Daniel Suwignjo
Research Mentor: Zheshen Zhang
Mentor Department: Electrical and Computer Engineering, Engineering
Author(s): Daniel Suwignjo, William Ward, Zheshen Zhang
Session: Session 6 (3:00 PM – 3:50 PM)
Presentation Type: Poster 56
Abstract
Quantum experiments involving lasers rely heavily on the stability of the laser. Because atomic particles’ energy transition levels are incredibly narrow, a slight instability in laser frequency can cause the experiment to fail completely. This project aims to utilize the Pound-Drever-Hall (PDH) locking method to create near-zero error lasers suitable for quantum experiments. The initial laser is first modulated by an RF signal from a Pockels Cell driven by a Local Oscillator. This generates sidebands that get reflected by the optical cavity along with some leakage from the phase-shifted laser. The cavity’s reflections are then captured by a photodetector and turned into an electrical signal. By demodulating the photodetector’s signal, it is possible to isolate the phase shift as a DC signal using a mixer and a low-pass filter. The phase shift is measured because at low error, the phase shift can be approximated as the derivative of the cavity’s reflection with respect to frequency. The DC signal is then processed through a PID controller that actively corrects the laser to its intended state, thus completing a feedback loop.
