Observation of green lasing at 537 nm from Er-ions by coupled photon–atom modes in a random cavity

Van Hoi Pham, Thuy Chi Do, Huy Bui, The Anh Nguyen and Thuy Van Nguyen

Abstract

We present new results of a laser phenomenon that gives rise to a narrow green emission mode in a random photonic-crystal cavity based on an Er-doped glass–air gap–polymer with a 976 nm diode laser pump. Lasing occurs at 537 nm, which does not respond to the resonant radiative transition ²H_11/2→⁴I_15/2; ⁴S_3/2→⁴I_15/2 in Erbium ions. This effect can be seen as photon–atom coupling in the context of the interaction between a single atom and/or a few atoms and resonant optical media, such as cavities or photonic crystals. Experimental results show that the random lasing mode directly originates from the coupled photon–atom mode inside the random cavity. The measured Q-factor is of 2100–2800 for a random cavity with an air gap of 600–1700 nm between Er-doped glass fiber and a coated polymer layer