For interstellar missions, directed energy is envisioned to drive wafer-scale spacecraft to relativistic speeds. Spacecraft propulsion is provided by a large array of phase-locked lasers, either in Earth orbit or stationed on the ground. The directed-energy beam is focused on the spacecraft, which includes a reflective sail that propels the craft by reflecting the beam. Fluctuations and asymmet...

We demonstrate a simple optical clock based on an optical transition of iodine molecules, providing a frequency stability superior to most rf sources. Combined with a femtosecond-laser-based optical comb to provide the phase coherent clock mechanism linking the optical and microwave spectra, we derive an rf clock signal of comparable stability over an extended period. Measurements suggest the s...

Laser action has been demonstrated in chalcogenide glass microsphere. A sub millimeter neodymium-doped gallium lanthanum sulphide glass sphere was pumped at 808 nm with a laser diode and single and multimode laser action demonstrated at wavelengths between 1075 and 1086 nm. The gallium lanthanum sulphide family of glass offer higher thermal stability compared to other chalcogenide glasses, and ...

The behavior of a semiconductor laser subject to filtered optical feedback is studied in dependence on the width of the filter. Of special interest are pure frequency oscillations where the laser intensity is practically constant. We show that frequency oscillations are stable in a large region of intermediate values of the filter width, where the dispersion of the filter is able to compensate ...

background: the dispersed phase volume fraction plays key role in oil-in-water emulsion stability by different mechanisms like partial flocculation, depletion flocculation and bridging flocculation. since the mentioned mechanism is affected by emulsifier concentration presented in system, the major aim of this study was to investigate the effect of dispersed phase volume fraction on physical st...

− We demonstrate an ultra-stable visible laser source that can be generated from injection locked infrared DFB based on optical comb. The optical comb was used as injection source and locked to an acetylene stabilization laser as a reference source of optical communication region. The DFB laser was selectively injection locked from only one among the comb mode with 25 GHz spacing. The ultra-sta...

graphene oxide was prepared using modified hummers method. stable ethylene-glycol nanofluids containing graphene oxide nanosheets were provided. nd: yag pulsed laser was applied to prepare reduced nanofluids. experimental results revealed that thermal conductivity of the nanofluids is increased with increasing the concentration of graphene oxide (go) in ethylene glycol. the enhancement ratio of...

We report a precision and fast wavelength tuning technique demonstrated for a digital-supermode distributed Bragg reflector laser. The laser was dynamically offset-locked to a frequency-stabilized master laser using an optical phase-locked loop, enabling precision fast tuning to and from any frequencies within a ~40-GHz tuning range. The offset frequency noise was suppressed to the statically o...

The master laser is changed to ECDL (extended-cavity diode laser) from DBR (Distributed Bragg reflector) diode laser [1]. The frequency of ECDL is locked to the crossover resonance between F=4 to F'=4 and F=4 to F'=5 transitions using the FM spectroscopy. In order to generate an optical pump (F=4 to F'=4) and a probe light (F=4 to F'=5), two acousto-optic modulators are used. The laser beams ar...

Graphene oxide was prepared using modified Hummers method. Stable ethylene-glycol nanofluids containing graphene oxide nanosheets were provided. Nd: YAG pulsed laser was applied to prepare reduced nanofluids. Experimental results revealed that thermal conductivity of the nanofluids is increased with increasing the concentration of graphene oxide (GO) in ethylene glycol. The enhancement ratio of...