Whispering- Gallery Mode Silica Micro-Sensors for Temperature and Gas-Phase Concentration Measurements

** † ‡ Temperature measurement utilizing Whispering Gallery Modes (WGM) in silica microspheres is analytically and experimentally studied over a wide range of temperature, cryogenic (~110K) to above room temperatures (310K). Experimental results using a resonance wavelength shift technique show excellent sensitivity and repeatability for point temperature measurements as well as the capability for ultrahigh-resolution operation. Gas phase molecular detection utilizing spectra shift of WGM is also shown for coated microspheres. Mie theory analysis is utilized to explain coating sensitivity. A demonstration experiment is realized using a hydrophilic SiO 2 nanoparticle coating on the microsphere. High measurement resolution (1ppm H 2 O change) at low humidity levels (0%~10%) is seen which far exceeds previous studies based on the similar coating techniques.

[1]  Douglas B. Leviton,et al.  Temperature-dependent absolute refractive index measurements of synthetic fused silica , 2006, SPIE Astronomical Telescopes + Instrumentation.

[2]  T. J. Kippenberg,et al.  Ultra-high-Q toroid microcavity on a chip , 2003, Nature.

[3]  Chi-En Lu,et al.  Humidity Sensors: A Review of Materials and Mechanisms , 2005 .

[4]  K. Vahala,et al.  Fiber-coupled microsphere laser. , 2000, Optics letters.

[5]  Stanley Pau,et al.  Near-field gap effects on small microcavity whispering-gallery mode resonators , 2006 .

[6]  J. Raimond,et al.  Very low threshold whispering-gallery-mode microsphere laser. , 1996, Physical review. A, Atomic, molecular, and optical physics.

[7]  N. Gupta,et al.  Analysis of an encapsulated whispering gallery mode micro-optical sensor , 2009 .

[8]  S. Shopova,et al.  Cavity-enhanced laser absorption spectroscopy using microresonator whispering-gallery modes. , 2007, Optics express.

[9]  J Greve,et al.  Sensor based on an integrated optical microcavity. , 2002, Optics letters.

[10]  Zhixiong Guo,et al.  Simulation of whispering-gallery-mode resonance shifts for optical miniature biosensors , 2005 .

[11]  M. Bouazaoui,et al.  Optical fibre temperature sensor in the cryogenic range , 1996 .

[12]  D. Braun,et al.  Multiplexed DNA quantification by spectroscopic shift of two microsphere cavities. , 2003, Biophysical journal.

[13]  Andrea M Armani,et al.  Heavy water detection using ultra-high-Q microcavities. , 2006, Optics letters.

[14]  Brent E. Little,et al.  Acceleration sensor based on high-Q optical microsphere resonator and pedestal antiresonant reflecting waveguide coupler , 2001 .

[15]  Tobias Rossmann,et al.  Temperature sensitivity of silica micro-resonators , 2008 .

[16]  Tindaro Ioppolo,et al.  Micro-optical force sensor concept based on whispering gallery mode resonators. , 2008, Applied optics.

[17]  Tobias Rossmann,et al.  Whispering-gallery mode silica microsensors for cryogenic to room temperature measurement , 2010 .

[18]  S. Arnold,et al.  Whispering-gallery-mode biosensing: label-free detection down to single molecules , 2008, Nature Methods.

[19]  Larry R. Dalton,et al.  Polymer micro-ring filters and modulators , 2002 .

[20]  Rajan P Kulkarni,et al.  Label-Free, Single-Molecule Detection with Optical Microcavities , 2007, Science.

[21]  T. Rossmann,et al.  FABRICATION, CHARACTERIZATION AND MICROSENSING OF WHISPERING- GALLERY MODE MICRO-COUPLING SYSTEMS , 2008 .

[22]  Ignacio R. Matias,et al.  A fibre optic humidity sensor based on a long-period fibre grating coated with a thin film of SiO2 nanospheres , 2009 .

[23]  Zhixiong Guo,et al.  Simulation of single transparent molecule interaction with an optical microcavity , 2007 .

[24]  E. R. Thoen,et al.  Ultra-compact Si-SiO2 microring resonator optical channel dropping filters , 1998, IEEE Photonics Technology Letters.

[25]  L. Rayleigh,et al.  The theory of sound , 1894 .

[26]  Vladimir S. Ilchenko,et al.  CAVITY QED WITH HIGH-Q WHISPERING GALLERY MODES , 1998 .

[27]  Byoungho Lee,et al.  High resolution cryogenic optical fiber sensor system using erbium-doped fiber , 2001, Technical Digest. CLEO/Pacific Rim 2001. 4th Pacific Rim Conference on Lasers and Electro-Optics (Cat. No.01TH8557).

[28]  Vladimir S. Ilchenko,et al.  Quality-factor and nonlinear properties of optical Whispering-Gallery modes , 1989 .

[29]  S. Arnold,et al.  Shift of whispering-gallery modes in microspheres by protein adsorption. , 2003, Optics letters.

[30]  J. Bravo,et al.  Optical Fiber Humidity Sensors Using Nanostructured Coatings of SiO$_{2}$ Nanoparticles , 2008, IEEE Sensors Journal.

[31]  J P Korterik,et al.  Visualizing the whispering gallery modes in a cylindrical optical microcavity. , 1999, Optics letters.