TY - JOUR
T1 - Active Cancellation of Servo-Induced Noise on Stabilized Lasers via Feedforward
AU - Li, Lintao
AU - Huie, William
AU - Chen, Neville
AU - Demarco, Brian
AU - Covey, Jacob P.
N1 - Publisher Copyright:
© 2022 American Physical Society.
PY - 2022/12
Y1 - 2022/12
N2 - Many precision laser applications require active frequency stabilization. However, such stabilization loops operate by pushing noise to frequencies outside their bandwidth, leading to large "servo bumps"that can have deleterious effects for certain applications. The prevailing approach to filtering this noise is to pass the laser through a high-finesse optical cavity, which places constraints on the system design. Here, we propose and demonstrate a different approach where a frequency error signal is derived from a beat note between the laser and the light that passes through the reference cavity. The phase noise derived from this beat note is fed forward to an electro-optic modulator after the laser, carefully accounting for relative delay, for real-time frequency correction. With a hertz-line-width laser, we show 20dB noise suppression at the peak of the servo bump (approximately 250kHz) and a noise-suppression bandwidth of approximately 5MHz - well beyond the servo bump. By simulating the Rabi dynamics of a two-level atom with our measured data, we demonstrate substantial improvements to the pulse fidelity over a wide range of Rabi frequencies. Our approach offers a simple and versatile method for obtaining a clean spectrum of a narrow-line-width laser, as required in many emerging applications of cold atoms, and is readily compatible with commercial systems that may even include wavelength conversion.
AB - Many precision laser applications require active frequency stabilization. However, such stabilization loops operate by pushing noise to frequencies outside their bandwidth, leading to large "servo bumps"that can have deleterious effects for certain applications. The prevailing approach to filtering this noise is to pass the laser through a high-finesse optical cavity, which places constraints on the system design. Here, we propose and demonstrate a different approach where a frequency error signal is derived from a beat note between the laser and the light that passes through the reference cavity. The phase noise derived from this beat note is fed forward to an electro-optic modulator after the laser, carefully accounting for relative delay, for real-time frequency correction. With a hertz-line-width laser, we show 20dB noise suppression at the peak of the servo bump (approximately 250kHz) and a noise-suppression bandwidth of approximately 5MHz - well beyond the servo bump. By simulating the Rabi dynamics of a two-level atom with our measured data, we demonstrate substantial improvements to the pulse fidelity over a wide range of Rabi frequencies. Our approach offers a simple and versatile method for obtaining a clean spectrum of a narrow-line-width laser, as required in many emerging applications of cold atoms, and is readily compatible with commercial systems that may even include wavelength conversion.
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U2 - 10.1103/PhysRevApplied.18.064005
DO - 10.1103/PhysRevApplied.18.064005
M3 - Article
AN - SCOPUS:85143727607
SN - 2331-7019
VL - 18
JO - Physical Review Applied
JF - Physical Review Applied
IS - 6
M1 - 064005
ER -