Model of multiple mode gain competition in self-mixing laser diode

Denoising of Laser Self-Mixing Interference by Improved Wavelet Threshold for High Performance of Displacement Reconstruction

“…The SMI signal is converted and amplified by the current-voltage circuit, and the data acquisition card (NIUSB-6341) is used for data acquisition, and the SMI signal waveform is displayed on the computer in real time. The details of the experimental setup are given in reference [6]. In this experiment, the external cavity length is 33.9 mm, the modulation frequency is 10 Hz, and the modulation amplitude is 2 V. The power of the diode laser in operation is about 3 mW.…”

“…In recent years, the application of laser self-mixing interferometry in micro-displacement measurement has gained significant attention [1][2][3][4][5]. Laser self-mixing interferometry offers several advantages over traditional micro-displacement measurement techniques, including no optical interferometer external to the source, no external photodetector, noncontact operation, high sensitivity, high precision, environmental insensitivity, and high resolution [6][7][8][9][10][11]. As a result, laser self-mixing interferometry has emerged as a prominent research area in micro-displacement measurement [8][9][10].…”

“…Hence, the lasing field amplitude and frequency are modulated by the term ϕ(t) = 2ks(t) [11]. Power fluctuations ∆P in the steady-state operation of the LD in the weak feedback regime follow the equation: ∆P~cos(ϕ(t)) [6]. In practical measurement scenarios, the presence of various sources of noise, such as ambient temperature, fluctuation in the LD driving source and other disturbances, can be introduced into self-mixing interference (SMI) signals [12,13].…”