Frequency-tunable THz polariton laser based on intracavity RbTiOPO4 crystal

A THz laser source based on stimulated polariton scattering (SPS) in an intracavity RbTiOPO₄ (RTP) crystal is reported, with frequency-tunable output from 3.10 to 3.16 THz and from 3.50 to 4.15 THz. The gap exhibited from 3.17 to 3.49 THz is located in the vicinity of the 104 cm^-1 absorbing mode in RTP. A maximum average output power of 16.2 μW was measured at 3.80 THz.