# Fast interrogation wavelength tuning for all-optical photoacoustic imaging

**Authors:** Jérémy Saucourt, Antonin Moreau, Julien Lumeau, Hervé Rigneault, Thomas Chaigne  
**arXiv:** [2210.08592](https://arxiv.org/abs/2210.08592)  
**Date:** 2022-10-16  
**Summary page:** https://www.summarizepaper.com/en/paper/2210.08592v1/

## Key points

- Novel approach to photoacoustic imaging using fast interrogation wavelength tuning for all-optical detection of ultrasound
- Photoacoustic imaging provides high sensitivity and large bandwidth at high acoustic frequencies, allowing for higher spatial resolutions compared to conventional piezoelectric detection
- Broadband source and a fast tunable acousto-optic filter used to adjust the interrogation wavelength at each pixel within a few microseconds
- Linearly-polarized broadband amplified spontaneous emission (ASE) source with a -3dB bandwidth of 10 nm centered around 1027 nm used
- Acousto-optic tunable filter (AOTF) driven by a waveform generator allows for switching between two different RF frequencies and thus two different diffracted optical wavelengths in just 1 microsecond
- Validity of this approach demonstrated by performing photoacoustic imaging with a highly inhomogeneous Fabry-Pérot sensor
- Results show that this method provides high-resolution images with improved contrast and signal-to-noise ratio compared to traditional methods
- Offers significant advantages over traditional methods, such as faster acquisition times and improved image quality
- Potential applications in various fields including medical imaging, non-destructive testing, and material characterization.

## Summary

This paper presents a novel approach to photoacoustic imaging using fast interrogation wavelength tuning for all-optical detection of ultrasound. Photoacoustic imaging provides high sensitivity and large bandwidth at high acoustic frequencies, allowing for higher spatial resolutions compared to conventional piezoelectric detection. The proposed method uses a broadband source and a fast tunable acousto-optic filter to adjust the interrogation wavelength at each pixel within a few microseconds. The system uses a linearly-polarized broadband amplified spontaneous emission (ASE) source with a -3dB bandwidth of 10 nm centered around 1027 nm. The beam is spectrally filtered by an acousto-optic tunable filter (AOTF) driven by a waveform generator, allowing for switching between two different RF frequencies and thus two different diffracted optical wavelengths in just 1 microsecond. The authors demonstrate the validity of this approach by performing photoacoustic imaging with a highly inhomogeneous Fabry-Pérot sensor. The results show that this method provides high-resolution images with improved contrast and signal-to-noise ratio compared to traditional methods. Overall, this new approach offers significant advantages over traditional methods, such as faster acquisition times and improved image quality. It has potential applications in various fields including medical imaging, non-destructive testing, and material characterization.