Self-mixing technique for vibration measurements in a laser diode with multiple modes created by optical feedback

Ruiz-Llata, Marta; Lamela, Horacio

doi:10.1364/ao.48.002915

Cited by 29 publications

(23 citation statements)

References 15 publications

(44 reference statements)

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“…6). This may be due to different gain and phase shifts encountered by individual modes making up the tri-modal signal which are incoherently superimposed [15,16].…”

Section: Experimental Observationsmentioning

confidence: 99%

“…"Previous research [15] measured the optical spectra corresponding to multiple modes undergoing optical feedback. The number of modes undergoing SM was controlled by varying the amount of optical feedback (which in their experimental setup was controlled through a variable optical attenuator).…”

Section: Experimental Observationsmentioning

confidence: 99%

“…However, in case of change in LD modality (e.g. switching from mono-modal to bi-, or even tri-modal emission), different individual modes [14] under SM are incoherently superimposed and a corresponding subperiodicity appears in the SM signal [15,16]. As a result, fringes within the multimodal SM signal need to be interpreted differently.…”

mentioning

confidence: 99%

“…As a result, fringes within the multimodal SM signal need to be interpreted differently. Thus, if the LD under optical feedback exhibits multi-modal behavior during the course of continuous sensing of a remote target then the corresponding multiplicity of SMI fringes needs to be appropriately detected and classified in order to correctly retrieve the target displacement with potentially improved SMI sensor resolution [15,17]. This multiplicity of SMI fringes, however, turns into a source of drastic increase in measurement error [16] in case failure occurs in detecting the change in multiplicity of SMI fringes.…”

mentioning

confidence: 99%

“…Variation can occur in LD modality [14,17] due to change in laser diode' operating current [14] or temperature [15] while change in length of external cavity also influences the modality of the laser under optical feedback [16]. Currently, change in modality cannot be detected without introducing optical components and spectroscopic instruments into the SM sensor set-up [15]. Such introduction of additional optical components, however, compromises the inherent simplicity (see Fig.…”

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confidence: 99%

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Automatic Detection of Multi-Modality in Self-Mixing Interferometer

et al. 2018

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Laser feedback based self-mixing interferometry (SMI) has been demonstrated for diverse metric sensing applications. Typically, SMI sensors are based on such laser diodes (LDs) which provide mono-modal emission resulting in SMI signals in which each interferometric fringe occurs due to change in optical path length of λ/2, where λ is emission wavelength. However, in case multiple laser modes undergo SMI, then each mode contributes its own set of fringes. As LDs can emit multiple modes under variable operating conditions, so, non-detection of multiple SMI modes can cause drastic increase in measurement error due to wrong interpretation of fringes. Previously, detection of multiple laser modes undergoing SMI was achieved by adding spectroscopic instruments to the SMI setup. This, however, compromises the inherent simplicity of SMI sensing. In this work, an automatic SMI based multi-modality detection method is proposed which is able to detect if multiple modes of deployed LD are undergoing SMI and are contributing additional fringes within the SMI signal under variable sensing conditions. Such detection enables correct interpretation of SMI fringe count and can be used to signal occurrence of modehopping or secondary mode excitation. The method uses an artificial neural network, able to automatically identify uni-, bi-, or tri-modal SMI signals. Two different LDs (emitting at 637 nm and 650 nm) were used to acquire 131 experimental uni-, bi-, and tri-modal SMI signals for variable operating conditions and target vibration amplitude. The proposed system has achieved modality detection accuracy of 98.57% on 70 unseen experimental SMI signals.

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“…6). This may be due to different gain and phase shifts encountered by individual modes making up the tri-modal signal which are incoherently superimposed [15,16].…”

Section: Experimental Observationsmentioning

confidence: 99%

Section: Experimental Observationsmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%