[Audio] ECE 616: Ultrafast Optics

Related reading: Ultrafast Optics, 9.6.

Related reading: Ultrafast Optics, 9.1-9.3.

Related reading: Ultrafast Optics 8.1

Common ultrafast laser pulse characterization methods, such as autocorrelation, frequency-resolved optical gating (FROG), and spectral phase interferometry for direct electric-field reconstruction (SPIDER), can only measure the pulse characteristics, whose use is limited when measuring and shaping the pulse are both required. As a pulse-shaper-assisted measurement method, multiphoton intrapulse interference phase scan (MIIPS) can simultaneously characterize the pulse and shape it into specified forms. In MIIPS, a pulse shaper imposes a known reference spectral phase function to the pulse to locally cancel distortions caused by the spectral phase to be determined. The effect of the introduced phase function is monitored through measuring the spectrum of a nonlinear signal of the pulse. When the desired cancellation is achieved, the unknown spectral phase function can be deduced from the reference function. In this study, the theory of MIIPS is analyzed and the experimental realization is discussed.

Related reading: Ultrafast Optics, 8.4.

Related reading: Ultrafast Optics, 7.5.

Related reading: Ultrafast Optics, 7.1.

Plasmonics has gained significant attention in the recent days owing to its capability of providing sub-wavelength confinement of light. As a consequence of sub-wavelength confinement of electric field, the field intensity issignificantly enhanced. High field intensity achieved by plasmonics, together with high intensity provided by ultrafast pulse excitation techniques,provide an efficient way to harness the non-linearity of many materials. Non-linear characteristics of plasmonic devices can enable important applications such as plasmonic switches. Owing to the technological importance of these applications, active/non-linear plasmonics is gaining greater attention in the past few years. This review focuses on a few recent reports where plasmonic structures have been used to demonstrate various effects such as efficient four-wave mixing, ultrafast switching and magneto-plasmonic microinterferometry.

Dual comb spectroscopy is introduced, a technique that is basedon the beating of two frequency combs. A sample is first interrogated bythe combs before they are beat together via photodiode which down convertsthe signal from the optical to RF domain where it can be processed with electronics. A overview of the concept is given as well as a brief look intocurrent achievements and limitations.

Related reading: Ultrafast Optics, 8.3.