Transient-grating single-shot supercontinuum spectral interferometry (TG-SSSI)

Simplified single-shot supercontinuum spectral interferometry

We have experimentally demonstrated a simplified method for performing single-shot supercontinuum spectral interferometry (SSSI) that does not require pre-characterization of the probe pulse. The method, originally proposed by D. T. Vu, D. Jang, and K. Y. Kim, uses a genetic algorithm (GA) and as few as two time-delayed pump-probe shots to retrieve the pump-induced phase shift on the probe [Opt. Express 26, 20572 (2018)]. We show that the GA is able to successfully retrieve the transient modulations on the probe, and that the error in the retrieved modulation decreases dramatically with the nu…

Simplified Chirp Characterization in Single-shot Supercontinuum Spectral Interferometry

Single-shot supercontinuum spectral interferometry (SSSI) is an optical technique that can measure ultrafast transients in the complex index of refraction. This method uses chirped supercontinuum reference/probe pulses that need to be pre-characterized prior to use. Conventionally, the spectral phase (or chirp) of those pulses can be determined from a series of phase or spectral measurements taken at various time delays with respect to a pump-induced modulation. Here we propose a novel method to simplify this process and characterize reference/probe pulses up to the third order dispersion from…

Supercontinuum generation in silicon Bragg grating waveguide

Supercontinuum generation is an extensively studied and arguably the most important and all-encompassing nonlinear phenomenon. Yet, we do not have a good control over all the signals generated in this process. Usually a large part of an octave spanning spectrum has orders of magnitude too much weaker signal than the peak to be useful for any application. In this work we show strong signal generation within a supercontinuum using a silicon Bragg grating waveguide. We show up to 23 dB of signal enhancement over a 10 nm full-width-at-half-maximum bandwidth at the Bragg resonance in the telecom wi…

Free-space propagation of spatio-temporal optical vortices (STOVs)

Spatio-temporal optical vortices (STOVs) are a new type of optical orbital angular momentum (OAM) with optical phase circulation in space-time. In prior work [N. Jhajj et al., Phys. Rev X 6, 031037 (2016)], we demonstrated that a STOV is a universal structure emerging from the arrest of self-focusing collapse leading to nonlinear self-guiding in material media. Here, we demonstrate linear generation and propagation in free space of STOV-carrying pulses. Our measurements and simulations demonstrate STOV mediation of space-time energy flow within the pulse and conservation of OAM in space-time. …

用于视网膜成像的散粒噪声极限、10 MHz扫频源光学相干断层扫描

Shot-noise limited, 10 MHz swept-source optical coherence tomography for retinal imaging

本文提出一种基于全正常色散超连续谱和长啁啾光纤布拉格光栅的10 MHz低噪声扫频源，在1050 nm附近实现90 nm调谐，视网膜成像灵敏度达84 dB并接近散粒噪声极限。

Gigahertz Self-referenceable Frequency Comb from a Semiconductor Disk Laser

We present a 1.75-GHz self-referenceable frequency comb from a vertical external-cavity surface-emitting laser (VECSEL) passively modelocked with a semiconductor saturable absorber mirror (SESAM). The VECSEL delivers 231-fs pulses with an average power of 100 mW and is optimized for stable and reliable operation. The optical spectrum was centered around 1038 nm and nearly transform-limited with a full width half maximum (FWHM) bandwidth of 5.5 nm. The pulses were first amplified to an average power of 5.5 W using a backward-pumped Yb-doped double-clad large mode area (LMA) fiber and then compr…