Proposal of optical near-field probe using evanescent field of microdisk laser

We propose an active optical near-field probe constructed of a semiconductor microdisk laser and a monitor detector. When a microdisk is placed close to an object, the evanescent field of the whispering gallery mode in the microdisk is scattered and the lasing characteristic is modulated. It was theoretically shown that a probe, made by using a circular disk with a diameter almost equal to the lasing wavelength lambda and fixing the standing mode wave by a defect at the disk edge, shows a lateral resolution of 0.17 lambda x 0.23 lambda. Modulated light power by objects can be on the order of 100 mu W with a bias current of 1 mA, which is sufficient for high-contrast imaging. Cleavage and selective wet etching were investigated as fabrication methods of such probes that project over the substrate edge. High-speed microscopy will be realized through the use of a large-scale array integration of this probe.