Michael Kozhevnikov

Bio: Michael Kozhevnikov is an academic researcher. The author has contributed to research in topics: Optical force & Whispering-gallery wave. The author has an hindex of 3, co-authored 4 publications receiving 161 citations.

Micro-optical force sensor concept based on whispering gallery mode resonators.

Abstract: A micro-optical force sensor concept based on the morphology-dependent shifts of optical modes of dielectric microspheres is investigated. The optical resonances, commonly referred to as the whispering gallery modes (WGM), were excited by evanescently coupling light from a tunable diode laser using a tapered single-mode fiber. A compressive force applied to the sphere induces a change in both the shape and the index of refraction of the sphere leading to a shift in WGM. By tracking the shifts, the force magnitude is determined using solid silica as well as solid and hollow Polymethyl-methacrylate (PMMA) microsphere resonators. A measurement sensitivity as high as dlambda/dF=7.664 nm/N was demonstrated with a 960 mum hollow PMMA sphere.

Optical Force Sensor Based on Whispering Gallery Mode Resonators

Abstract: This paper discusses a novel micro-optical force sensor based on dielectric microspheres that are excited by coupling light from optical fibers. The technique exploits the morphology-dependent shifts in resonant frequencies that are commonly referred to as the whispering gallery modes (WGM). A small change in the size, shape or optical constants of the microsphere causes a shift in the resonant frequency (or the WGM). For example, a compression force applied to the microsphere will lead to a change in both its shape and its index of refraction distribution. These changes will result in a shift of the WGM. By monitoring this shift, the magnitude of the applied force can be determined. The WGM shifts are observed by scanning a tunable diode laser that is coupled into the optical fiber on one end and monitoring the transmission spectrum by a photo diode on the other end. When the microsphere is in contact with a bare section of the fiber, the optical modes are observed as dips (due to destructive interference) in the intensity of the light transmitted through the fiber. Current results demonstrate the WGM shifts due to compression force applied to micro-spheres along the polar direction. The measurements also indicate a force measurement resolution of ~ 10 N with the current sensor design.

Performance of a Whispering Gallery Mode Resonator - Based Micro -Optical Force Sensor

Abstract: In this paper, we investigate the performance of a prototype micro -optical force sensor and discuss issues related to its sensitivity and calibration. The measurement concept is based on the shifts in the optical resonances of small dielectric spheres. The optical resonances, commonly referred to as t he whispering gallery modes (WGM), are excited by evanescently coupling light from a tunable diode laser using a tapered single mode fiber. The spheres are of the order of several hundred microns in diameter. The WGMs of the spheres are observed as sharp d ips in the transmission spectrum through the fiber. A compressive force applied to the sphere induces a change in both the shape and the index of refraction of the sphere. These changes, in turn, lead to a shift in the optical resonance (WGM). We built and analyzed the performance of micro -sensor prototypes using silica and polymer (Polymethyl Methacrylate or PMMA) dielectric spheres. In the case of PMMA, we used both solid and hollow spheres as sensor. The solid silica and hollow PMMA sensors offer the low est and highest measurements sensitivity, respectively. The silica sensors have the largest force range. As expected, smaller sensor sizes lead to increased sensitivity.

Whispering gallery mode sensors

Abstract: We present a comprehensive overview of sensor technology exploiting optical whispering gallery mode (WGM) resonances. After a short introduction we begin by detailing the fundamental principles and theory of WGMs in optical microcavities and the transduction mechanisms frequently employed for sensing purposes. Key recent theoretical contributions to the modeling and analysis of WGM systems are highlighted. Subsequently we review the state of the art of WGM sensors by outlining efforts made to date to improve current detection limits. Proposals in this vein are numerous and range, for example, from plasmonic enhancements and active cavities to hybrid optomechanical sensors, which are already working in the shot noise limited regime. In parallel to furthering WGM sensitivity, efforts to improve the time resolution are beginning to emerge. We therefore summarize the techniques being pursued in this vein. Ultimately WGM sensors aim for real-world applications, such as measurements of force and temperature, or alternatively gas and biosensing. Each such application is thus reviewed in turn, and important achievements are discussed. Finally, we adopt a more forward-looking perspective and discuss the outlook of WGM sensors within both a physical and biological context and consider how they may yet push the detection envelope further.

Spherical whispering‐gallery‐mode microresonators

Abstract: Whispering-gallery modes (WGM) on a spherical surface were first described by Lord Rayleigh at the beginning of the last century, but only after the invention of laser did they start to have some scientific relevance and only during the last two decades there has been a substantial move towards real devices and practical applications. WGM resonators have peculiar properties, the most notable being the potential of having an ultrahigh quality factor Q, which makes them very appealing both as laser cavities and as extremely sensitive sensors. Among the different types of WGM resonators, the microspherical ones represent a very important category, due to their simplicity, easy fabrication, and very high quality. In this review we provide a description of their fundamental properties and we summarize recent works on their application as filters, sensors and lasers.

Whispering gallery mode microresonators: Fundamentals and applications

Abstract: Confinement of light into small volumes has become an essential requirement for photonic devices; examples of this trend are provided by optical fibers, integrated optical circuits, semiconductor lasers, and photonic crystals. Optical dielectric resonators supporting Whispering Gallery Modes (WGMs) represent another class of cavity devices with exceptional properties, like extremely small mode volume, very high power density, and very narrow spectral linewidth. WGMs are now known since more than 100 years, after the papers published by John William Strutt (Lord Rayleigh), but their importance as unique tools to study nonlinear optical phenomena or quantum electrodynamics, and for application to very low-threshold microlasers as well as very sensitive microsensors, has been recognized only in recent years. This paper presents a review of the field of WGM resonators, which exist in several geometrical structures like cylindrical optical fibers, microspheres, microfiber coils, microdisks, microtoroids, photonic crystal cavities, etc. up to the most exotic structures, such as bottle and bubble microresonators. For the sake of simplicity, the fundaments of WGM propagation and most of the applications will be described only with reference to the most common structure, i.e. microspherical resonators.

WGM microresonators: sensing, lasing and fundamental optics with microspheres

Abstract: Glass microsphere resonators that support optical resonances known as whispering-gallery modes are unique tools for studying and exploiting optical effects under extremely well controlled conditions. In this paper, a review focusing mostly on glass microsphere resonators is presented. First, a brief historical background is given in which we see how the state-of-the-art has grown from novel optical resonators to the ultrahigh Q cavities used in cutting-edge experiments. After the basic properties of microsphere resonators are outlined we will discuss some of the recent experiments involving microsphere resonators, although some discussion involving polymeric microspheres is also included. The use of doped and undoped microspheres in optical signal processing, optical sensing and quantum optics is highlighted. Finally, there is a brief review of recent optomechanical experiments that use microspheres.

Whispering gallery microsensors: a review

Abstract: Optical whispering gallery mode (WGM) microresonators, confining resonant photons in a microscale resonator for long periods of time, could strongly enhance light-matter interaction, making it an ideal platform for all kinds of sensors. In this paper, an overview of optical sensors based on WGM microresonators is comprehensively summarized. First, the fundamental sensing mechanisms as well as several recently developed enhanced sensing techniques are introduced. Then, different types of WGM structures for sensing as well as microfluidics techniques are summarized. Furthermore, several important sensing parameters are discussed. Most importantly, a variety of WGM sensing applications are reviewed, including both traditional matter sensing and field sensing. Last, we give a brief summary and perspective of the WGM sensors and their role in future applications.