Spectral and directional properties of elliptical quantum-dot microlasers

Abstract. We have fabricated microdisk lasers of colloidal quantum dots in circular and elliptical forms with different aspect ratios. By characterizing the laser emission spectrum under optical pumping and through mode simulation calculations, we demonstrate that the elliptical resonators can display two sets of whispering-gallery modes that interact to varying degrees depending on the aspect ratio. This causes significant mode splitting in the emission spectra when the mode interaction is at maximum. We also performed angular-dependent laser emission measurements for characterizing the emission pattern of the microlasers. We found that the emission pattern becomes less isotropic and more directional as the boundary deviates further from circular symmetry. In addition, we demonstrate that the emission directional properties of these microlasers can be further tailored by coupling pairs of elliptical microcavities together in different manners, where the long or short elliptical axis interacts most strongly.

[1]  M. Berry,et al.  Regularity and chaos in classical mechanics, illustrated by three deformations of a circular 'billiard' , 1981 .

[2]  V. Apalkov,et al.  Directional emission from a microdisk resonator with a linear defect , 2004 .

[3]  Lan Yang,et al.  Whispering gallery microcavity lasers , 2013 .

[4]  Wavelength-scale deformed microdisk lasers , 2011 .

[5]  Hui Cao,et al.  Dielectric microcavities: Model systems for wave chaos and non-Hermitian physics , 2015 .

[6]  Shiyue Hua,et al.  Parity–time symmetry and variable optical isolation in active–passive-coupled microresonators , 2014, Nature Photonics.

[7]  Songky Moon,et al.  Observation of an exceptional point in a chaotic optical microcavity. , 2009, Physical review letters.

[8]  K. Vahala,et al.  Modal coupling in traveling-wave resonators. , 2002, Optics letters.

[9]  Rajan P Kulkarni,et al.  Label-Free, Single-Molecule Detection with Optical Microcavities , 2007, Science.

[10]  D. Christodoulides,et al.  Parity-time–symmetric microring lasers , 2014, Science.

[11]  Federico Capasso,et al.  Whispering-gallery mode resonators for highly unidirectional laser action , 2010, Proceedings of the National Academy of Sciences.

[12]  T. J. Kippenberg,et al.  Ultra-high-Q toroid microcavity on a chip , 2003, Nature.

[13]  Sidney T. Malak,et al.  Large‐Scale Robust Quantum Dot Microdisk Lasers with Controlled High Quality Cavity Modes , 2017 .

[14]  Sidney T. Malak,et al.  Core/Alloyed-Shell Quantum Dot Robust Solid Films with High Optical Gains , 2016 .

[15]  Cho,et al.  High-power directional emission from microlasers with chaotic resonators , 1998, Science.

[16]  Shanhui Fan,et al.  Parity–time-symmetric whispering-gallery microcavities , 2013, Nature Physics.

[17]  R. Polson,et al.  Directional emission from asymmetric microlaser resonators of π-conjugated polymers , 2004 .

[18]  Lan Yang,et al.  On-chip single nanoparticle detection and sizing by mode splitting in an ultrahigh- Q microresonator , 2010 .

[19]  K. Vahala,et al.  Ideality in a fiber-taper-coupled microresonator system for application to cavity quantum electrodynamics. , 2003, Physical review letters.

[20]  A. F. J. Levi,et al.  Whispering-gallery mode microdisk lasers , 1992 .

[21]  Y. Wang,et al.  Single-mode laser by parity-time symmetry breaking , 2014, Science.