Laser frequency stabilization using a transfer interferometer

Abstract

We present a laser frequency stabilization system that uses a transfer interferometer to stabilize slave lasers to a reference laser. Our implementation uses off-the-shelf optical components along with microcontroller-based digital feedback, and offers a simple, flexible, and robust way to stabilize multiple laser frequencies to better than 1 MHz.

Nd+ isotope shift measurements in a cryogenically cooled neutral plasma

“…External-cavity diode lasers (ECDLs) were used for spectroscopy of the 399 nm and 397 nm transitions. A portion of the light from each ECDL was sent to a wavemeter for coarse wavelength measurements, and to a transfer interferometer for frequency stabilization [31]. Nd + ion clouds were produced by pulsed Nd:YAG laser ablation of a neodymium metal target, and cooled by collisions with helium buffer gas within a cryogenically-cooled cell [24].…”

“…During the experiment, both lasers were simultaneously locked to the transfer interferometer (with long-term instability below 1 MHz) [31]. The frequency of one of the lasers ("probe") was scanned across the different isotope resonances, by adjusting the phase of the interferometer signal.…”

“…detailed description of this method can be found in Ref. [31].) The lock point phase could be varied digitally to scan the frequency of the laser.…”

Cold, dense, atomic ion clouds produced by cryogenic buffer-gas cooling

“…Ca + ions were probed using the 4s 2 S 1/2 → 4p 2 P 1/2 transition, and Dy + ions using the 4f 10 6s 1/2 (J = 17/2) → 4f 10 6p (J = 15/2) transition (both near 397 nm). The frequency of the 397 nm probe laser was locked (typically with 1 MHz instability) to a cesium-stabilized reference laser using a transfer interferometer [22], and scanned under software control. Photodiode signals were processed to extract the optical depth at both the "near" and "far" measurement ports shown in Fig.…”

A simple and low-cost setup for part per billion level frequency stabilization and characterization of red He-Ne laser

“…Having a simple, low cost frequency reference with part per billion level stability is of great value in such scenarios. For example, this can serve as a frequency reference in the so called transfer cavity method [3,4], used for frequency stabilization of lasers operating over a wide range of wavelengths. Here, a stabilized laser (like He-Ne) acts as a frequency reference for a scanning Fabry Perot cavity, which can then be used to lock another laser operating at a different frequency.…”