Laser-Induced Interference to Infrared Detector Using Continuous Wave and Short-Pulse Lasers.

Area of Science:

• Optoelectronics
• Laser-Material Interactions
• Infrared Detection Technology

Background:

• Lead sulfide (PbS) infrared detectors are crucial for various applications.
• Understanding laser-induced interference is vital for reliable detector operation.
• Previous studies have not fully characterized the distinct interference mechanisms of pulsed vs. CW lasers on PbS detectors.

Purpose of the Study:

• To investigate and differentiate the laser-induced interference effects of nanosecond pulsed and continuous wave (CW) lasers on a PbS infrared detector.
• To analyze the characteristics of transient and continuous interference signals.
• To determine the interference threshold for PbS detectors under laser irradiation.

Main Methods:

• Constructed a laser interference experiment system to measure time-varying response signals.
• Utilized a 1064 nm nanosecond pulsed laser and a 10 Hz CW laser with millimeter-scale spot diameter.
• Analyzed transient interference from pulsed lasers and combined interference from both laser types.
• Employed a probit model to establish the interference threshold.

Main Results:

• Pulsed lasers induced only transient interference, with amplitude linearly proportional to laser fluence.
• CW lasers caused significant, continuous amplitude reduction of the detector's response signal.
• CW laser interference became dominant at power densities ≥ 4.1 W/cm².
• Temporary detector blindness occurred at CW laser fluence of 6.1 W/cm².

Conclusions:

• Pulsed and CW lasers exhibit distinct interference mechanisms on PbS infrared detectors.
• CW laser interference poses a significant threat, potentially causing temporary detector blindness.
• Interference thresholds can be determined using a probit model, crucial for operational safety and reliability.