21 W, 18 ps, passively mode-locked Nd:YAG oscillator with a single side-pumped laser head

Compact X-rays sources raise a great enthusiasm in life sciences for applications such as protein crystallography, medical imaging or radiotherapy. Such X-rays can be produced by Thomson scattering of photons coming from a laser source colliding with electrons. However, Thomson scattering is very inefficient. Real-world life science on-site applications requiring high X-rays flux, a scheme based on a mode-locked picosecond laser injected in a Fabry-Perot cavity combined with an electron storage ring has been explored [1]. This technology can be pushed-up with a powerful high repetition-rate mode-locked laser injected in a high finesse cavity enabling to reach the intracavity average power up to few hundreds of kW required by the medical applications. The design of the laser system can then be based either on a low power oscillator combined with a relatively sophisticated high gain amplifier, or on a powerful oscillator seeding a low gain amplifier. However, a powerful single oscillator delivering a few tens of Watts average power with 15–20 ps pulses coupled with a 1000 gain Fabry-Perot cavity would be sufficient as a demonstrator for imaging application. Therefore, in this contribution, we propose a design for a 20W-sub-20 ps class mode-locked Nd:YAG oscillator.