Ultrafast Optical Technology Research Articles

Review of photomixing continuous-wave terahertz systems and current application trends in terahertz domain

Within the last two decades, terahertz systems have become a well-established tool in scientific laboratories and industrial research and development departments. Unlike the methods of pulsed terahertz radiation that mainly rely on ultrafast optical technology, the technology behind continuous-wave terahertz sources and detectors has a long history involving many different types of technical schemes. The intent is to provide a brief review of the continuous-wave terahertz systems that are based on photomixing and current application trends in the field of terahertz technology.

Single nanowire optical correlator.

Integration of miniaturized elements has been a major driving force behind modern photonics. Nanowires have emerged as potential building blocks for compact photonic circuits and devices in nanophotonics. We demonstrate here a single nanowire optical correlator (SNOC) for ultrafast pulse characterization based on imaging of the second harmonic (SH) generated from a cadmium sulfide (CdS) nanowire by counterpropagating guided pulses. The SH spatial image can be readily converted to the temporal profile of the pulses, and only an overall pulse energy of 8 μJ is needed to acquire a clear image of 200 fs pulses. Such a correlator should be easily incorporated into a photonic circuit for future use of on-chip ultrafast optical technology.

Ultrafast technology in telecommunications

Ultrafast optical technologies have produced pulses as short as 4.5 fs, and optical pulses continue to get shorter and shorter. But, in the meantime, telecommunications has continued to evolve to higher and higher bit rates and capacities. Most recently, optical data has been transmitted at 1.28 Tb/s over a distance of 70 km, leaving only 800 fs between the bits, and ultrafast optical sources have been demonstrated in novel WDM systems as well. We review some of the fundamental features of ultrashort optical pulses, and discuss what impact it has had and may have in the future of telecommunications. This paper is intended to be a high-level view and is based on a recent invited talk.