Coupled-microdisk photonic molecules with high-symmetry geometries that support nondegenerate whispering gallery modes with high quality factors are numerically designed, based on a two-dimensional model. Dramatic enhancement of calculated Q factors of nondegenerate modes as compared with single-microdisk whispering gallery modes of the same radial order is achieved by tuning the intercavity coupling distances. Potential applications of this work to the design of single-mode coupled-microdisk structures with large spontaneous emission factors and low threshold lasing operation and to random laser simulations are discussed. 相似文献
We design coupled optical microcavities and report directional light emission from high-Q modes for a broad range of refractive indices. The system consists of a circular cavity that provides a high-Q mode in the form of a whispering gallery mode, whereas an adjacent deformed microcavity plays the role of a waveguide or collimator of the light transmitted from the circular cavity. As a result of this very simple, yet robust, concept we obtain high-Q modes with promising directional emission characteristics. No information about phase space is required, and the proposed scheme can be easily realized in experiments. 相似文献
A multi-wavelength microsphere laser system, using a chirped fibre Bragg grating and a microsphere resonator as wavelength-selective elements and a high dopant erbium doped fibre as the gain material, has been successfully demonstrated. The multi-wavelength generation of the laser system arises from both the microsphere whispering gallery mode selection and from the additional Raman scattering inside the microsphere cavity when the erbium laser is operating at resonance with the whispering gallery modes. Through an appropriate design and fabrication of a microsphere and of a fibre taper, a selective multi-wavelength fibre laser has been realized when the pump power is above threshold required. The laser output lines created have shown much narrower linewidths than those from conventional fibre lasers and these characteristics are particularly suitable for the range of sensor applications envisaged in the work. 相似文献
The quantum interpretation of whispering gallery modes in a cylindrical optical microcavity is presented in analogy with quantum mechanical theory. The formulas for the resonance shifts caused by a small change in correlative refractive index are derived. Then they are applied to two applications of the cylindrical microcavity to probe the change of surrounding medium and the nonlinear effect of cavity's surface. 相似文献
We demonstrate an approach to creating localized whispering gallery mode (WGM) microcavities by exploiting the photosensitivity of a chalcogenide (As2S3) microfiber. A highly prolate WGM microcavity with cavity quality factors (Q) exceeding 2×10(5) is fabricated and characterized. Without the need for geometrical shaping, our approach enables the cavity properties to be monitored during fabrication for the first time. 相似文献
We consider a significant lowering of the threshold of stimulated Raman scattering in solid fused silica spherical microlenses
cavities that is caused by an increase in the integral overlap factor of whispering gallery modes. The structure of focal
regions of a microlens is shown to have the shape of honeycombs, forming a photonic crystal or a photonic nanojet. We show
that, at comparatively small numerical apertures NA = 0.7–0.8, which correspond to hemispherical microlenses, a spherical microlens cavity exhibits the possibility of focusing
laser radiation beyond the Abbe diffraction limit. This enables the possibility of wide practical applications of microspheres
as a focusing element the resolving power of which exceeds the Abbe diffraction limit in the near field. The whispering-gallery-mode
spherical microlens cavity makes it possible to perform laser generation with a duration of a coherent pulse in the subfemtosecond
range and to form a subwavelength focal region of the near field. This ensures the possibility of detecting single molecules
of a substance in the subwavelength range in the near field and can be used to increase the sensitivity of intracavity spectroscopy
methods and as microlasers for excitation of molecules in metal molecular nanoswitches and semiconductor heterostructures.
