We demonstrate the phase locking of a 2.7 THz metal-metal waveguide quantum cascade laser (QCL) to an external microwave signal. The reference is the 15th harmonic, generated by a semiconductor superlattice nonlinear device, of a signal at 182 GHz, which itself is generated by a multiplier chain (x12) from a microwave synthesizer at approximately 15 GHz. Both laser and reference radiations are ...

Microwave circuits are indispensable for mobile and multimedia communication. However, these circuits are very difficult to design, because of the nature of distributed-constant circuits in the microwave range (i.e., over 1 GHz). These circuits are also difficult to adjust for optimum performance, even for experienced engineers. These related problems make development costs of microwave circuit...

High-repetition-rate optical frequency combs can act as broadband photonic mixers and downconvert a microwave signal to an intermediate frequency (IF) band so that it becomes accessible with high-speed electronics. In this Letter, we show that with line-by-line pulse shaping and dispersive propagation, the photonic mixer can simultaneously perform programmable multitap complex-coefficient-filte...

An analysis is presented for the conversion loss and noise of microwave and millimeter-wave mixers. The analysis includes the effects of nonlinear capacitance, arbitrary embedding impedances, nonideality of microwave diodes, and shot, thermal, and scattering noise generated in the diode. Correlation of downconvertd components of the time-varying shot noise is shown to explain the “anomalous” no...

We describe and demonstrate experimentally a method for photonic mixing of microwave signals by using a silicon electro-optical Mach-Zehnder modulator enhanced via slow-light propagation. Slow light with a group index of ~11, achieved in a one-dimensional periodic structure, is exploited to improve the upconversion performance of an input frequency signal from 1 to 10.25 GHz. A minimum transmis...

We have measured the spectral linewidths of three continuous-wave quantum cascade lasers operating at terahertz frequencies by heterodyning the free-running quantum cascade laser with two far-infrared gas lasers. Beat notes are detected with a GaAs diode mixer and a microwave spectrum analyzer, permitting very precise frequency measurements and giving instantaneous linewidths of less than -30 k...

We are developing a low noise heterodyne receiver at 3THz band for applications of atmospheric and astronomical research and for application of wireless communications. We have developed a phase-locking system of a terahertz quantum cascade laser (THz-QCL) by using a hot electron bolometer mixer. The THz-QCL was locked to terahertz reference generated by an optical frequency comb and a photo mi...

A radar transceiver operating at 1.56 THz has recently been developed to obtain coherent, fully polarimetric W-band (98 GHz) RCS images of 1:16 scale model targets. The associated optical system operates by scanning a small focused beam of sweptfrequency radiation across a scale model target to resolve individual scattering centers and obtain the scaled RCS values for the centers. Output from a...