An optomechanical device for modulating an optical signal for reducing thermal noise and tracking mechanical resonance of a proof mass assembly (16, 616) comprising a proof mass suspended by a mechanical structure, the mechanical structure having a mechanical resonance frequency and configured such that an optical signal induces a mechanical vibration in the mechanical structure, the optomechanical device comprising a circuit (14,30) configured to: receive, from a light-emitting device, an optical signal; modulate, by a modulator (22A, 22B), the optical signal to remove thermal noise and to drive a mechanical response frequency to the mechanical resonance of the proof mass assembly (16, 616) using a cooling feedback signal and a mechanical resonance feedback signal by: generating, using the modulated optical signal that has passed through the mechanical structure and arrived at a photoreceiver (24A, 24B, 623, 624, 625, 627), the cooling feedback signal to correspond to a thermal noise signal of the modulated optical signal with a total loop gain of zero dB, the loop comprising the mechanical structure, the photoreceiver, and the modulator (22A, 22B), and a phase difference of 180 degrees with noise fluctuations; and generating, using the modulated optical signal that has passed through the mechanical structure, the mechanical resonance feedback signal to drive the mechanical response frequency of the modulated optical signal to the mechanical resonance. receive, from a light-emitting device, an optical signal; modulate, by a modulator (22A, 22B), the optical signal to remove thermal noise and to drive a mechanical response frequency to the mechanical resonance of the proof mass assembly (16, 616) using a cooling feedback signal and a mechanical resonance feedback signal by: generating, using the modulated optical signal that has passed through the mechanical structure and arrived at a photoreceiver (24A, 24B, 623, 624, 625, 627), the cooling feedback signal to correspond to a thermal noise signal of the modulated optical signal with a total loop gain of zero dB, the loop comprising the mechanical structure, the photoreceiver, and the modulator (22A, 22B), and a phase difference of 180 degrees with noise fluctuations; and generating, using the modulated optical signal that has passed through the mechanical structure, the mechanical resonance feedback signal to drive the mechanical response frequency of the modulated optical signal to the mechanical resonance. generating, using the modulated optical signal that has passed through the mechanical structure and arrived at a photoreceiver (24A, 24B, 623, 624, 625, 627), the cooling feedback signal to correspond to a thermal noise signal of the modulated optical signal with a total loop gain of zero dB, the loop comprising the mechanical structure, the photoreceiver, and the modulator (22A, 22B), and a phase difference of 180 degrees with noise fluctuations; and generating, using the modulated optical signal that has passed through the mechanical structure, the mechanical resonance feedback signal to drive the mechanical response frequency of the modulated optical signal to the mechanical resonance.