title: Widely tunable laser frequency offset lock with 30 GHz range and 5 THz offset.
abstract: We demonstrate a simple and versatile method to greatly extend the tuning range of optical frequency shifting devices, such as acousto-optic modulators (AOMs). We use this method to stabilize the frequency of a tunable narrow-band continuous-wave (CW) laser to a transmission maximum of an external Fabry-Perot interferometer (FPI) with a tunable frequency offset. This is achieved through a servo loop which contains an in-loop AOM for simple radiofrequency (RF) tuning of the optical frequency over the full 30 GHz mode-hop-free tuning range of the CW laser. By stabilizing the length of the FPI to a stabilized helium-neon (HeNe) laser (at 5 THz offset from the tunable laser) we simultaneously transfer the ~ 1 MHz absolute frequency stability of the HeNe laser to the entire 30 GHz range of the tunable laser. Thus, our method allows simple, wide-range, fast and reproducible optical frequency tuning and absolute optical frequency measurements through RF electronics, which is here demonstrated by repeatedly recording a 27-GHz-wide molecular iodine spectrum at scan rates up to 500 MHz/s. General technical aspects that determine the performance of the method are discussed in detail.
authors.affiliation: Department of Physics and Astronomy, LaserLaB VU University, De Boelelaan 1081, 1081 HV Amsterdam, The Netherlands.
authors.forename: J
authors.initials: J
authors.lastname: Biesheuvel
authors.forename: D W E
authors.initials: DW
authors.lastname: Noom
authors.forename: E J
authors.initials: EJ
authors.lastname: Salumbides
authors.forename: K T
authors.initials: KT
authors.lastname: Sheridan
authors.forename: W
authors.initials: W
authors.lastname: Ubachs
authors.forename: J C J
authors.initials: JC
authors.lastname: Koelemeij
mesh_terms: D004867:Equipment Design; D019544:Equipment Failure Analysis; D005246:Feedback; D007368:Interferometry / Q000295:instrumentation*; D007834:Lasers; D008872:Microwaves; D055053:Terahertz Radiation