We demonstrate a sum frequency generation (SFG) holographic imaging method by integrating the capabilities of holography and SFG spectroscopy. SFG can probe the molecular vibrational resonance in non-centrosymmetric media. Holographic recording can capture both the amplitude and the phase of the SFG signal, thus leading to label-free spectroscopic three-dimensional imaging.
We introduce a novel method for characterizing the spatio-temporal evolution of ultrashort optical field by recording
the spectral hologram of frequency resolved optical gating (FROG) trace. We show that FROG holography enables
the measurement of phase (up to an overall constant) and group delay of the pulse which cannot be measured by
conventional FROG method. To illustrate our method, we perform numerical simulation to generate holographic
collinear FROG (cFROG) trace of a chirped optical pulse and retrieve its complex profile at multiple locations as it
propagates through a hypothetical dispersive medium. Further, we experimentally demonstrate our method by
retrieving a 67 fs pulse at three axial locations in the vicinity of focus of an objective lens and compute its group
Two-Dimensional (2D) layered materials have garnered interest due to their novel optical and electronic properties. In
this work, we investigate Second Harmonic Generation (SHG) in Tungsten Disulfide (WS2) monolayers grown on
SiO2/Si substrates and suspended on a transmission electron microscopy grid; we find an unusually large second order
susceptibility, which is nearly three orders of magnitude larger than common nonlinear crystals. We have also developed
a Green’s function based formalism to model the harmonic generation from a 2D layer .
We perform numerical study of Compressive Multi-heterodyne Optical Spectroscopy [CMOS], which is based on multiple heterodyne measurements using a dynamically encoded frequency comb. Compressive sensing enables us to utilize sparsity in typical optical spectra of interest to reduce the number of heterodyne measurements. Numerical results are presented to demonstrate retrieval of coherent and incoherent sparse hypothetical Lorentzian spectra over a 42 nmwide bandwidth, sampled every 100 MHz (~0.2 pm), by using as few as 25% measurements.