A Cavity-SNOM (Scanning Near-field Optical Microscopy) Head Using a Laser Diode

Abstract
A cavity-SNOM (scanning near-field optical microscope) head using a laser diode is proposed and studied theoretically and experimentally. Theoretically, we study the optical properties using conventional rate equations. Several conditions to detect the SNOM signal with a photodiode are discussed. Experimentally, the dependence of output power of the laser diode on the injection current is measured. A sufficiently strong modulation signal is detected using a tapered fiber as the probe, but no modulation signal is detected using a tapered fiber with a small aperture (SNOM probe). The conditions for detecting a signal using a SNOM probe are also discussed, and we suggest that a laser diode with a SNOM probe fabricated on its facet is essential for realizing a practical cavity-SNOM head.