Fast Computational Phase and Timing Correction for Multiheterodyne Spectroscopy

(Princeton Docket # 17-3351)

Inventors: Gerard Wysocki, Jonas Westberg, Lukasz Sterczewski

Digital phase and timing correction techniques address critical challenges in multiheterodyne and dual-comb spectroscopy by compensating for laser instabilities, enabling high-resolution measurements with cost-effective semiconductor lasers. These methods improve signal quality while reducing system complexity, making portable and real-time spectroscopic systems more feasible.

Technical Approach

The core innovation involves dual-stage correction of timing and phase distortions through computational methods:

1. Repetition Rate Fluctuation Correction:
   • Dominant RF beat notes are filtered and mixed to generate an instantaneous phase signal.
   • Interferograms are resampled on a non-uniform time grid derived from detected repetition rate variations, aligning comb teeth and reducing timing jitter.
2. Offset Frequency Noise Mitigation:
   • High signal-to-noise ratio (SNR) beat notes track common-mode frequency fluctuations.
   • A multiplicative, linearly varying phase correction is applied to suppress residual noise, sharpening spectral lines.

This approach eliminates the need for external reference lasers or high-bandwidth feedback loops, relying instead on real-time digital signal processing (e.g., FPGA platforms) to achieve sub-kHz beat note linewidths

APPLICATIONS

ADVANTAGES

• Environmental Monitoring: Detection of trace gases with high resolution in real time.
• Industrial Process Control: Rapid chemical analysis in manufacturing.
• Medical Diagnostics: Breath analysis for disease biomarkers using compact spectrometers.
• Fundamental Research: Time-resolved studies of ultrafast processes (e.g., combustion, plasma dynamics)

• Cost Reduction: Enables use of free-running semiconductor lasers (e.g., quantum cascade lasers) instead of stabilized frequency combs368.
• Improved SNR: Narrowed beat note bandwidths (from MHz to kHz) and suppressed noise pedestals enhance sensitivity.
• Scalability: Compatible with diverse RF configurations, including systems with overlapping or non-overlapping beat notes.
• Portability: Simplified hardware (no moving parts or complex stabilization setups) supports field-deployable systems

Stage of Development

Prototype – experimentally tested

Contact
Renee Sanchez

New Ventures & Licensing Associate • (609) 258-6762 • renee.sanchez@Princeton.edu