<para xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> The National Institute of Information and Communications Technology (NICT, Japan) started the Terahertz Project in April 2006. Its fundamental purpose next five years is to enable a nationwide technical infrastructure be created for diverse applications terahertz technology. includes development semiconductor devices such as quantum cascade lasers, terahertz-range well photodetectors,...

Building receivers (RXs) that operate above the transistor unity-power-gain frequency, f <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">max</inf> , is extremely challenging because an LNA-less architecture must be adopted. This paper reports on a 300-GHz CMOS RX operating NMOS /max. Its conversion gain, noise figure, and 3-dB bandwidth are, respectively, −19.5 dB, 27 26.5 GHz. The achieved wireless data rate of 32 Gb/s with 16QAM. It shows...

The demand for high-speed and highly efficient optical communication techniques has been rapidly growing due to the ever-increasing volume of data traffic. As well as digital coherent used core metro networks, intensity modulation direct detection (IM-DD) are still promising schemes in intra/inter centers thanks their low latency, high reliability, good cost performance. In this work, we study a microresonator-based frequency comb potential light source future IM-DD systems where...

We have directly determined the spectral shape of complex conductivities Bloch oscillating electrons by using time-domain terahertz (THz) electro-optic sampling technique, and presented experimental evidence for a dispersive gain in superlattices. This unique without population inversion arises from nonclassical nature oscillations; that is, phase oscillation is shifted $\ensuremath{\pi}/2$ semiclassical charged harmonic when driven same ac field. By increasing bias electric field, bandwidth...

We have calculated the performance of a recently proposed four-level scheme terahertz quantum cascade laser (4L terahertz-QCL) with nonequilibrium Green’s function method. The calculation result for 40 K showed that 4L QCL has larger gain than conventional resonant phonon QCL. This is because large number electrons accumulate in upper lasing level and contribute to new scheme. When temperature increased, advantage decreases due thermally activated scattering.

The authors tried real-time imaging of THz radiation from Quantum Cascade Laser (QCL), using vanadium oxide (VOx) microbolometer focal plane arrays (FPAs) 320x240 with pitches 37 μm and 23.5 as well 640x480 23.5μm pitch. QCL has such parameters 3.1 emission frequency (97μm in wavelength), 300-400 nsec pulse width, 1.07 msec repetition period, 30 mW peak intensity, 15K operation temperature. is collimated by off-axis parabola (OAP) focused on FPA another OAP. 10 range infrared scene blocked...

In this study, W-band (75–110 GHz) antenna-coupled optical modulators with a cyclo-olefin polymer (COP) lower cladding, an electro-optic (EO) waveguide, and gap-embedded patch antenna array were fabricated using transfer bonding method of poled EO film. A carrier-to-sideband ratio (CSR) 56 dB corresponding to phase shift 3 mrad was obtained under irradiation 100 GHz electromagnetic waves power 12.8 W/m 2 . Our devices have the potential achieve highly efficient wireless–optical signal...

Uncooled Terahertz (THz) focal plane array (FPA), 320x240 format-23.5 μm pitch, and THz imager were developed. There are two types of THz-FPAs, i.e., broad-band type narrow-band type. Since THz-FPA was developed, a couple modifications have been made to improve Noise Equivalent Power. The has such new structure that Si cover is put above thermal isolation at distance half wavelength interest. Measurements on responsivities FPAs show enhancement by factor ca. 3. Lock-in imaging technique...

All-optical tunable buffering was recently achieved on a chip by using dynamically tuned coupled mode induced transparency, which is an optical analogue of electromagnetically transparency. However, the small Q s about 105 used in those systems were limiting maximum time to few hundred ps. Although employing ultra-high whispering gallery (WGM) microcavity can significantly improve time, dynamic tuning WGM has remained challenging because thermo-optic and pressure tunings, are widely for...

Fiber-wireless transmission in the terahertz-wave band as well millimeter-wave is key for a seamless integration of radio and optical networks physical layer. Advanced fiber communication technology enables high precision direct waveform transfer between domains. For realization conversion, an optical-terahertz converter configured with heterodyning optical-to-terahertz conversion. Analog modulation techniques by input signal intermediate frequency component after downconversion are utilized...

