Laser design makes major breakthrough in gaseous stimulated Raman scattering
DOI: 10.1063/10.0043213
Laser design makes major breakthrough in gaseous stimulated Raman scattering lead image
By leveraging the interaction between high-intensity lasers and gaseous media such as hydrogen and deuterium, stimulated Raman scattering can induce laser frequency shifts through molecular vibration or rotation, thus filling wavelength gaps commercial lasers cannot reach. Gases allow for a high-damage threshold, large frequency shifts, and excellent optical uniformity, making them ideally suited for generating high-power lasers that reach the ultraviolet and infrared spectral range.
But despite efforts to reconcile it, a longstanding tradeoff dilemma plagues the nonlinear optical technology. High output energy results in poor beam quality, while high beam quality results in compromised energy and repetition rate.
Sun et al. designed a near-infrared gaseous Raman laser that integrates three distinct strategic advantages: sub-atmospheric pressure, cylindrical lens focusing, and a multi-pass cell structure.
“Low gas pressure is akin to emptying an overcrowded subway car,” said author Jingwei Guo. “It creates enough space between passengers so that no matter how hard we push them with high laser energy, we won’t trigger a chaotic ‘stampede.’”
The cylindrical lens focuses light in a long line, where force can safely spread and allow for more power to be introduced, as opposed to traditional lasers that focus energy on a tiny dot.
The multi-pass cell structure was designed so that, instead of crossing the Raman medium once, the light weaves back and forth, allowing the beam to continuously accumulate energy and produce ultra-high energy output.
“Our experimental design enables a substantial boost in laser energy and repetition rate … without compromising beam quality,” said Guo. “In practice, it can be adjusted for different scenarios: It is compatible with high-power lab systems and can also be integrated into compact, portable laser devices.”
Source: “Cylindrical-lens-focusing multipass configuration in sub-atmospheric pressure: Breaking the energy-beam quality trade-off in stimulated hydrogen Raman laser,” by Jinglu Sun, Suya Song, Tao Lin, Xianglong Cai, Yannan Tan, Ming Xu, and Jingwei Guo, Harmonics and Scattering (2026). The article can be accessed at https://doi.org/10.1063/5.0319797 .
