Makan Mohageg

Morphology-dependent photonic circuit elements

We theoretically propose and experimentally demonstrate the design of a novel one-dimensional ringlike macroscopic optical circuit element. The similarity between morphologies of an optical planar waveguide and a whispering-gallery axially symmetric solid-state resonator is used.

Parametric oscillations in a whispering gallery resonator

We demonstrate strongly nondegenerate optical continuous-wave parametric oscillations in crystalline whispering gallery mode resonators fabricated from LiNbO3. The required phase matching is achieved by geometrical confinement of the modes in the resonator.

Ringdown spectroscopy of stimulated Raman scattering in a whispering gallery mode resonator

We report experimental observations of power-dependent, nonexponential decay of light stored in whispering gallery modes caused by stimulated Raman scattering in the resonator host material. Specifically, we show that the instantaneous decay rate of whispering gallery modes of a calcium fluoride resonator increases as the amount of light stored in the resonator decreases.

Calligraphic poling of Lithium Niobate

We demonstrate a novel technique for instituting complex and arbitrary shaped micron-scale domain patterns in LiNbO3 at room temperature. Fabrication of continuous domains as narrow as 2 microm across and hexagonal patterns of the same order accompanied by real time visualization of the poling process are presented.

Efficient generation of truncated Bessel beams using cylindrical waveguides

In this paper we address efficient conversion between a Gaussian beam (a truncated plane wave) and a truncated Bessel beam of a given order, using cylindrical optical waveguides and whispering gallery mode resonators. Utilizing a generator based on waveguides combined with whispering gallery mode resonators, we have realized Bessel beams of the order of 200 with a conversion efficiency exceeding 10 %.

High-Q optical whispering gallery modes in elliptical LiNbO 3 resonant cavities

We have experimentally demonstrated the existence of optical whispering-gallery-modes (WGMs) with quality factors in excess of 10(8) in elliptical cavities fabricated with LiNbO(3). The efficiency of evanescent coupling to the modes through a diamond prism was as high as 97.3%. This is the best value ever achieved for evanescent coupling to a WGM resonator using a prism. The free spectral ranges of the WGMs are successfully modeled using an eikonal approximation.

GPS test of the local position invariance of Planck's constant

Publicly available data on satellite positions and clock corrections for the Global Positioning System was analyzed and used in combination with the results of prior terrestrial clock comparison experiments to confirm the time dilation of general relativity for atomic and cryogenic resonator clocks. A model for testing local position invariance (LPI) in the context of general relativity was developed and used to confirm that Plancks constant

Lasing and up conversion from a nominally pure whispering gallery mode resonator

h

All-optical photonic oscillator with high-Q whispering gallery mode resonators

is invariant within a limit of

Coherent backscattering in lithium niobate whispering-gallery-mode resonators.

|\beta_h|<0.007