Wavelength-tunable femtosecond pulsed laser for the characterisation of solid-state sensors

Abstract The Two-Photon Absorption (TPA) process provides an excellent method for the characterisation of solid-state sensors due to its intrinsic 3D resolution for the excitation of electron-hole pairs. This paper presents the commissioning of a system composed of a Light Conversion PHAROS laser read out with an ORPHEUS optical parametric amplifier with tuneable output wavelength across 310–16000 nm. This is one of the few facilities suitable for particle physics detector applications with a very wide wavelength range and ultra short pulses. The voxel characterisation shows a Rayleigh length of 12.20 ± 0.47 μm and the beam radius at the waist of 1.53 ± 0.04 μm. Initial measurements with silicon and diamond samples are described. The apparatus is characterised with both devices, demonstrating the expected quadratic dependency with the energy per pulse, and different models are presented to explain the signal generated due to reflection. The signal generated in the silicon diode is in good agreement with one dimension voxel model predictions.