A phase-locked laser system based on double direct modulation technique for atom interferometry

Abstract

We demonstrate a Raman laser system based on phase modulation technology and phase feedback control. The two laser beams with frequency difference of 6.835 GHz are modulated using electro-optic and acousto-optic modulators, respectively. Parasitic frequency components produced by the electro-optic modulator are filtered using a Fabry-Perot Etalon. A straightforward phase feedback system restrains the phase noise induced by environmental perturbations. The phase noise of the laser system stays below -125 rad 2 /Hz at frequency offset higher than 500 kHz. Overall phase noise of the laser system is evaluated by calculating the contribution of the phase noise to the sensitivity limit of a gravimeter. The results reveal that the sensitivity limited by the phase noise of our laser system is lower than that of a state-of-art optical phase-lock loop scheme when a gravimeter operates at short pulse duration, which makes the laser system a promising option for our future application of atom interferometer.

Carrier-Suppressed Multiple Single-Sideband Laser Source for Atom Cooling and Interferometry

“…The tunability of the IQ modulator implies that our architecture can also be adapted for other atomic species, such as potassium [22] or cesium [45], or upgraded to operate with a single diode. The simplicity of our architecture, along with the dramatic improvement in accuracy over phase-modulatorbased designs, makes it a suitable alternative for systems employing two phase-locked lasers [20,21]. It is also easily transportable-making it ideal for a large range of onboard applications, including mobile gravity surveys [46], inertial navigation [18], or fundamental physics in Space [47].…”

“…Within the scope of all-fibered laser systems designed for laser cooling and atom interferometry, several configurations have been demonstrated. The use of two separate laser diodes, one operating at each frequency, requires an optical phase lock [20,21]. Frequency offset master-slave architectures offer real-time frequency agility by controlling the current of the slave diode [22], but are typically limited in bandwidth and dynamic range by the electronics.…”

Impact of Laser Frequency Noise in Coherent Population Trapping with Cold Atoms

“…With this approach, we are able to implement the linlin CPT scheme with a single laser source. This is an advantage for our long-term goal of developing a compact device, but this approach also introduces a significant source of phase noise due to the separated paths of the two CPT components [23]. In order to suppress this phase noise, we implement a phase-locked loop (PLL) by detecting the phase of the beatnote between the light from AOM 1 and the first-order sideband from the EOM and feeding back to our EOM driver.…”

“…One possible explanation is that some of the phase noise is actually due to laser frequency noise, which is converted to phase noise by the mismatched optical paths in Fig. 1 [23]. In this case, there could be a coherence between the phase noise and other sources of frequency noise conversion, which would lead to either constructive or destructive interference depending on the slope of the Ramsey fringe.…”

Performance of an optical single-sideband laser system for atom interferometry

“…Such precision measurements rely on two laser beams having both a stable phase-relation and a controlled frequency difference, for which several compact laser systems have been developed. These laser systems can generally be categorized in either consisting of two lasers that are phase stabilized with respect to each other [2,8,9] or a single laser with a phase modulation to generate multiple frequency components [10][11][12][13][14][15]. The latter requires only a single seed-laser, thus reducing complexity and potentially enabling more compact designs.…”