Spectroscopy and Coherence of an Excited-State Transition in Tm:YAlO at Telecommunication Wavelength
This paper reports the first demonstration of optical coherence in an excited-state transition of a rare-earth crystal, characterizing the spectroscopic and coherence properties of the 1451.37 nm transition in Tm:YAlO at telecommunication wavelengths and achieving a coherence time of 4.75 s, thereby suggesting its potential for quantum technology applications.