The growth and laser amplifier performance of a large-aperture Nd:LuAG ceramic are reported. Using the vacuum sintering and high-temperature insostatic pressing (HIP) methods, three pieces of a 50 mm-aperture Nd:LuAG ceramic are fabricated and used as the gain medium in a diode-pumped nanosecond distributed active mirror amplifier chain (DAMAC). The energy storage capacity of large-aperture Nd:LuAG is investigated and compared with that of Nd:YAG. Energy amplification up to 10.3 J at 10 Hz is achieved, which, to the best of our knowledge, produces the highest peak power (1 GW) using Nd:LuAG. The excellent energy storage and extraction performance confirm the great potential of Nd:LuAG in high-energy scaling.

The operation of a mid-infrared laser at 2244 nm in a Cr:ZnS polycrystalline channel waveguide fabricated using direct femtosecond laser writing with a helical movement technique is demonstrated. A maximum power output of 78 mW and an optical-to-optical slope efficiency of 8.6% are achieved. The compact waveguide structure with 2 mm length was obtained through direct femtosecond laser writing, which was moved on a helical trajectory along the laser medium axis and parallel to the writing direction.

Radiation dosimetry plays a crucial role in the Quality Assurance (QA) in radiotherapy. To date this is limited to monitoring the overall dose over the complete beam time and so there is limited information on the actual beam quality. An optical fibre sensor is developed based on cerium doped yttrium aluminum garnet (YAG:Ce) scintillator. The temporal resolution and stability of this scintillator-based optical fibre sensor have been experimentally evaluated and directly compared with similarly fabricated sensors based on Terbium activated Gadolinium Oxysulfide (GOS:Tb) and commercial plastic scintillating fibre, BCF-12. The photon yield and repeatability of the YAG based sensor is compared in the clinical setting with the BCF-12 sensor, and both show a high stability. The coefficient of variation of the YAG sensor is 0.7 %, which is lower than the BCF sensor with a coefficient of variation of 1.4 %.