  With their optical wavelength in the near infrared (790-800nm) and their
unique spectroscopic properties at cryogenic temperatures, thulium-doped
crystals are at the center of many architectures linked to classical signal
processing and quantum information. In this work, we focus on Tm-doped YSO, a
compound that was left aside in the mid-1990s due to its rather short optical
coherence lifetime. By means of time-resolved hole-burning spectroscopy, we
investigate the anisotropic enhanced nuclear Zeeman effect and demonstrate
deep, sub-MHz, persistent spectral hole burning under specific magnetic field
orientation and magnitude. By estimating the experimental parameters
corresponding to a real-scale ultrasound optical tomography setup using Tm:YSO
as a spectral filter, we validate Tm:YSO as a promising compound for medical
imaging in the human body.

Optics;Quantum Physics