Ultra stable tuning fork sensor for low-temperature near-field spectroscopy

Physics Department, Swiss Federal Institute of Technology Lausanne.
Ultramicroscopy (Impact Factor: 2.44). 03/2001; 90(2-3):97-101. DOI: 10.1016/S0304-3991(01)00144-9
Source: PubMed


We report on a distance control system for low-temperature scanning near-field optical microscopy, based on quartz tuning fork as shear force sensor. By means of a particular tuning fork-optical fiber configuration, the sensor is electrically dithered by an applied alternate voltage, without any supplementary driving piezo, as done so far. The sensitivity in the approach direction is 0.2nm, and quality factors up to 2850 have been reached. No electronic components are needed close to the sensor, allowing to employ it in a liquid He environment. The system is extremely compact and allows for several hours of stability at 5 K.

Download full-text


Available from: Benoit Deveaud, Oct 05, 2015
26 Reads
  • Source
    • "By bringing the tapered fibre probe into close proximity with the sample surface, the inevitable diffraction limit encountered in conventional far-field optical methods can be overcome. Since initial demonstrations that crystal quartz tuning forks can be used as sensors for acoustic (Güthner et al ., 1989) and force (Karrai & Grober, 1995) microscopy, applications of this technique have been extended to near-field optical microscopy (Davydov et al ., 1999; Crottini et al ., 2002), atomic force microscopy (Giessibl, 2000; Callaghan et al. , 2002), and electrostatic force microscopy (Seo et al ., 2002; Wang et al ., 2002). Recently, we demonstrated the working principles of the tapping-mode tuning fork near-field scanning optical microscopy (TMTF-NSOM; Tsai & Lu, 1998) and successfully applied this new method to study the physical properties of a single mode optical fibre waveguide (Tsai et al ., 1999), superresolution near-field structures (Tsai & Lin, 2000), and semiconductor lasers (Lu et al ., 2001). "
    [Show abstract] [Hide abstract]
    ABSTRACT: We present the implementation of a short-tip tapping-mode tuning fork near-field scanning optical microscope. Tapping frequency dependences of the piezoelectric signal amplitudes for a bare tuning fork fixed on the ceramic plate, a short-tip tapping-mode tuning fork scheme and an ordinary tapping-mode tuning fork configuration with an 80-cm optical fibre attached are demonstrated and compared. Our experimental results show that this new short-tip tapping-mode tuning fork scheme provides a stable and high Q factor at the tapping frequency of the tuning fork and will be very helpful when long optical fibre probes have to be used in an experiment. Both collection and excitation modes of short-tip tapping-mode tuning fork near-field scanning optical microscope are applied to study the near-field optical properties of a single-mode telecommunication optical fibre and a green InGaN/GaN multiquantum well light-emitting diode.
    Journal of Microscopy 04/2003; 209(Pt 3):205-8. DOI:10.1046/j.1365-2818.2003.01135.x · 2.33 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: V groove GaAs/AlGaAs quantum wires are investigated by spatially resolved photoluminescence spectroscopy using a low-temperature scanning near-field optical microscope. The spectra along the wires feature several sharp emission lines, which are understood as the emission from exciton states localized in inhomogeneities of the confining potential. It is expected that these exciton states spatially overlap and that their energies are correlated, which leads to level repulsion. The statistical analysis of the spectra in terms of autocorrelation functions clearly reveals this effect. In order to model photoluminescence rather than absorption spectra, we perform detailed simulations of exciton relaxation and luminescence kinetics in a disordered one-dimensional system, taking into account the realistic structure of the facets at the bottom of the V groove in our disorder model. Combining near-field measurements and numerical simulations we show that disorder prevents the full relaxation of excitons towards the local ground states in the dips of the disordered potential. As a consequence, luminescence from excited states is observed. We identify in the spatial and energy correlation between localized states the origin of the observed level repulsion and discuss the role played by the two facets at the bottom of the V groove in this mechanism. This analysis also highlights the relevance of the broad photoluminescence background observed in this and in analogous experiments. We propose as explanation for the origin of this broad background the strong exciton-acoustic phonon coupling that results in phonon sidebands in the spectrum of each localized state.
    Physical Review B 05/2004; 69(20). DOI:10.1103/PhysRevB.69.205321 · 3.74 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: We study exciton and biexciton spectra in disordered semiconductor quantum wires by means of nanophotoluminescence spectroscopy. We demonstrate a close link between the exciton localization length along the wire and the occurrence of a biexciton spectral line. The biexciton signature appears only if the corresponding exciton state extends over more than a few tens of nanometers. We also measure a nonmonotonous variation of the biexciton binding energy with decreasing exciton localization length. This behavior is quantitatively well reproduced by the solution of the single-band Schrödinger equation of the four-particle problem in a one-dimensional confining potential.
    Physical Review Letters 11/2005; 95(17):177404. DOI:10.1103/PhysRevLett.95.177404 · 7.51 Impact Factor
Show more