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—Recent changes in how people consume multimedia services are causing an explosive increase in mobile traffic. With more and more people using wireless networks, the demand for the ultra-fast wireless communications systems is increasing. To date, this demand has been accommodated with advanced modulation schemes and signal-processing technologies at… (More)
We demonstrate direct quadrature modulator and demodulator monolithic microwave integrated circuits for future terahertz communications at 300 GHz based on the quadrature phase-shift keying (QPSK) modulation format. For the modulating and demodulating signal, we employed half-Gilbert cell mixers, which provide balanced signaling and moderate performance in… (More)
In this paper, we present a microwave photonic technique to produce a noise signal from the microwave to sub-terahertz region with an optical amplified spontaneous emission noise, optical filter, and photodetector. With this scheme, it is easy to control the noise level by simply controlling the input optical noise power. In addition, the output noise… (More)
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We present a compact and stable terahertz (THz) vector spectroscopy system using silicon photonics technology. A silicon-based integrated phase control circuit greatly reduces the physical size of the continuous-wave THz spectroscopy system and enhances environmental phase stability. Differential lightwave phase control using two carrier-injection… (More)
For continuous millimeter and terahertz-wave applications, a two-mode optical signal generation technique that uses two arrayed waveguide gratings and two optical switch units is presented. In addition to easy and fast operation, this scheme offers broadband frequency tunability and high signal purity with a low spurious mode level. Mode spacing, which… (More)
A novel all-optical frequency up-converter utilizing four-wave mixing (FWM) in a semiconductor optical amplifier (SOA) was proposed and experimentally demonstrated. The frequency up-converter converted an optical intermediate frequency (IF) signal (f(IF) = 2.5 GHz) to an optical radio frequency (RF) signal (f(RF) = 35 and 40 GHz) through mixing with an… (More)