title: Near-field imaging of quantum cascade laser transverse modes.
abstract: We report near field imaging of the transverse lasing modes of quantum cascade lasers. A mid-infrared apertureless near-field scanning optical microscope was used to characterize the modes on the laser facet. A very stable mode pattern corresponding to a TM(00) mode was observed as function of increasing driving current for a narrow active region quantum cascade laser. Higher order modes were observed for devices with a larger active region width-to-wavelength ratio operated in pulsed mode close to threshold. A theoretical model is proposed to explain why specific transverse modes are preferred close to threshold. The model is in good agreement with the experimental results.
authors: Nanfang
authors: N
authors: Yu
authors: Laurent
authors: L
authors: Diehl
authors: Ertugrul
authors: E
authors: Cubukcu
authors: Christian
authors: C
authors: Pflügl
authors: David
authors: D
authors: Bour
authors: Scott
authors: S
authors: Corzine
authors: Jintian
authors: J
authors: Zhu
authors: Gloria
authors: G
authors: Höfler
authors: Kenneth B
authors: KB
authors: Crozier
authors: Federico
authors: F
authors: Capasso