External digital power stabilization system for levitated optomechanics sensor

Levitated microspheres have enabled a wide variety of precision sensing applications which have caught great attentions in recent years. Optical tweezers technology is one of the most important methods of microspheres levitation. The stability of laser power directly affects the microspheres levitation and the precision of the measurement. This paper discusses the major factors of power stabilization in semiconductor laser. A PID-controlled model is used to control the feedback on the laser. The system mode is established after the analyzing of the characteristic of the model parameters. The experiment is demonstrated with a commercial semiconductor laser. With the external power stabilization module a 16dB laser power stability control is achieved at the relaxation oscillation, and the long-term stability is improved from 3% to 0.4%.