Controlling deformation in a high quality factor silica microsphere toward single directional emission

Abstract

High-Q deformed silica microsphere cavities are fabricated by short CO(2) laser pulses, where the deformation is well controlled by adjusting the intensity and number of pulses. Using this method, directional emission from whispering-gallery mode (WGM) with a high quality factor of 10(7) in these microspheres is achieved, and a transition from two-directional to single-directional emission is observed. Such concentrated directional emission and high-Q of WGMs show high potential for future studies of the chaotic ray dynamics in deformed microcavity and cavity quantum electrodynamics and optomechanics.

Stand-Off Biodetection with Free-Space Coupled Asymmetric Microsphere Cavities

“…However, despite these KAM curves, high-Q modes, such as WGMs, can still be measured in the far field of ARCs. Free-space excitation of high Q WGMs in ARCs is possible due to “chaos assisted dynamical tunneling,” and is evidenced form the observation of coupled mode effects [ 19 , 20 , 21 , 22 , 31 , 39 ], which we explain in the following and which are supported by our experimental data.…”

“…This positive result for SF6 agrees with the hypothesis made in Section 2.1 , but the high number of poles in the boundary is surprising. Most literature up to date, which has not yet directly imaged the emission pattern, has only measured ARCs with either two or four emission directions in the far field theoretically defined by quadrupole or half-quadrupole-half-circle boundaries [ 21 , 35 , 39 , 40 ]. However, the observed 6‒7 pole emission was repeatable and can be explained due to a resonator boundary with a six pole shape, created through the CO 2 laser pulse technique, where each laser pulse creates a unique dent in the boundary responsible for a certain number of distinct poles [ 23 ].…”

Whispering‐gallery microcavities with unidirectional laser emission

“…Recently, face‐shaped microcavities with large deformation of 18% have also been realized by Shao et al, which is beneficial to achieve high free‐space coupling efficiency and increase the localization of the emission . Besides, Liu et al and Cui et al have experimentally demonstrated the face‐shaped cavity microdisk by two‐photon polymerization and the microsphere fabricated by short CO 2 laser pulses , respectively. Very recently, Schermer et al reported the low‐index polymer microlasers with the short egg shape, which exhibits lasing modes with highly directional emission .…”

Fabrication and spectral characterizations of high Q asymmetric resonant cavities

“…In our experiment, the light transfer from the fiber taper to the microsphere based on the evanescent field. The distance/gap of the tapered fiber to the microsphere can changing the WGMs effect and lead to an inaccurate testing results [24]. Avoiding the fiber taper lateral moving by the mechanical perturbation and the flow of surrounding air, the fiber taper have been tightly affixed to surface of cavity and working in over coupling state.…”