Millimeter-wave dielectric properties of single-crystal ferroelectric and dielectric materials

Abstract

Transmittance measurements on various single crystal ferroelectric and dielectric materials, BaTiO(3), SrTiO(3), LiNbO(3), LiTaO(3), (PbMg(1/3)Nb(2/3)O(3))0.73-(PbTiO(3))0.27, LaAlO(3), and Bi(4)Ge(3)O(12), over a broad millimeter-wave (MMW) frequency range have been performed. Frequency dependence of the complex dielectric permittivity has been measured in the MMW region using high-power sources for the first time, using a free-space, quasi-optical MMW spectrometer equipped with high-power backward wave oscillators (BWOs) as sources of coherent radiation, tunable in the range from 30 to 120 and 180 to 260 GHz. These results are compared with MMW permittivity of these materials obtained by other methods as well as to RF, microwave, and optical frequency permittivities for all the materials tested. The effects of both crystallographic orientation and quality of the surface polishing of the crystals have been examined. Uncertainties and possible sources of instrumentation and measurement errors related to the freespace MMW technique are discussed. This work demonstrates that precise MMW permittivity data can be obtained even on relatively small and thin crystals of different surface conditions and orientations using the high-power BWO-based quasioptical approach.

Electro-Optic Coefficient of Thin-Film Lithium Niobate up to 270 GHz

“…Prior art regarding LN's material properties in the THz regime has focused on permittivity measurements. Reported values vary with material quality but generally indicate a constant value from 1 GHz up to optical phonon frequencies around a few THz [6]. The electro-optic coefficient is assumed to be constant up to these frequencies but its value has not been directly measured due to the dominating effects of RF attenuation in typical devices.…”

High gain circularly polarized slot‐coupled antenna for millimeter wave applications

“…The default value of the substrate permittivity stated in the datasheets is measured at 10 GHz. However, its variation at MMW frequencies “greater than 30 GHz” can be considered as a physical phenomenon reported in and documented by Roger Corp. in . The designed antenna, before mounting the horn, exhibits an impedance bandwidth of more than 1.4 GHz starts from 36 to 37.4 GHz.…”

Terahertz Time‐Domain Spectroscopy of 0.73Pb(Mg1/3Nb2/3)O3–0.27PbTiO3 Single Crystal

“…For PMN–PT single crystal, however, it is difficult to thin it to this level because of its poor mechanical strength. It is also important all the measurement methods involve multistep data treatments which inevitably could introduce some error . How to further improve the THz measurement accuracy is still in progress.…”

“…It is also important all the measurement methods involve multistep data treatments which inevitably could introduce some error. [26][27][28][29]35 How to further improve the THz measurement accuracy is still in progress.…”