From an array of microlens cavities, metamaterials with a negative refractive index can be formed. 相似文献
Whispering gallery modes in cylindrical integrated optics microcavities have, for what is to our knowledge the first time, been mapped with a photon scanning tunneling microscope. Optical images were obtained with a spatial resolution of 50 nm. By combination of information on the spatial optical distributions with wavelength-dependent measurements, an unexpectedly rich variety of intracavity phenomena, such as polarization conversion and interference of copropagating and counterpropagating modes, could be directly observed. A quantitative comparison of the experimental data with computer simulations results in a comprehensive understanding of the various whispering gallery modes inside the microcavity. 相似文献
In this paper, whispering gallery mode solvers based on a set of corresponding straight waveguide modes are proposed. The solvers project whispering gallery modes onto a linear combination of straight waveguide modes through a cavity residual operator eigensolution formalism and direct straight waveguide expansion procedures. With these implementations, a perfectly matched layer can be imposed at the cavity computation window edges automatically and optical properties of plain and metal coated silica microtoroids can be analyzed from a novel viewpoint. Additionally, the techniques can be employed in cavity mode matching methods for the modelling of cavities that strongly scatter light. 相似文献
Optical fibers of 12 μm diameter were coated with a sputter-deposited layer (4 μm thick) of titanium (1 at. %)-doped amorphous aluminum nitride. When optically pumped by an Nd:YAG green laser at 532 nm, laser action was observed in whispering gallery modes around the fiber (in a ring shape) at 780.5 nm with a quality factor Q > 1500. Other modes were also observed between 775 and 800 nm. The primary and secondary modes give a mode separation of 4.6 nm. No waveguide modes were observed in the cavity. 相似文献
The emissivity of unstrained quantum-dimensional InP/AlInAs nanostructures and their lasing properties in microdisk cavities prepared by wet etching have been studied. For as-prepared structures, it has been found that they radiate owing to quantum-dimensional InP islands 50–300 nm in diameter. At temperatures below 160 K, whispering gallery modes have been observed in the microdisks. Experimental data on the PL intensity for microcavity modes versus the pump power, which were obtained at liquid helium temperature, have made it possible to find the lasing threshold, 50 W/cm2. The half-width of the laser line at above-threshold powers equals 0.06 nm, which corresponds to a Q factor of 15 000. 相似文献
Results of investigations into the spectral and power characteristics of two-photon fluorescence of a liquid drop with the Rhodamine 6G dye irradiated by femtosecond laser pulses are presented. It is demonstrated that stimulated emission of two types is realized in drops with the concentrated dye solution, namely, superfluorescence within the drop volume and lasing on whispering gallery modes.__________Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 4, pp. 15–19, April, 2005. 相似文献
We report on the observation of a mode-locked laser generated with a crystalline whispering gallery mode resonator pumped with a continuous wave laser. Optical pumping of the resonator generates an optical frequency comb with phase locked components at the Raman offset of the resonator host material. Phase locking of the modes is confirmed via measurement of the radio-frequency beat note produced by the comb on a fast photodiode. Neither the conventional Kerr comb nor hyperparametric oscillation is observed when the comb is present. We present a theoretical explanation of the effect. 相似文献
A theoretical model that describes the transformation of electromagnetic radiation by microcavities in the form of microspheres
with a semiconductor nanostructure shell is developed. It is established that the regime of bistable two-mode laser oscillation
due to morphology-dependent resonances with different quality factors and spatial distributions of the electromagnetic field
can be implemented in a two-layer microcavity with a semiconductor-nanostructure shell. The region of two-mode oscillation
and the relation between the intensities of oscillating modes depend on the indices of refraction and the sizes of the microparticle
core and shell. 相似文献
Optical whispering‐gallery mode (WGM) microcavities featuring ultrahigh Q factors and small mode volumes enhance significantly the interaction between light and matter, becoming an excellent platform for achieving ultralow‐threshold microlasers. However, the emission of traditional WGMs is isotropic due to the rotational symmetry of cavity geometries, which hinders the potential photonics applications. In this review, the progress in WGM microcavities towards unidirectional laser emission is summarized. When a subwavelength scatterer is placed on the boundary of the microcavity, the unidirectional emission occurs due to the collimation effect of the microcavity‐enhanced scattering field. Furthermore, microcavities deformed from the circular shapes can not only produce the chaos‐assisted unidirectional emission, but also maintain high Q factors by special design and fabrication processes. Finally, gratings along the circumference of the WGM microdisk or microring can scatter the WGMs in the vertical direction. The review also lists several important applications of these types of microcavities, such as wide‐band laser illumination source, free‐space coupling, evanescent‐field enhancement, optical energy storage, and sensing.