Optimum local oscillator levels for coherent detection using photoconductors.

Area of Science:

• Optoelectronics
• Photoconductor physics
• Signal processing

Background:

• Photoconductors are key optical detectors.
• Optical local oscillators can influence photoconductor properties.
• Understanding these interactions is crucial for detector performance.

Purpose of the Study:

• To analyze the effects of optical local oscillator power on photoconductor conductance.
• To derive signal-to-noise ratio (SNR) formulations for voltage and current bias.
• To determine optimal operating conditions for photoconductor detectors.

Main Methods:

• Theoretical analysis of photoconductor conductance modulation.
• Derivation of SNR equations for constant voltage and current bias.
• Modeling of photoconductor response under varying optical power.

Main Results:

• Optical local oscillator power significantly affects effective responsivity and signal processing interaction.
• SNR peaks at an optimal local oscillator power for voltage bias.
• Current bias shows a saturation-like effect in the linear region and a true maximum in the quadratic region.

Conclusions:

• The interplay between optical local oscillators and photoconductors is complex.
• Optimizing local oscillator power is critical for maximizing SNR in voltage-biased photoconductors.
• Photoconductor operating region (linear vs. quadratic) dictates SNR behavior under current bias.