Beating beats mixing in heterodyne detection schemes

Area of Science:

• Physics
• Signal Processing
• Nonlinear Optics

Background:

• Heterodyne detection is standard for high-frequency signals.
• Conventional understanding attributes signal generation solely to mixing, neglecting beating.
• Beating is considered a linear effect incapable of producing heterodyne signals.

Purpose of the Study:

• To challenge the conventional understanding of heterodyne signal generation.
• To develop a general analytical theory for heterodyne signal formation.
• To investigate the roles of both beating and mixing in heterodyne detection.

Main Methods:

• Derivation of a general analytical theory for heterodyne signal generation.
• Analysis of the influence of mixer nonlinearity on signal generation.
• Numerical simulations to validate theoretical findings.
• Experimental verification using heterodyne force microscopy.

Main Results:

• Both beating and mixing are essential for heterodyne signal generation.
• Beating dominates the heterodyne signal when the mixer's nonlinearity exceeds quadratic order.
• Mixer characteristics dictate sensitivity to beating.
• Experimental and simulation results confirm the theoretical model.

Conclusions:

• The established view of heterodyne signal generation is incomplete.
• Beating plays a critical, often dominant, role in heterodyne signal formation.
• Previous heterodyne measurement results may require re-evaluation due to the significance of beating.