A compact laser head with high-frequency stability for Rb atomic clocks and optical instrumentation

Abstract

We present a compact and frequency-stabilized laser head based on an extended-cavity diode laser. The laser head occupies a volume of 200 cm 3 and includes frequency stabilization to Doppler-free saturated absorption resonances on the hyperfine components of the 87 Rb D 2 lines at 780 nm, obtained from a simple and compact spectroscopic setup using a 2 cm 3 vapor cell. The measured frequency stability is ഛ2 ϫ 10 −12 over integration times from 1 s to 1 day and shows the potential to reach 2 ϫ 10 −13 over 10 2 −10 5 s. Compact laser sources with these performances are of great interest for applications in gas-cell atomic frequency standards, atomic magnetometers, interferometers and other instruments requiring stable and narrow-band optical sources.

Diode laser frequency stabilisation for water-vapour differential absorption sensing

“…This Rb laser was stable to 2 × 10 −12 (i.e. less than 1 kHz) over integration times between 1 s and 1 day [18]. The wavemeter output was recorded with an integration time of 1 s during 90 h. The results are reported in Fig.…”

“…Each laser type offers some advantages but also has some drawbacks compared to the other for implementation in the reference system. The ECDLs, designed from a stabilised laser head that was previously developed for Rb atomic clocks [18], can be tuned over more than 35 nm with a mode-hop-free tuning range of 10 GHz. On the other hand, the DFB lasers are intrinsically single mode with a large mode-hop-free tuning range of several nanometres, but the tuning range around their operation central wavelength is small in comparison to that of an ECDL.…”

Stabilizing a Fabry–Perot Etalon Peak to 3 cm s-1for Spectrograph Calibration

“…The most important of these are pump beam intensity, angle between the pump and probe beams, Rb cell temperature, and ambient magnetic field. Affolderbach & Mileti (2005) measured the line shifts due to these parameters using a setup similar to ours and demonstrated sufficient control of all of them to achieve <2 × 10 À12 relative frequency stability of an ECDL locked to the Rb D 2 line over timescales ≥10 4 s. Controlling all above mentioned shifts sufficiently well to guarantee stability and reproducibility of the Rb frequency at the level of precision needed for calibration is relatively straightforward, for example by surrounding the Rb cell with a single layer of mu-metal and actively stabilizing the cell temperature and pump laser power.…”

“…The advantage of this method is its simplicity: To our knowledge, this is the only scheme that does not require locking the laser to the Rb transition and then locking the etalon to the laser. While more sophisticated setups provide higher precision, with stabilities of <10 À12 (Ye et al 1996;Affolderbach & Mileti 2005), we adapted our method to the precision requirements of RV studies. Removing the added complexity and hardware necessary for other stabilization methods maximizes reliability and makes for a cost-effective solution that is easy to set up, making our instrument well suited for an observatory environment.…”

“…We use saturated absorption spectroscopy to stabilize one transmission peak of a broadband etalon to a hyperfine transition of rubidium. The rubidium transition is widely used as a frequency standard, which has been utilized to stabilize lasers to relative precisions of <10 À12 (Ye et al 1996;Affolderbach & Mileti 2005); it provides an ideal, repeatable, and stable wavelength reference. Our locking scheme is simple and robust and will work for a wide variety of etalons operating in the visible and near-infrared (NIR).…”