Origin of emission from square-shaped organic microlasers

Abstract

The emission from open cavities with non-integrable features remains a challenging problem of practical as well as fundamental relevance. Square-shaped dielectric microcavities provide a favorable case study with generic implications for other polygonal resonators. We report on a joint experimental and theoretical study of square-shaped organic microlasers exhibiting a far-field emission that is strongly concentrated in the directions parallel to the side walls of the cavity. A semiclassical model for the far-field distributions is developed that is in agreement with even fine features of the experimental findings. Comparison of the model calculations with the experimental data allows the precise identification of the lasing modes and their emission mechanisms, providing strong support for a physically intuitive ray-dynamical interpretation. Special attention is paid to the role of diffraction and the finite side length.

Excitation Position Sensitive Upconversion Emission of Lanthanide Ions Doped β‐NaYF4 Single Microcrystals

“…If the laser beam is shifted to one end, the emissions at both ends are observed. This phenomenon can be attributed to the waveguide effect associated with the reflection, total internal reflection, and diffraction of the emission light at the interface between the microcrystal and air ,. The proposed light propagation path in a microrod is showed in the right part of Figure a.…”

“…The proposed light propagation path in a microrod is showed in the right part of Figure a. The critical angle of the interface of NaYF 4 and air is 44.4° according to Snell's law ,. The emission light can be scattered out of the ends when the incident angle at the crystal‐air interface is less than 44.4°.…”

“…The emission light can be scattered out of the ends when the incident angle at the crystal‐air interface is less than 44.4°. When the incident angle is larger than 44.4°, the full light beam will be continuously reflected until losing in the crystal completely except an evanescent wave propagating along the interface and scattering out of the crystals . When the light from the excitation or reflected from the ends reaches sharp corners, most of the light will be scattered to far field with bright output beams due to the pseudointegrable leakage ,.…”

Mode Q factor and lasing spectrum controls for deformed square resonator microlasers with circular sides

“…PACS: 42.55.Sa, 42.55.Px, 42.60.Da, OFC was traditionally generated using femtosecond mode-locked lasers [19, 25, and 26]. The generations of OFC in ultrahigh-Q microresonator have triggered intensive researches of four-wave mixing (FWM) in the microresonator under a continuous-wave laser pumping [27][28][29], and cascaded FWM in the nonlinear optical fiber has also been utilized for generating frequency combs via the pumping of two single-frequency lasers [30][31][32].Recently, square resonators have received a great deal of interest for single-mode lasing and enhancement of mode Q factors [33][34][35][36]. Dual-mode lasing with a tunable wavelength interval was demonstrated for square resonator microlasers with a patterned electrode and a vertex waveguide [33].…”

“…Recently, square resonators have received a great deal of interest for single-mode lasing and enhancement of mode Q factors [33][34][35][36]. Dual-mode lasing with a tunable wavelength interval was demonstrated for square resonator microlasers with a patterned electrode and a vertex waveguide [33].…”