Some characteristics of stimulated emission from thin-film lasers with adjoining amplifying media

A comparative study was made of the characteristics of stimulated emission from thin-film lasers in the form of an amplifying waveguide layer or in the form of a waveguide with an adjoining amplifying medium (WAAM). The advantage of the WAAM laser was the technological separation of the fabrication of waveguide and amplifying layers. The amplifying media were liquid and polymer films activated with rhodamine 6G. It was found that, in contrast to lasers with active waveguide layers, the WAAM lasers emitted mainly high-order transverse modes. The threshold optical pump powers for both types of laser could be similar.