Feedback Regimes of LFI Sensors: Experimental Investigations

Abstract

In this article, we revisit the concept of optical feedback regimes in diode lasers and explore each regime experimentally from a somewhat unconventional point of view by relating the feedback regimes to the laser bias current and its optical feedback level. The results enable setting the operating conditions of the diode laser in different applications requiring operation in different feedback regimes. We experimentally explored and theoretically supported this relationship from the standard Lang and Kobayashi rate equation model for a laser diode under optical feedback. All five regimes were explored for two major types of laser diodes: inplane lasers and vertical-cavity surface emitting lasers. For both lasers, we mapped the self-mixing strength vs. drive current and feedback level, observed the differences in the shape of the self-mixing fringes between the two laser architectures and a general simulation, and monitored other parameters of the lasers with changing optical feedback.

Variability in plant cell water dynamics as a genetic discriminatory method using terahertz quantum cascade laser-based laser feedback interferometry

“…33 This is a highly compact system where the emitter also acts as the detector for the THz radiation. [34][35][36] THz is generated by an encased QCL chip, where a Stirling cooler maintains the operating temperature at 50K. The beam passes through a 30 mm collimating lens (Tsurupica, BBlaser Inc.); and is reflected through a set of 75 mm static reflecting mirrors, a 50 mm rasterising focusing mirror (Optics in Motion) and through a 50 mm focusing lens (Tsurupica, BBlaser Inc.) onto the sample before being reflected back to the QCL (Fig.…”

Laser Optical Feedback Turns 60

“…Their study is a milestone with almost one thousand citations and set the framework for later development, notably by Donati and Horng [ 10 ] and Jumpertz et al [ 11 ]. The article published in this Special Issue by Bertling and co-workers [ 12 ] adds a new dimension to the diagram of the self-mixing regimes, typically framed by the target distance and the feedback strength axis. They studied the role of the laser bias current in setting the switching point between different operational regimes in two types of semiconductor diode lasers, which are mostly used in LSM applications: vertical cavity surface emitting lasers (VCSELs) and distributed feedback Bragg (DFB) lasers.…”

Laser Self-Mixing Interference: Optical Fiber Coil Sensors for Acoustic Emission Detection

“…In SMI sensing schemes, optical feedback coefficient C affects the waveform of an SMI signal and the stability of an SMI system [31,32]. Figure 2 shows the simulated SMI signals with different optical feedback coefficients.…”