26th Australian Institute of Physics Congress and the Australian and New Zealand Conference on Optics and Photonics

RV Investigator Field Trials of Compact Underwater LiDAR Using Micro-Joule Scale GaN Semiconductor Laser Source.

Not scheduled

20m

Belinda Hutchinson Building (The University of Sydney )

Contributed Oral ANZOS | Photonics and Optics (ANZCOP)

Description

Pulsed gallium nitride (GaN) semiconductor lasers offer a compact, robust, and cost-effective source for underwater LiDAR (Light detection and ranging), with applications in object detection, property measurement, optical sensing, environmental monitoring, and defence [1,2]. Practical deployment, however, requires sufficient pulse energies to overcome absorption and scattering, especially when operating in turbid waters or high background illumination (daytime).

We report a micro-joule-class nanosecond GaN semiconductor laser source, spectrally centred around 460 nm. This wavelength was deliberately selected to minimise optical absorption in clear water and therefore improve underwater depth penetration. The power-scaled source was validated through a sequence of field trials, from a controlled 50 m swimming pool to open-ocean testing aboard CSIRO’s Research Vessel (RV) Investigator. Across these trials, the LiDAR system demonstrated object detection and depth resolved elastic, Raman, and fluorescence backscatter in depths beyond 80 m. The compact semiconductor architecture of this laser source provides a practical advantage over conventional bulky solid-state sources for deployable underwater sensing applications.

These results show that micro-joule scale GaN semiconductor lasers can serve as practical devices for compact underwater optical sensing systems. The demonstrated increase in pulse energy, combined with field validation in realistic marine environments, provides a pathway toward deployable blue-laser platforms for underwater profiling, target detection, and environmental monitoring.

References

[1] Kitzler, O., Li, Z., Taylor, C. J., Dawes, J. M., Pask, H. M., Downes, J. E., & Spence, D. J. ”Ocean LiDAR using gallium nitride laser excitation for determining subsurface water temperature.” In Ocean Sensing and Monitoring XVII (Vol. 13482, p. 52). SPIE (2025).

[2] Kitzler, O., Taylor, C. J., Li, Z., Dawes, J. M., Pask, H. M., Spence, D. J., & Downes, J. E. ”Photon counting marine LiDAR using blue laser diode excitation.” Optics Express, 32(26), 45969-45977 (2024).