Two-way interconversion of millimeter-wave and optical fields in Rydberg gases

We show that cold Rydberg gases enable an efficient six-wave mixing process where terahertz or microwave fields are coherently converted into optical fields and vice versa. This process is made possible by the long lifetime of Rydberg states, the strong coupling of millimeter waves to Rydberg transitions and by a quantum interference effect related to electromagnetically induced transparency (EIT). Our frequency conversion scheme applies to a broad spectrum of millimeter waves due to the abundance of transitions within the Rydberg manifold, and we discuss two possible implementations based on focussed terahertz beams and millimeter wave fields confined by a waveguide, respectively. We analyse a realistic example for the interconversion of terahertz and optical fields in rubidium atoms and find that the conversion efficiency can in principle exceed 90\%.Comment: 11 pages, 6 figures and supplementary informatio

Telecommunication applications of millimeter waves

For abstract see A81-4430

Imaging Polarimeter Arrays for Near-Millimeter Waves

An integrated-circuit antenna array has been developed that images both polarization and intensity. The array consists of a row of antennas that lean alternately left and right, creating two interlaced sub-arrays that respond to different polarizations. The arrays and the bismuth bolometer detectors are made by a photoresist shadowing technique that requires only one photolithographic mask. The array has measured polarization at a wavelength of 800 µm with an absolute accuracy of 0.8° and a relative precision of 7 arc min. and has demonstrated nearly diffraction-Iimited resolutiort of a 20° step in polarization

Polarization effects in millimeter wave propagation through rain: A review of present theory and a discussion of current experiments

An attempt was made to calculate the depolarization effects of rain on linearly or elliptically polarized millimeter waves. Results are given in graphs and tables

Optimal Constrained Wireless Emergency Network Antennae Placement

With increasing number of mobile devices, newly introduced smart devices, and the Internet of things (IoT) sensors, the current microwave frequency spectrum is getting rapidly congested. The obvious solution to this frequency spectrum congestion is to use millimeter wave spectrum ranging from 6 GHz to 300 GHz. With the use of millimeter waves, we can enjoy very high communication speeds and very low latency. But, this technology also introduces some challenges that we hardly faced before. The most important one among these challenges is the Line of Sight (LOS) requirement. In the emergent concept of smart cities, the wireless emergency network is set to use millimeter waves. We have worked on the problem of efficiently finding a line of sight for such wireless emergency network antennae in minimal time. We devised two algorithms, Sequential Line of Sight (SLOS) and Tiled Line of Sight (TLOS), both perform better than traditional algorithms in terms of execution time. The tiled line of sight algorithm reduces the time required for a single line of sight query from 200 ms for traditional algorithms to mere 1.7 ms on average

Thermal Excitation of Broadband and Long-range Surface Waves on SiO 2 Submicron Films

We detect thermally excited surfaces waves on a submicron SiO 2 layer, including Zenneck and guided modes in addition to Surface Phonon Polaritons. The measurements show the existence of these hybrid thermal-electromagnetic waves from near-(2.7 $\mu$m) to far-(11.2 $\mu$m) infrared. Their propagation distances reach values on the order of the millimeter, several orders of magnitude larger than on semi-infinite systems. These two features, spectral broadness and long range propagation, make these waves good candidates for near-field applications both in optics and thermics due to their dual nature.Comment: Applied Physics Letters, American Institute of Physics, 201

Novel and Efficient Hw-Sw Developments in Millimeter Wave Antenna Measurement Facilities

The aim of this communication is to show recent developments in the field of millimeter-wave antenna test ranges. Measurement facilities are complete systems used to acquire the radiated field by an antenna under test. When operating in millimeter waves, some common implementation principles become simply unaffordable. Manufacturing tolerances, structures computation times and available RF power offered by instrumentation become challenging aspects to cope with in millimeter waves. The developments shown in this paper focus on these issues

Spiral Density Waves in a Young Protoplanetary Disk

Gravitational forces are expected to excite spiral density waves in protoplanetary disks, disks of gas and dust orbiting young stars. However, previous observations that showed spiral structure were not able to probe disk midplanes, where most of the mass is concentrated and where planet formation takes place. Using the Atacama Large Millimeter/submillimeter Array we detected a pair of trailing symmetric spiral arms in the protoplanetary disk surrounding the young star Elias 2-27. The arms extend to the disk outer regions and can be traced down to the midplane. These millimeter-wave observations also reveal an emission gap closer to the star than the spiral arms. We argue that the observed spirals trace shocks of spiral density waves in the midplane of this young disk.Comment: This is our own version of the manuscript, the definitive version was published in Science (DOI: 10.1126/science.aaf8296) on September 30, 2016. Posted to the arxiv for non-commercial us

Design of Millimeter Wave Oscillator

Millimeter waves (mm-waves) are a spectrum frequency that ranges from 30 GHz until 300 GHz. Mm-waves is situated after microwaves and before infrared waves in frequency spectrum list. They also sometimes can be called as Extremely High Frequency (EHF). This group of frequency has wavelength (λ) between 1-mm until 10-mm scale. That is the reason why there are known as millimeter wave. Meanwhile, oscillator is an electronic circuit that can delivers repeated waveforms. Waveforms that deliver rely on upon how we plan the oscillator circuit. There are many applications of millimeter wave oscillator in our modern world nowadays. For example, this technology is widely used in communication, daily electronic gadgets, and also in military. Millimeter wave oscillators are the main segment that create electronic indicator to send the data through any type of medium, to the destination needed. Because of their important role in engineering technology, especially for telecommunications, it is very important for us to understand the operational principle and also designing the millimeter wave oscillator. Thus, by doing this project, hopefully we can understand more regarding this segment of spectrum. This task centers exclusively on the configuration of a millimeter parts and programming reenactment in direct schematic outline and additionally micro strip design. Negative conductance technique is utilized to plan a solid millimeter oscillator