Spectral response of an upconversion detector and spectrometer

Area of Science:

• Optics and Photonics
• Spectroscopy
• Nonlinear Optics

Background:

• Upconversion detection utilizes high-conversion-efficiency, sum-frequency generation (SFG) for infrared spectroscopy.
• The spectral selectivity of upconversion spectrometers is governed by the SFG spectral response function.
• This response function is sensitive to variations in pump power.

Purpose of the Study:

• To theoretically and experimentally investigate the spectral response of an upconversion detector.
• To analyze the impact of pump power on the SFG spectral response function.
• To discuss the implications for using upconversion detectors as infrared spectrometers.

Main Methods:

• Theoretical calculation of the spectral response as a function of pump power.
• Experimental measurement of upconversion spectra using a periodically poled LiNbO₃ waveguide.
• Comparison of theoretical predictions with experimental results.

Main Results:

• The SFG spectral response function varies significantly with pump power.
• Excellent agreement was achieved between theoretical calculations and experimental measurements.
• The spectral response at maximum internal conversion efficiency differs from that at low pump power.

Conclusions:

• Upconversion detectors show promise for infrared spectroscopy.
• Understanding and controlling the pump power dependence of the SFG spectral response is crucial for optimizing performance.
• The findings provide valuable insights for the design and application of upconversion-based spectrometers.