24 research outputs found
Measurement of absolute radius, refractive index and dispersion of a long cylinder
Long cylinders, such as optical fibers, are some of the most widely used
photonic devices. The radius and refractive index of these fibers are therefore
fundamentally important parameters in determining their performance. We have
developed a method to determine the absolute radius, refractive index, and
chromatic dispersion of a long cylinder using only the resonance wavelengths of
the whispering gallery modes around its circumference for two different
polarizations. Since this method only requires the measurement of resonance
wavelengths, it is non-destructive and it can be performed using standard
equipment. As a proof-of-concept, we demonstrate the method on a
optical fiber and an borosilicate capillary fiber with thick walls,
obtaining values for the diameter and the refractive index with an accuracy of
and , respectively.Comment: 10 pages, 5 figures; Correction to name in reference and typo;
removed line number
Wavelength shift in a whispering gallery microdisk due to bacterial sensing: a theoretical approach
Whispering gallery mode microcavities have recently been studied as a means to achieve real-time label-free detection of biological targets such as virus particles, specific DNA sequences, or proteins. Binding of a biomolecule to the surface of a microresonator will increase its path length, leading to a shift in the resonance frequency according to the reactive sensing principle. In this paper, we develop a theoretical expression that will link the reactive shift to the bacteria and microdisk parameters and help quantify the number of bacteria that bind to the surface of a 200μm-diameter silica microdisk
Observation of simultaneous fast and slow light
We present a microresonator-based system capable of simultaneously producing
time-advanced and time-delayed pulses. The effect is based on the combination
of a sharp spectral feature with two orthogonally-polarized propagating
waveguide modes. We include an experimental proof-of-concept implementation
using a silica microsphere coupled to a tapered optical fiber and use a
time-domain picture to interpret the observed delays. We also discuss potential
applications for future all-optical networks.Comment: 6 pages, 5 figure
Slow light in mass-produced, dispersion-engineered photonic crystal ring resonators
We present experimental results of photonic crystal ring resonators (PhCRRs) fabricated on the CMOS-compatible, silicon-on-insulator platform via 193-nm deep-UV lithography. Our dispersion-engineering design approach is compared to experimental results, showing very good agreement between theory and measurements. Specifically, we report a mean photonic band-edge wavelength of 1546.2 ± 5.8 nm, a 0.2% variation from our targeted band-edge wavelength of 1550 nm. Methods for the direct calculation of the experimental, discrete dispersion relation and extraction of intrinsic quality factors for a highly-dispersive resonator are discussed. A maximum intrinsic quality factor of ≈83,800 is reported, substantiating our design method and indicating that high-throughput optical lithography is a viable candidate for PhCRR fabrication. Finally, through comparison of the mean intrinsic quality and slowdown factors of the PhCRRs and standard ring resonators, we present evidence of an increase in light-matter interaction strength with simultaneous preservation of microcavity lifetimes
Quantum computers in phase space
We represent both the states and the evolution of a quantum computer in phase
space using the discrete Wigner function. We study properties of the phase
space representation of quantum algorithms: apart from analyzing important
examples, such as the Fourier Transform and Grover's search, we examine the
conditions for the existence of a direct correspondence between quantum and
classical evolutions in phase space. Finally, we describe how to directly
measure the Wigner function in a given phase space point by means of a
tomographic method that, itself, can be interpreted as a simple quantum
algorithm.Comment: 16 pages, 7 figures, to appear in Phys Rev
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Optical resonators and quantum dots: and excursion into quantum optics, quantum information and photonics
textModern communications technology has encouraged an intimate connection between Semiconductor Physics and Optics, and this connection shows best in the combination of electron-confining structures with light-confining structures. Semiconductor quantum dots are systems engineered to trap electrons in a mesoscopic scale (the are composed of [approximately] 10000 atoms), resulting in a behavior resembling that of atoms, but much richer. Optical microrseonators are engineered to confine light, increasing its intensity and enabling a much stronger interaction with matter. Their combination opens a myriad of new directions, both in fundamental Physics and in possible applications. This dissertation explores both semiconductor quantum dots and microresonators, through experimental work done with semiconductor quantum dots and microsphere resonators spanning the fields of Quantum Optics, Quantum Information and Photonics; from quantum algorithms to polarization converters. Quantum Optics leads the way, allowing us to understand how to manipulate and measure quantum dots with light and to elucidate the interactions between them and microresonators. In the Quantum Information area, we present a detailed study of the feasibility of excitons in quantum dots to perform quantum computations, including an experimental demonstration of the single-qubit Deutsch-Jozsa algorithm performed in a single semiconductor quantum dot. Our studies in Photonics involve applications of microsphere resonators, which we have learned to fabricate and characterize. We present an elaborate description of the experimental techniques needed to study microspheres, including studies and proof of concept experiments on both ultra-sensitive microsphere sensors and whispering gallery mode polarization converters.Physic
Optical Microbottle Resonators for Sensing
Whispering gallery mode (WGM) optical microresonators have been shown to be the basis for sensors able to detect minute changes in their environment. This has made them a well-established platform for highly sensitive physical, chemical, and biological sensors. Microbottle resonators (MBR) are a type of WGM optical microresonator. They share characteristics with other, more established, resonator geometries such as cylinders and spheres, while presenting their unique spectral signature and other distinguishing features. In this review, we discuss recent advances in the theory and fabrication of different kinds of MBRs, including hollow ones, and their application to optofluidic sensing
Optical Microbottle Resonators for Sensing
Whispering gallery mode (WGM) optical microresonators have been shown to be the basis for sensors able to detect minute changes in their environment. This has made them a well-established platform for highly sensitive physical, chemical, and biological sensors. Microbottle resonators (MBR) are a type of WGM optical microresonator. They share characteristics with other, more established, resonator geometries such as cylinders and spheres, while presenting their unique spectral signature and other distinguishing features. In this review, we discuss recent advances in the theory and fabrication of different kinds of MBRs, including hollow ones, and their application to optofluidic sensing