9:00 AM - 9:15 AM
[19a-S622-1] Observation of temperature dependence of passive THz near fields
Keywords:Near-field microscope,Terahertz,Thermal image
Recently, our group has developed a passive s-SNOM (scattering-type scanning near-field optical microscope) with an ultrahighly sensitive THz detector, called CSIP (charge-sensitive infrared phototransistor). The detection wavelength is λ = 14.1 ± 0.5 μm. The passive s-SNOM probes thermally excited electromagnetic evanescent field on metal and dielectric surfaces without using any external illumination or excitation. We have increased the SNR to 5.5 with 10 Hz scan rate as shown in Fig. (b) by improvement of optical components in the confocal microscope. To study the temperature dependence of passive near-field (NF) signals, we introduced a ceramic heater into the passive s-SNOM that can heat a sample to 100 °C. We demonstrate the temperature dependence of the thermally excited NF signals on Au. The NF signals increased by a factor of 3 when the temperature was elevated from 27 to 100 °C. The data can be fitted by a theoretical model. The result indicates that the sample is exposed to ambient radiation that may come from the optical components in the cryostat.