V. I. Bezborodov

260 GHz quasioptical setup for EPR and DNP experiments on the 9.2 Tesla DNP/NMR/EPR spectrometer

Transmission of microwave signals under low-losses conditions is highly demanding task in sub-mm EPR and DNP spectroscopy. We have designed and built a quasioptical setup in the Michelson interferometer configuration using oversized metallo-dielectric waveguides (MDW) of a square-shape cross-section and components such as attenuators, beam splitters, wavemeter, tapers to fundamental TE10 mode which have extremely low losses in sub-mm wave range. Following features of the setup such as total transmission losses below 2 dB from the source port to a resonator with a sample inside the cryomagnet; fine balance tuning between signal and reference channels affording up to 36 dB background signal suppression, linear-to-circular polarization conversion with a possibility to tune its phase, which allows effective suppression of reflected signal with respect to induction signal; switching between two microwave sources; and high power handling up to 20 Watt helped to reach high performance of the 9.2 Tesla DNP/NMR/EPR spectrometer. First liquid-state DNP results on nitroxide radicals in water will be presented.

Quasi-optical antenna duplexers

The development of antenna duplexers for transceiving quasi-optical systems of millimeter and submillimeter wavelengths are considered for two groups of devices — passive and active action. Duplexers, using properties of quasi-optical hybrids, belong to the first group, and duplexers on the base of semiconductor or ferrite devices are included to the second group. Results of developments and investigations of considered devices in the millimeter wave range are presented.

Quasioptical Polarization Attenuators in the Terahertz Frequency Range

The attenuator on the basis of a hollow metal-dielectric waveguide of square cross-section 10 x 10 mm with similar polarizing gratings has been realized and tested. The largest attenuation of such an attenuator in the range 0.26 THz is 35 dB, attenuation scale reading A=(0...25)dB, initial attenuation is 0.3dB, VSWR is less than 1.05. The attenuator error is plusmn(0.1+ 0.02A)dB.