Asymmetric laser sideband generation with a tapered semiconductor amplifier

D. Voigt, E.C. Schilder, R. J. C. Spreeuw +1 more

Wayne F. Sharfin, M. Dagenais

Hang Zhou, Qin Luo, Xiao-Bing Deng +4 more

Stimulated Raman transitions are often used in an atom interferometer (AI) for wave packet manipulation. Normally, two lasers with different frequencies contained in a Raman beam are combined first and then amplified by a single tapered amplifier (TA). This configuration can simplify the laser system of the AI, however, additional sidebands will be generated by the TA because of the nonlinear effect in the TA. In this work, the impact of additional sidebands generated with a single TA on the AI is studied. We first observe the additional sidebands in a Raman laser by a Fabry-Pérot interferometer (FPI), and the additional sidebands will be greatly suppressed by reducing the injection laser power of the TA. This is also confirmed by observing the position-dependent Raman transitions induced by additional sidebands at different injection power in an AI. However, the phase shifts induced by additional sidebands are not reduced obviously when the injection power of the TA is reduced. Therefore, it is necessary to separately amplify two lasers contained in the Raman laser by two TAs for a high precision AI. The spectroscopy of Raman laser generated by two TAs is also measured by the FPI, and the impact of additional sidebands on the AI is eliminated. This work has guiding significance for the design of the laser system in a high-precision AI.

Zhixin Meng, Yuhang Li, Yanying Feng

Simultaneous two-frequency amplification is highly desirable in cold atom experiments. The nonlinear response would appear in the two-frequency amplification with a semiconductor tapered amplifier (TA) and has a direct influence on the experimental result. We investigated in detail the effects of frequency difference, total power, and power ratio of two seeding lasers on the output components based on a simplified theoretical model. The simulation results showed that the multiple sideband generation in the amplifier due to self-phase and amplitude modulation could be suppressed and the TA tended to linearly amplify the power ratio between two-frequency components, when the two seeding lasers had a large frequency difference. This was verified experimentally in the output power ratio measurement via a calibrated Fabry–Perot interferometer method with a good linearity and an uncertainty of 1%. We also discussed the consequences of power ratio responses in the amplification in light of cold atom experiments, especially in the ac Stark shift related phase error of Raman-type atom interferometers (AIs). It was shown that the fluctuation of intensity ratio of Raman beams may induce significant systematic errors for an AI gyroscope.

M.J. Adams, H.J. Westlake, M.J. O’Mahony

Jake Zappala, K. Bailey, Zheng‐Tian Lu +2 more

Two methods using a laser-diode tapered amplifier to produce high-power, high-efficiency optical frequency sidebands over a wide tunable frequency range are studied and compared. For a total output of 500 mW at 811 nm, 20% of the power can be placed in each of the first-order sidebands. Functionality and characterization are presented within the sideband frequency region of 0.8-2.3 GHz, and it is shown that both methods can be applied beyond this frequency range. These methods provide a versatile and effective tool for atomic physics experiments.