Optical cavity

A promising technique is cavity ringdown laser absorption spectroscopy (307), in which the rate of decay of laser pulses injected into an optical cavity containing the sample is measured. Absorption sensitivities of 5 x 10 have been measured on a ]ls time scale. AppHcations from the uv to the ir... 

The word laser is an acronym for light amplification by the stimulated emission of radiation. Lasers of all kinds consist of several basic components an active medium, an outside energy source, and an optical cavity with carefully designed mirrors on both ends. One of the mirrors is 100 percent reflective... 

As the emitted radiation bounces back and forth between the two mirrors, it becomes coherent. Some of the energy traveling back and forth through the optical cavity is transmitted though the less reflective mirror and becomes a laser beam. 

It is well known that by inserting an optical amplifier obtained by population inversion in an optical cavity, one can realize sources of coherent radiations, namely lasers. One can operate in the same way with parametric amphfication as shown on Fig. 1. A nonlinear crystal illuminated by an input pump is inserted in an optical cavity. This cavity is represented for convenience as a ring cavity but consists usually of a linear cavity. An important difference with the laser is that there are three different fields, insfead of one, which are presenf in the amplifying medium, all these fields being able to be recycled by the cavity mirrors. One obtain thus different types of "Optical Parametric Oscillators" or OPOs. 

A laser consists in a medium where stimulated emission dominates over spontaneous emission placed inside an optical cavity which recycles the optical field. Above threshold, the photon number probability density distribution is poissonian, that means that the photon arrival time are a random variable. The probability of obtaining m photons during a given time interval is thus... 

The main hardware types offered by physics are mentioned, namely trapped ions (or trapped atoms), quantum dots, quantum optical cavities, rf superconducting quantum interference devices (SQUIDs) and nitrogen-vacancy (NV) defects on diamond. Some are important simply as a benchmark to evaluate the quality of the implementations offered by chemistry, whereas others might be combined with lanthanide complexes to produce heterogeneous quantum information processors which combine the advantages of different hardware types. 

Photons in quantum optical cavities also constitute excellent qubit candidates [52]. Resonant coupling of atoms with a single mode of the radiation field was experimentally achieved 25 years ago [53], and eventually the coherent coupling of quantum optical cavities with atoms or (simple) molecules was suggested as a means to achieve stable quantum memories in a hybrid quantum processor [54]. There might be a role to play for molecular spin qubits in this kind of hybrid quantum devices that combine solid-state with flying qubits. 

De Martini, F., Innocenti, G., Jacobovitz, G.R. and Mataloni, P. (1987) Anomalous spontaneous emission time in a microscopic optical cavity. Phys. Rev. Lett., 59, 2955-2958. 

Blair, S. Chen, Y., Resonant enhanced evanescent wave fluorescence biosensing with cylin drical optical cavities, Appl. Opt. 2001, 40, 570 582... 

Abstract The self-organized and molecularly smooth surface on liquid microdroplets makes them attractive as optical cavities with very high quality factors. This chapter describes the basic theory of optical modes in spherical droplets. The mechanical properties including vibrational excitation are also described, and their implications for microdroplet resonator technology are discussed. Optofluidic implementations of microdroplet resonators are reviewed with emphasis on the basic optomechanical properties. 

Freely suspended liquid droplets are characterized by their shape determined by surface tension leading to ideally spherical shape and smooth surface at the subnanometer scale. These properties suggest liquid droplets as optical resonators with extremely high quality factors, limited by material absorption. Liquid microdroplets have found a wide range of applications for cavity-enhanced spectroscopy and in analytical chemistry, where small volumes and a container-free environment is required for example for protein crystallization investigations. This chapter reviews the basic physics and technical implementations of light-matter interactions in liquid-droplet optical cavities. 

Optical absorption, of hydrogenated and hydrogen- free films, 17 206 Optical amplifiers, 11 145-146 Optical applications U.S. patents in, 12 614t of vitreous silica, 22 440-441 Optical cavities, 14 849 Optical cells, for high pressure measurements, 13 417-419 Optical coatings, cerium application,... 

An optical microcavity produced by the latter process has been applied to tune the emission from erbium-doped PS [Zh6], Erbium compounds like Er203 are known to exhibit a narrow emission band at 1.54 pm, which is useful for optical telecommunications. Several methods have been used to incorporate erbium in PS. A simple and economical way is cathodic electrochemical doping. External quantum efficiencies of up to 0.01% have been shown from erbium-doped PS films under electrical excitation [Lo2]. The emission band, however, is much broader than observed for Er203. This drawback can be circumvented by the use of an optical cavity formed by PS multilayers. In this case the band is narrowed and the intensity is increased because emission is only allowed into optical cavity modes [Lo3]. 

Enhancement of the Hght-matter interaction in a microscopic optical cavity is achieved because Hght trapped in the cavity has longer effective interaction time with absorbers. For short laser pulses, cavity length exceeding CTp allows avoidance of the interference between the pulses incident and reflected from the mirrors. Spectral selectivity of planar Fabry-Perot cavities can be used to achieve the localization at the resonant wavelength of the cavity. 

The photon thus induced to be emitted has the same phase relationship as the inducing photon. Further amplification of this coherent emission is brought about in a resonant optical cavity containing two highly reflecting mirrors, one of which allows the amplified beam to come out, either through a pin-hole or by a little transmission (Section 10.4). 

Once this emissive condition is established, the coherent emitted radiation is made to stimulate further emission from the excited atoms in an optical cavity in order to amplify the intensity of the phase coherent radiation. 

West and Berry (1037) have observed laser emissions due to the transition ( N(42n - Ar2 ) in the vacuum ultraviolet flash photolysis of C2N2, HCN, CICN, BrCN, and ICN. The CN(/42F1) radicals are produced within a low-loss optical cavity for effective laser action. 

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