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We present a fully-integrated, fiber-coupled transceiver module for THz time domain spectroscopy. The transceiver combines emitter and receiver in a compact, 25 mm housing, which allows for THz reflection measurements under normal incidence. With a bandwidth of 4.5 THz and a peak dynamic range of 70 dB this THz reflection head is a versatile tool for material inspection and non-destructive testing.
Single-shot detection of a terahertz (THz) electric-field transient has been demonstrated using a high-bandwidth oscilloscope. The THz modulation was imprinted on a chirped picosecond probe pulse via an electro-optic crystal, and the probe pulse was subsequently temporally expanded to nanosecond time scales using the group velocity dispersion of a long optical fiber. The resulting GHz modulation on...
Research activity on development of gyrotron travelling-wave tubes (gyro-TWTs) at the Institute of Applied Physics of the Russian Academy of Sciences (IAP RAS) is presented. In the gyro-TWTs under discussion a helically corrugated waveguide is used as a principal part of their microwave circuits which ensures a number of advantages over other configurations of the gyro-TWTs.
We report on a detector-free on-chip dual frequency comb setup based on terahertz quantum cascade lasers. The presented dual-comb covers a bandwidth of 630 GHz with a centre frequency of 2.5 THz. Instead of a fast detector one of the lasers has been used as a fast detector itself. The frequency comb spacing was analysed using frequency counting techniques revealing an accuracy down to δfrep/fcarrier...
Two designs of fundamental mode rectangular to circular waveguide TE10 to TE11 mode converter are presented. The waveguide transitions are optimized for operation as an input coupler on a 372 GHz gyro-TWA for Dynamic Nuclear Polarization (DNP) enhancement of NMR imaging. A T-junction input coupler and a multiple hole directional coupler were optimized for operation between 360–384 GHz. The T-junction...
China Academy of Engineering Physics (CAEP) has been developing terahertz vacuum-electronic FWG-TWT amplifier for several years, and much progress has been achieved at 0.14THz, 0.22THz and 0.345THz. This paper presents 0.345THz FWG-TWT's theoretical analysis and 3-D PIC simulation results about electron gun with high area-compression ratio (≥ 25), high-field Periodic Permanent Magnet(≥ 0.45T), high...
In this paper, we present the performance of the first frequency multiplier using the non-linearity of distributed SIS junctions. The prototype doubler based on distributed SIS junction was for the first time able to pump an SIS mixer. The multiplication efficiency of the distributed SIS junction is 15–30 % for a fractional bandwidth of 10% with excellent spectral line purity. The measured −3 dB line...
Pumping a quadratic nonlinear crystal in the mid-IR we observe octave-spanning mid-IR supercontinua. A self-acting cascaded process leads to the formation of a self-defocusing nonlinearity, allowing formation of filament-free octave-spanning supercontinua in the 2.0–7.0 μm range with 10s of μJ pulse energies, much higher than filament-based techniques. This allows to use the supercontinuum as ultra-broadband...
An H-Band ×4 frequency multiplier chain implemented in an advanced 90 nm SiGe BiCMOS technology is presented. The chain achieves a peak output power of 4 dBm and consists of D-Band doubler followed by D-Band power amplifier which drives an H-Band doubler. It operates from 202 GHz to 247 GHz (3 dB power bandwidth) with 2 dBm input power at V-Band and consumes a total DC power of 250 mW. This paper...
An ultra-wide band W-Band travelling wave tube using staggered double vane slow wave structure (SDV-SWS) combined with plan alignment three pencil beams is investigated in this paper. Instead of only using the fundamental mode, the first two modes of SDV-SWS are designed to match with the same electron beam to promote the bandwidth. Particle in cell (PIC) simulations with our new type of two stages...
A novel multi-cavity extended interaction klystron (EIK) is designed as a coherent radiation source for THz science and technology application. The cavities adopt a composite structure with a double grating and sub-wavelength holes array structure. The high frequency characteristics of the structure are analyzed. The grating height and holes length have main influences on the frequency variation....
In order to get three-dimensional images with high resolution for the increasing demand of personnel screening, we need to develop wide-band holographic millimeter-wave imaging systems. For this purpose, an active submillimeter-wave imaging system based on vector network analyzer which utilizes a 280–320 GHz transceiver has been constructed and characterized. We tested the range and cross-range resolution...
A compact 272–288 GHz transmitter with integrated VCO is presented. This source is suitable for use in compact radar, imaging, and spectroscopy systems as an alternative to a W-band Gunn oscillator cascaded with W-band power amplifier and frequency multiplier. The transmitter has a x36 multiplication factor and has external dimensions of 0.875″ × 1.0″ × 1.25″. Measured output power is greater than...
This paper reports our progress of developing a 0.33-THz gyrotron which is based on a compact pulse magnet and can generate broadband coherent THz radiation with bandwidth exceeding 10 GHz and peak power about 2 kW. The design and fabrication of the key components are addressed in detail, including strong-field magnet, pre-bunched cavity, broadband Quasi-Optical mode converter, and Brewster window...
In this paper we report the first results of the optical components development and the overall optical design for a wideband receiver to simultaneously cover ALMA bands 2 and 3. Two types of feed horns and OMTs have been designed to couple to the ALMA telescope beam using a modified Fresnel lens. Both types of hardware have been manufactured and tested in a near field beam scanner. The measured beam...
By introducing side-absorbers to metal-metal waveguides of broadband terahertz quantum cascade lasers, we are able to control and completely suppress higher-order lateral waveguide modes. This change leads to an octave spanning laser spectrum with a 600 GHz wide flat top. In addition, the absence of higher order lateral modes has a strong effect on the pulse generation of injection seeded QCLs. We...
In this paper we present 1Gb/s wireless data reception at different sub-THz carrier wave frequencies, using a single quasi-optic Schottky receiver module. The module employs a Log-Spiral broadband antenna patterned on silicon. In this paper we present the performances at carrier wave frequencies ranging from 90 GHz to 330 GHz, demonstrating for the first time the flexibility of the module as versatile...
We report on a monolithic extracting structure for terahertz quantum cascade laser based frequency combs. For a spectral bandwidth of more than 600 GHz at a center frequency of 2.5 THz a frequency comb with well-defined farfield pattern could be achieved. In addition the dynamic range of the frequency comb has been significantly improved.
In feedhorn design, the power coupling to the fundamental free-space LG00 mode, or Gaussicity, is a good proxy for high performance, particularly the sidelobe and cross-polar levels and the near-field behavior. Gaussicity can be maximized by ensuring that the first few horn modes reach the aperture with the appropriate phase and amplitude relationship. We present two feedhorn designs for which the...
We present results of experimental study of the gain bandwidth (GBW) of MgB2 hot electron-bolometer (HEB) mixers at 0.1THz and 0.4THz. Antenna integrated 0.25–1.5um2 area devices were made from thin MgB2 films deposited with a custom made HPCVD system. Film as thin as 15–45nm had a Tc from 35K to 40K. The GBW was found to be independent on the bias conditions, the bath temperature, and the LO frequency...
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