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Search Results: 1 - 10 of 332081 matches for " Ivan S. Grudinin "
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Frequency combs from crystalline resonators: influence of cavity parameters on comb dynamics
Ivan S. Grudinin,N. Yu
Physics , 2014, DOI: 10.1117/1.OE.53.12.122609
Abstract: We experimentally study the factors that influence the span in frequency combs derived from the crystalline whispering gallery mode resonators. We observe that cavity dispersion plays an important role in generation of combs by cascaded four wave mixing process. We observed combs from the resonators with anomalous dispersion and nearly zero dispersion at the pump wavelength. In addition, the comb generation efficiency is found to be affected by the crossing of modes of different families. The influence of Raman gain is discussed as well as the role of cavity diameter and pump power. Copyright 2014 California Institute of Technology. Government sponsorship acknowledged.
Micro--structured crystalline resonators for optical frequency comb generation
Ivan S. Grudinin,Nan Yu
Physics , 2014,
Abstract: Optical frequency combs have recently been demonstrated in micro--resonators through nonlinear Kerr processes. Investigations in the past few years provided better understanding of micro--combs and showed that spectral span and mode locking are governed by cavity spectrum and dispersion. While various cavities provide unique advantages, dispersion engineering has been reported only for planar waveguides. In this Letter, we report a resonator design that combines dispersion control, mode crossing free spectrum, and ultra--high quality factor. We experimentally show that as the dispersion of a MgF2 resonator is flattened, the comb span increases reaching 700 nm with as low as 60 mW pump power at 1560 nm wavelength, corresponding to nearly 2000 lines separated by 46 GHz. The new resonator design may enable efficient low repetition rate coherent octave spanning frequency combs without the need for external broadening, ideal for applications in optical frequency synthesis, metrology, spectroscopy, and communications.
Impact of cavity spectrum on span in microresonator frequency combs
Ivan S. Grudinin,Lukas Baumgartel,Nan Yu
Physics , 2013, DOI: 10.1364/OE.21.026929
Abstract: We experimentally study the factors that limit the span in frequency combs derived from the crystalline whispering gallery mode resonators. We observe that cavity dispersion is the key property that governs the parameters of the combs resulting from cascaded four wave mixing process. Two different regimes of comb generation are observed depending on the precise cavity dispersion behavior at the pump wavelength. In addition, the comb generation efficiency is found to be affected by the crossing of modes of different families. The influence of Raman lasing is discussed.
Frequency comb from a microresonator with engineered spectrum
Ivan S. Grudinin,Lukas Baumgartel,Nan Yu
Physics , 2012,
Abstract: We demonstrate that by varying the ratio between the linewidth and dispersion of a whispering gallery mode resonator we are able to control the number N of free spectral ranges separating the first generated comb sidebands from the pump. We observed combs with N=19 and N=1. For the comb with N=1 we have achieved a span of over 200 nm using a 0.4 mm MgF2 resonator with a pump of 50 mW, which is a factor of 10 lower than previously reported.
Polarization conversion loss in birefringent crystalline resonators
Ivan S. Grudinin,Guoping Lin,Nan Yu
Physics , 2013, DOI: 10.1364/OL.38.002410
Abstract: Whispering gallery modes in birefringent crystalline resonators are investigated. We experimentally investigate the XY--cut resonators made with LiNbO$_3$, LiTaO$_3$ and BBO and observe strong influence of the resonator's shape and birefringence on the quality factor of the extraordinary polarized modes. We show that extraordinary modes can have lower Q and even be suppressed due to polarization conversion loss. The ordinary ray modes retain the high Q due to inhibited reflection phenomenon.
Waveguide couplers for ferroelectric optical resonators
Ivan S. Grudinin,A. Kozhanov,N. Yu
Physics , 2014,
Abstract: We report a study of using the same material to fabricate a whispering gallery mode resonator and a coupler. Coupling to high Q whispering gallery modes of the lithium niobate resonator is demonstrated by means of the titanium-doped waveguide. The waveguide coupling approach opens possibilities for simpler and wider practical usage of whispering gallery mode resonators and their integration into optical devices.
Brillouin Lasing with a CaF_2 Whispering Gallery Mode Resonator
Ivan S. Grudinin,Andrey B. Matsko,Lute Maleki
Physics , 2008, DOI: 10.1103/PhysRevLett.102.043902
Abstract: Stimulated Brillouin scattering with both pump and Stokes beams in resonance with whispering gallery modes of an ultra high Q CaF_2 resonator is demonstrated for the first time. The resonator is pumped with 1064 nm light and has a Brillouin lasing threshold of 3.5 microwatt. Potential applications include optical generation of microwaves and sensitive gyros.
Phonon laser action in a tunable, two-level photonic molecule
Ivan S. Grudinin,O. Painter,Kerry J. Vahala
Physics , 2009, DOI: 10.1103/PhysRevLett.104.083901
Abstract: The phonon analog of an optical laser has long been a subject of interest. We demonstrate a compound microcavity system, coupled to a radio-frequency mechanical mode, that operates in close analogy to a two-level laser system. An inversion produces gain, causing phonon laser action above a pump power threshold of around 50 $\mu$W. The device features a continuously tunable, gain spectrum to selectively amplify mechanical modes from radio frequency to microwave rates. Viewed as a Brillouin process, the system accesses a regime in which the phonon plays what has traditionally been the role of the Stokes wave. For this reason, it should also be possible to controllably switch between phonon and photon laser regimes. Cooling of the mechanical mode is also possible.
Enhanced photothermal displacement spectroscopy for thin-film characterization using a Fabry-Perot resonator
Eric D. Black,Ivan S. Grudinin,Shanti R. Rao,Kenneth G. Libbrecht
Physics , 2003, DOI: 10.1063/1.1728312
Abstract: We have developed a new technique for photothermal displacement spectroscopy that is potentially orders of magnitude more sensitive than conventional methods. We use a single Fabry-Perot resonator to enhance both the intensity of the pump beam and the sensitivity of the probe beam. The result is an enhancement of the response of the instrument by a factor proportional to the square of the finesse of the cavity over conventional interferometric measurements. In this paper we present a description of the technique, and we discuss how the properties of thin films can be deduced from the photothermal response. As an example of the technique, we report a measurement of the thermal properties of a multilayer dielectric mirror similar to those used in interferometric gravitational wave detectors.
Finite element modeling of coupled optical microdisk resonators for displacement sensing
Ivan Grudinin,Nan Yu
Physics , 2012, DOI: 10.1364/JOSAB.29.003010
Abstract: We analyze normal mode splitting in a pair of vertically coupled microdisk resonators. A full vectorial finite element model is used to find the eigen frequencies of the symmetric and antisymmetric composite modes as a function of coupling distance. We find that the coupled microdisks can compete with the best Fabry-Perot resonators in displacement sensing. We also show how we configured FreeFem++ for the sphere eigenvalue problem.
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