Presentation on theme: "Limits and Interfaces in Sciences / Kumboldt-Kolleg São Paulo-SP,"— Presentation transcript:
Limits and Interfaces in Sciences / Kumboldt-Kolleg São Paulo-SP, 28 th - 30 th October 2009
1.Introduction 2.Scanning near-field optical microscope (SNOM) probe for controlling Raman microlaser action 3.SNOM probe as a tool for controlling the interaction of a nanoscopic light emitter with confined electromagnetic field Motivation Using scanning probe tech- niques (SNOM) for controlling and manipulating confined light in microresonators, as well as to control the interaction of single nanoparticles with it.
St. Paul´s cathedral, London Lord Rayleigh, m 15 µm Easily produced by melting an optical fiber with a CO 2 laser. Diameters from 20 m to 200 m. Q factors up to May store photons for some s. Comparison: tuning fork 550 Hz, same Q: oscillates for 4 days!!! Modal volume V~300 3 Evanescent field allows the external coupling. Braginsky et al., Phys. Lett. A 137, 393 (1989); L. Collot et al., Eur. Phys. Lett. 23, 327 (1993). Light is trapped in a whispering gallery mode by successive total internal reflections, travel- ling in a great circle along the cavity's perimeter. Microspheres as optical cavities 100 m Represent optical resonators with ultra-high Q-factors and small mode volumes. ~33 m
Spectroscopy of the microspheres´ eigenmodes Typical spectrum measured by absorption and scattering
Constant distance (~10 nm) between the microsphere sur- face and the SNOM tip via a shear force control loop. Tip-limited (~50 nm) optical resolution. Allows getting a topogra- phical image. Scanning Near-field Optical Microscopy 20mm
For Q = 10 9, P threshold = 4.3 W world record! =70 m Q=3 10 8 =795nm 4 mm
Pump mode 795 nm) Laser mode 814 nm) Tip reduces the Q-factor of the WGM laser threshold increases A. Mazzei et al., Appl. Phys. Lett. 89, (2006).
Fluorescence microscope images of a single 200 nm dye-doped bead attached to a SNOM tip Without notch filter With notch filter
200 nm 200 nm in diameter dye-doped bead S. Götzinger et al., Nano Lett. 6, 1151 (2006).
via scope via prism S. Götzinger et al., J. Opt. B: Quantum Semiclass. Opt. 6, 154 (2004). Coupling of single semiconductor quantum dots:
Multimode fiber connected to PMT PrismCollimating lens Monomode fiber socket Rotation stage Monomode fiber with collimating and focus- sing lenses Goniometer Confocal microscope obejctive Temperature stabilized Cu block Stabilized 3D piezo stack Cu tube with microsphere
Cavity-mediated photon transfer Intensity (arb. units) Wavelength (nm) Intensity (arb. units) Wavelength (nm) S. Götzinger et al., Nano Lett. 6, 1151 (2006). Our calculations show that the transfer efficiency is 10 6 times larger that in free space! exc =532nm =35 m
By using our setup, we have obtained cavity-mediated enhanced pho- ton transfer between two single nanoparticles. We have used silica microspheres to observe an ultralow threshold Raman microlaser action and used a SNOM probe to control it. We have shown how to fabricate microresonators presenting resonan- ces with ultrahigh quality factors, i.e., ultralong photon storage times. Thank you for your attention!!! And pretty close to our labs... Baía dos Porcos, Fernando de Noronha-PE A single nanoparticle was attached to the end of a near-field probe. The coupling to a high-Q WGM was obtained in a very controlled way.