The Archean Earth (3.8 to 2.5 billion years ago) was probably enshrouded by a photochemical haze composed of fractal aggregate hydrocarbon aerosols. The fractal structure of the aerosols would have had a strong effect on the radiative properties of the haze. In this study, a fractal aggregate haze was found to be optically thick in the ultraviolet wavelengths while remaining relatively transpar...

After a brief introduction to the basic concept of Free Electron Lasers operating in the Self-Amplified Spontaneous Emission (SASE) mode, the paper presents the rapid progress achieved during the past 3 years in successfully proving this FEL process at shorter and shorter wavelengths, meanwhile reaching 80 nm. The technical challenges are discussed to be overcome in building FEL facilities for ...

We demonstrate the operation of a cascaded continuous wave (CW) mode-locked Raman oscillator. The output pulses were compressed from 28 ps at 532 nm down to 6.5 ps at 559 nm (first Stokes) and 5.5 ps at 589 nm (second Stokes). The maximum output was 2.5 W at 559 nm and 1.4 W at 589 nm with slope efficiencies up to 52%. This technique allows simple and efficient generation of short-pulse radiati...

Abstract We document the evolution of north–south asymmetry (NSA) Titan’s haze albedo during Cassini mission between 2004 and 2017. analyze coadded cube images taken at 96 distinct wavelengths 0.35 1.05 μ m by Visual Infrared Mapping Spectrometer (VIMS-V) instrument from 14 Titan flybys. Over half a year, we observe near-complete transition in NSA boundary latitude across geographic equator sou...

It is generally assumed that correcting chromatic aberrations in imaging requires optical elements. Here, we show by allowing the phase image plane to be a free parameter, it possible correct variation of focal length over an extremely large bandwidth, from visible (Vis) longwave infrared (LWIR) wavelengths using single diffractive surface, i.e., flat lens. Specifically, designed, fabricated an...

We demonstrate second order optical nonlinearity in a silicon architecture through heterogeneous integration of single-crystalline gallium nitride (GaN) on silicon (100) substrates. By engineering GaN microrings for dual resonance around 1560 nm and 780 nm, we achieve efficient, tunable second harmonic generation at 780 nm. The χ2 nonlinear susceptibility is measured to be as high as 16 ± 7 pm/...

We probe turbulence structure from centimetric to metric scales by simultaneous imagery at mid-infrared and visible wavelengths at the VLT telescope and show that it departs significantly from the commonly used Kolmogorov model. The data can be fitted by the von Kármán model with an outer scale of the order of 30 m and we see clear signs of the phase structure function saturation across the 8-m...

This paper presents a method for detecting gallbladders attached to chicken livers using spectral imaging. Gallbladders can contaminate good livers, making them unfit for human consumption. A data set consisting of chicken livers with and without gallbladders, has been captured using 33 wavelengths within the visible spectrum. This work shows how to reduce the high number of wavelengths while m...