In-Depth Study of the Output Current Induced by a Millisecond Laser Pulse in a Silicon-Based Biased Quadrant Photodetect
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Journal of Russian Laser Research, Volume 41, Number 5, September, 2020
IN-DEPTH STUDY OF THE OUTPUT CURRENT INDUCED BY A MILLISECOND LASER PULSE IN A SILICON-BASED BIASED QUADRANT PHOTODETECTOR Hongxu Liu, Di Wang, Chenang Li, and Guangyong Jin∗ The Key Laboratory of Jilin Province Solid-State Laser Technology and Application Changchun University of Science and Technology Jilin Province 130022, People’s Republic of China ∗ Corresponding
author e-mail:
jgycust @ 163.com
Abstract In this study, we measure the output current of a silicon-based positive-intrinsic-negative (p-i-n) quadrant photodetector (QPD) exposed to a millisecond-pulse laser radiation. We study the output current curve for a cell at different laser energy fluences and pulse widths. The results obtained show that the behavior of the output current involves a holding current stage as the photo-generated current stage declines with time. Based on these results and the p-i-n structure, we analyze such a behavior.
Keywords: quadrant photodetector, millisecond pulse laser, laser irradiation, output current.
1.
Introduction
A QPD is one of the most commonly-used position-sensitive laser devices due to its low noise, fast response, high sensitivity, ease of optical alignment, wide operating temperature range, and simple signal circuitry [1]. However, since the QPD is positioned in the focal plane of the optical system, it is prone to laser damage [2–5]. As a consequence, it is important to study the effect of laser irradiation on the device performance and its parameters. In the past few years, many scholars have carried out significant research on the interaction between lasers and photodetectors. They focused on the off-line experimental results, such as morphology damage, response level, and dark current, as well as the on-line experimental results such as the surface temperature rise [6–8]. Indeed, the principle of QPD positioning consists in comparing the output currents from each of the four cells of the QPD to determine the position of the spot. Therefore, the study of the output current is very important [9]. We investigate the output current induced in a biased QPD by a millisecond-pulse laser radiation. The output current is obtained under 1064 nm millisecond laser pulses. In addition, the output current curves are measured for different energy fluences and pulse widths. The results provide information on the laser damage and help in determining the ways of protecting the p-i-n diode.
2.
Experimental Setup
The on-line monitoring system is shown in Fig. 1 [7]. A Nd:YAG laser (1064 nm) with a 10 J maximum output and a pulse width in the range of 0.5 – 3.0 ms is used. In the experiment, the laser radiation is Manuscript submitted by the authors in English on July 29, 2020. c 2020 Springer Science+Business Media, LLC 1071-2836/20/4105-0528 528
Volume 41, Number 5, September, 2020
Journal of Russian Laser Research
focused on the surface of the sample by a lens with a focal length of 150 mm. The laser spot radius is 500 μm. The energy meter ta
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