The vast terahertz frequency band around 300 GHz has a potential to be used for next-generation wireless communication. 300-GHz transceiver been developed using silicon CMOS technology of which the unity-power-gain frequency, $\pmb{f_{\max}}$, is below said band. Possible channel allocation and design are discussed.

In this study, photonics-based near-field measurement and far-field characterization in a 300-GHz band are demonstrated using an electrooptic (EO) sensor with planar scanning. The field to be measured is up-converted the optical domain (1550 nm) at EO delivered system fiber. typical phase drift of 0.46° for one-dimensional time 13 s, which smaller than standard deviation 1.2° scale. patterns horn antenna calculated from distribution compared that direct vector network analyzer. For angular...

We have demonstrated the phase-locking of a THz quantum cascade laser (THz-QCL) toward realization an accurate and stable local oscillator for high-resolution receiver. The beat note between THz-QCL reference was obtained by heterodyne mixing in superconducting hot electron bolometer mixer (HEBM) used stabilizing phase 3.1 radiation from THz-QCL. phase-locked fully evaluated with superlattice harmonic operating band, this revealed that synchronized microwave fractional frequency instability...

A short-range terahertz (THz) wireless transmission in the 300 GHz band is demonstrated using low-profile wavelength-scaled dielectric transmitting and receiving cuboid antennas (DCAs). These are made of polytetrafluoroethylene with dimensions approximately 1.2 mm × 1.3 mm. The near-field pattern a DCA at was measured an electro-optic sensing technique, its far-field characterization based on to transformation. antenna gain 15.06 ± 0.06 dBi. By employing DCAs as antennas, 17.5 Gbps data rate...

This Letter demonstrates a high-speed fiber-terahertz-fiber system in the 355-GHz band using stable optical frequency comb generation and photonics-enabled receiver. At transmitter, single dual-drive Mach-Zehnder modulator is employed to generate by driving under an optimal condition. antenna site, receiver consisting of local oscillator signal generator, doubler, electronic mixer used downconvert terahertz-wave microwave band. Simple intensity modulation direct detection method are for...

We have demonstrated terahertz (THz) wireless transmission of quadrature phase-shift keying (QPSK) signals at 2 and 3 THz-bands. Despite higher atmospheric attenuation frequencies above 1 THz, it might be applicable for short-range communications. The proposed system is composed a photonics-based transmitter using an optical comb source heterodyne receiver hot electron bolometer mixer (HEBM). In the transmitter, THz are generated by photomixing carriers extracted from broadband combs....

A terahertz-wave communication system directly connected to an optical fiber network is promising for application future mobile backhaul and fronthaul links. The possible broad bandwidth in the terahertz band useful high-speed signal transmission as well radio-space encapsulation high-frequency carrier. In both cases, low-latency feature becomes important enhance throughput realized by waveform transport technology without any digital-signal-processing-based media conversion. highly precise...

We have investigated dephasing mechanisms of Bloch oscillating electrons in GaAs-based superlattices (SLs) by time-domain terahertz electro-optic sampling method. It was found that time τr for GaAs∕AlAs SLs the Wannier-Stark regime rapidly becomes shorter with decreasing well width Lw as τr∝Lw3−5. The observed strong dependence indicates dominant mechanism is interface roughness scattering, which indeed confirmed quantitative comparison between theory and experiment. also alloy disorder...

We have developed the 3.1-THz heterodyne receiver using an NbTiN Hot-Electron Bolometer (HEB) mixer and a THz Quantum Cascade Laser (THz-QCL) as local oscillator. A quasi optical twin-slot antenna is adopted for coupling of RF signal with mixer. The noise temperature measured to be 5600 K in DSB. When loss corrected, it low 2100 K. This result demonstrates that HEB works equivalent level performance at 3.1 comparison NbN mixers usually employed this frequency region.

A 300-GHz CMOS receiver module with a WR-3.4 waveguide interface is presented. The flip-chip mounted on low-cost multilayered glass epoxy printed circuit board (PCB). transmission-line-to-waveguide transition back-short structure built into the PCB. measured conversion gain, noise figure, and 3-dB bandwidth of are approximately −23.7 dB, 33 dB 18.4 GHz, respectively. Packaging loss estimated to be 4 from gain chip −19.5 dB. wireless data rate 20 Gbit/s 16-QAM was achieved using designed modules.