Presentation on theme: "Fabrication of whispering gallery modes microcavity during optical trapping ASHIDA LAB TOYOTA YUSUKE."— Presentation transcript:
Fabrication of whispering gallery modes microcavity during optical trapping ASHIDA LAB TOYOTA YUSUKE
Contents Introduction ・ optical cavity ・ whispering gallery modes (WGM) microcavity Motivation Radiation force Experimental method & set up Result Future plan
Optical cavity d 2d = n λ resonate application ・ laser ・ increase of non-linear optical effect ・ light amplifier vacuum
Q-factor & mode volume Q = τ ν τ : photon lifetime in cavity ν : resonance frequency d loss mode volume the smaller mode volume become, the more light reflect. low Q-factor many losses
WGM Microcavity High Q-factor despite small mode volume Wave optics LASER Wave LASER Geometric Geometric optics
Mode number n, m, l Mode number n, m, l For example A variety of mode numbers make a variety of mode patterns. Fundamental WGM n n = 1 Kippenberg, T.J.A. Nonlinear optics in ultra-high-Q whispering-gallery optical microcavities. (2004). at
l Mode number l l = 4 l = 3 half wavelength
m Mode number m m = 0 m = l － 2 m = l m = 0 m = l － 2 m = l
Free spectra range Wavelength Oblate sphere sphere l = 2 l = 3 l = 4 l = 2 l = 3 l = 4 intensity
Previous work sample Ablation laser Laser ablation in superfluid HeMelting of optical fiber CO2 laser Optical fiber 2 K Fabricate Multiple microcavities at one time Impossible to select size Oblate sphere Limited material Possible to select size
Motivation Size selectivity, high sphericity, a variety of material Optical trap trap beam CO2 laser surface tensionHow to form sphere ??
Radiation force Gradient force Dissipative force Optical manipulation Optical trap
Experimental method Dual beam trap Gradient force Optical trap Dissipative force d important important d d is longer than that of single beam trap.
Optical trap Optically trapped single SiO2 microsphere
Set up Ti:sapphire laser 784 nm, 1.8 W CO2 laser 10.6 μm Polarized BS L1 L2 CF White light spectrometer λ/2 L1 White light spectrometer 90° L1 f = 8.00 mm NA = 0.5 L2 f = 100 mm