Self-mixing interference effects in tunable diode laser absorption spectroscopy

Abstract

We report the effects of self-mixing interference on gas detection using tunable diode laser spectroscopy. For very weak feedback, the laser diode output intensity gains a sinusoidal modulation analogous to that caused by low finesse etalons in the optical path. Our experiments show that self-mixing interference can arise from both specular reflections (eg cell windows) and diffuse reflections (eg Spectralon TM and retroreflective tape), potentially in a wider range of circumstances than etalon-induced interference. The form and magnitude of the modulation is shown to agree with theory. We have quantified the effect of these spurious signals on methane detection using wavelength modulation spectroscopy, and discuss the implications for real gas detectors.

Analysis of Random Noise and Long-Term Drift for Tunable Diode Laser Absorption Spectroscopy System at Atmospheric Pressure

“…In [22], D. Masiyano et al introduced self-mixing induced signal drift. For different types of lasers such as the Fabry-Perot laser, the DFB laser and vertical-cavity surface emitting laser (VCSEL), self-mixing interference can be caused by returned light from a flat mirror or a rough surface.…”

“…Many factors including the wavelength drift, the etalon fringe drift, and the change of self-mixing interference in the laser [22] can produce signal drift.…”

Designing a reliable leak bio-detection system for natural gas pipelines

“…The tunable diode laser spectroscopy system (alternative A4) offers substantial benefits on production scale that, in the near future, are expected to generate a lowered energy consumption device and less maintenance of equipment [75]. The cost of these systems, however, is still relatively high and their application is usually limited to situations where an integrated measurement of methane gas density over relatively long open path lengths is required [122]; consequently, the system is typically used to measure the presence of clouds of gas within lengths of the order of meters. According to the experts opinion, photoacoustic technology (alternatives A5 and A6) offers a realistic potential to the development of field sensors based on compactness of the systems, the ease of use, their ability to operate at atmospheric pressure and their insensitivity to optical misalignment.…”

Applied optics to engineering photonics: a retrospective

“…We are investigating non-dispersive infrared (NDIR) techniques for the measurement of CO 2 [59] and formaldehyde and high resolution spectroscopy based on tuneable diode laser absorption spectroscopy (TDLAS) techniques to detect a range of gases including methane [60][61][62][63][64]. A thrust of this research has been to improve the sensitivity by reducing the interference effects that occur from using narrow linewidth lasers.…”