanometer scale. A stabilized optical frequency comb can provide an ultimate reference for measuring the wavelength of a tunable laser locked to the optical resonator. If we lock the repetition and offset frequencies of the comb to a high-grade radiofrequency (RF) oscillator its relative frequency stability is transferred from the RF to the optical frequency domain. Experiments in the field of precise length metrology of low-expansion materials are usually of long-term nature so it is required that the optical frequency comb stay in operation for an extended period of time. The optoelectronic closed-loop systems used for stabilization of combs are usually based on traditional analog electronic circuits processing signals from photodetectors. From an experimental point of view, these setups are very complicated and sensitive to ambient conditions, especially in the optical part, therefore maintaining long-time operation is not easy. The research presented in this paper deals with a novel approach based on digital signal processing and a software-defined radio. We describe digital signal processing algorithms intended for keeping the femtosecond optical comb in a long-time stable operation. This need arose during specialized experiments involving measurements of optical frequencies of tunable continuous-wave lasers. The resulting system is capable of keeping the comb in lock for an extensive period of time (8 days or more) with the relative stability better than 1.6 x 10-11.
Trvalý link: http://hdl.handle.net/11104/0230388