Quantum interference of three LO modes in p-type Ga0.5In0.5P: Contribution of a trigonal phonon mode

Electro-magnetic Induced Transparency (EIT) has been studied as a mechanism of lasers without population inversion. Little attention has been given to EIT on phonon systems, while it has a potential of application to EIT and thus THz laser and modulator. Quantum interference of multiple longitudinal optical (LO) phonon modes and the continuum of inter-valence band transition is studied in this report. p-type Ga
_0.5
In
_0.5
P alloy system is studied by Raman spectroscopy. The detailed analysis by spectrum fitting reveals the superposition of characteristic asymmetric profile and the contribution of a trigonal phonon mode due to ordering effect of Ga
_0.5
In
_0.5
P. These results indicate that Ga
_0.5
In
_0.5
P is a possible material of EIT on phonon systems. It is expected that the change of the degree of ordering leads to the control of quantum interference for application of EIT.