The narrow-band tuneable optical filter for beat-note detection between single-frequency and mode-locked laser

0426195 - ÚPT 2015 ME eng A - Abstract
Růžička, Bohdan - Číp, Ondřej - Šmíd, Radek - Hrabina, Jan - Čížek, Martin - Hucl, Václav - Lešundák, Adam - Holá, Miroslava - Lazar, Josef - Mikel, Břetislav
The narrow-band tuneable optical filter for beat-note detection between single-frequency and mode-locked laser.
21th annual International Conference on Advanced Laser Technologies ALT´13. Book of Abstracts. Budva: University of Montenegro, 2013. s. 55.
[ALT´13. Annual International Conference on Advanced Laser Technologies /21./. 16.09.2013-20.09.2013, Budva]
R&D Projects: GA ČR GAP102/10/1813; GA MŠMT ED0017/01/01; GA MŠMT EE2.4.31.0016
Institutional support: RVO:68081731
Keywords : narrow-band tuneable optical filter * mode-locked laser
Subject RIV: BH - Optics, Masers, Lasers

Some spectroscopic applications use an optical mixing of a single frequency tuneable laser and a femtosecond mode-locked laser when a precise value of the optical frequency of the tuneable laser has to be detected. The mode-locked laser has a broadband optical frequency spectrum which consists of thousands frequency modes (teeth). They are placed in an equidistant frequency spacing determined by a repetition frequency of femtosecond pulses, typically hundreds of MHz. When the optical mixing is done between this mode-locked laser and the single frequency one, the beat-note radiofrequency spectrum in the output of a photo detector is completely overloaded by many beat-notes came from mixing of the mode-locked laser modes themselves. This problem can be solved only by an optical filtering where frequency modes of the mode-locked laser farer from the single-frequency laser frequency are suppressed. Then only a small group of mode-locked laser modes is optically mixed between them. Our work presents an experimental setup with a fibre Bragg grating as the filter where only the narrow-band optical spectrum from the mode-locked laser is reflected to the beat-note processing with the single frequency laser. The grating has temperature control to change the reflecting optical frequency bandwidth to the desired value where the single-frequency laser operates. Examples of detected beat-notes are presented and evaluated.
Permanent Link: http://hdl.handle.net/11104/0235682