Frequency-swept feedback interferometry for noncooperative-target ranging with a stand-off distance of several hundred meters

Abstract

Frequency-swept interferometry (FSI) is a powerful ranging method with high precision and immunity to ambient light. However, the stand-off distance of the current FSI-based ranging system for noncooperative targets is relatively short because the weak echo power cannot provide the needed signal-to-noise ratio (SNR). Here, we report a ranging method that combines FSI and the laser feedback technique. Compared with conventional FSI, the interference between the weak echo signal and the local oscillator occurs in the laser cavity, which enhances the signal spontaneously and then provides an improved SNR. In the experiments, the detection limit of the echo power is less than 0.1 fW, with a 1 mW probe beam. Based on the enhancement from the laser feedback technique, the system can detect a noncooperative target that is up to hundreds of meters away in space without extra optical amplifiers. On the other hand, a large stand-off distance makes the system sensitive to environmental disturbance, which degrades the ranging precision. To address this issue, an interferometry-based compensation device, which is also sensitive to weak echoes from noncooperative targets, is proposed to monitor the optical-path-length drifts and ensure accurate beat frequency recognition. Moreover, the device can record distance changes during the integration time of ranging and track a moving target precisely with improved temporal resolution. Owing to the high sensitivity and the validity of the compensation approach, the standard deviation in 10 measurements is better than 0.07 mm when targeting an aluminum sheet at approximately 152 m. Generally, with a large range, high relative precision, and low photon consumption, the novel technical scheme for laser ranging demonstrates new capabilities that promise to enable a wide range of applications, such as large equipment assembly and noncooperative-target tracking.

An Ultrasensitive and Universal Surface Plasmonic Biosensor for Detection of Micropollutants in Aquatic Environments

“…10,11 In this scheme, the laser source acts as an emitter, responder, and intrinsic amplifier simultaneously, which does rarely need optical alignment and reduces optical components required. Because of its compactness, self-collimation, and sensitivity, LHFI has been widely explored for displacement sensing, 12 particle detection, 13 confocal tomography, 14 and so on. Despite its promise, enhanced sensitivity to SPR via the LHFI is rarely reported so far.…”

“…More specifically, the frequency-shifted incident light senses and then partially returns to the laser cavity, in turn resonating with the relaxation oscillation and inducing the intensity modulation of the laser; as a consequence, the modulated output of the laser can be enhanced even up to 10 6 -fold compared with the feedback one. , In this scheme, the laser source acts as an emitter, responder, and intrinsic amplifier simultaneously, which does rarely need optical alignment and reduces optical components required. Because of its compactness, self-collimation, and sensitivity, LHFI has been widely explored for displacement sensing, particle detection, confocal tomography, and so on. Despite its promise, enhanced sensitivity to SPR via the LHFI is rarely reported so far.…”

Ultrasensitive Screening of Endocrine-Disrupting Chemicals Using a Surface Plasmon Resonance Biosensor with Polarization-Compensated Laser Heterodyne Feedback

“…8,9 In this scheme, the laser source acts as an emitter, responder, and intrinsic amplifier simultaneously, which does rarely need optical alignment and reduces the required optical components. Because of its compactness, self-collimation, and sensitivity, LHFI has been widely explored for displacement sensing, 10 particle detection, 11 confocal tomography, 12 and so on. Despite its promise, enhanced sensitivity to SPR via LHFI is rarely reported so far.…”

“…More specifically, the frequency-shifted incident light senses and then partially returns to the laser cavity, in turn resonating with the relaxation oscillation and inducing the intensity modulation of the laser; as a consequence, the modulated output of the laser can be enhanced even up to 10 6 -fold compared with the feedback one. , In this scheme, the laser source acts as an emitter, responder, and intrinsic amplifier simultaneously, which does rarely need optical alignment and reduces the required optical components. Because of its compactness, self-collimation, and sensitivity, LHFI has been widely explored for displacement sensing, particle detection, confocal tomography, and so on. Despite its promise, enhanced sensitivity to SPR via LHFI is rarely reported so far.…”

Microwave photonic approach to spatial distance measurement

“…However, there is still significant room for improvement in terms of miniaturization, low cost, high accuracy and so on. A high-performance optical range finder will have wild application prospects [9][10] .…”