Optical and Structural Properties of Carbon Nanotube-Rutile Heterostructures

The paper presents a study of the growth and characterization of carbon nanotube-rutile nanocomposites. The heterostructures were obtained with a chemical mixing method. Scanning electron microscope images show that the samples appear as a homogeneous powder of rutile with carbon nanotubes intercalated in interspaces between the TiO2 grains. Characterization by both X-ray photoelectron spectroscopy and cathodo-luminescence analysis show the formation of CO-Ti chemical bonds with a decrease of 0.8 eV in the band gap compared to pure rutile. The consequence of this band gap modification is a strong change in optical properties. Luminescence emission is drastically reduced and absorption in the visible range is increased of about 6% at very low concentration （1%） of carbon nanotubes.

A Polarization-Insensitive Broadband Metamaterial Absorber at the Optical Regime

We present a polarization-insensitive broadband absorber which has a feature of metal-insulator-metal structures. The top metal layer consists of four-fan-rings-shaped gold. Simulations show that the absorber exhibits an absorption of nearly unity at the wavelength of 386.1 nm and a relative absorption bandwidth of 0.548, which refers to the ratio of the full absorption bandwidth over an absorption of 0.9 to the central wavelength. Meanwhile, the absorption is nearly independent of the polarized direction of the incident wave. This absorption bandwidth with insensitive polarization is widely reported to date for such metal-insulator-metal structures. Such a structure offers a way of realization of a polarization-insensitive broadband absorber ranging in ultraviolet-to-visible wavelengths.

OPTICAL MEA SUREMENTS OF RAT MUSCLE SAMPLES UND ER TREATMENT WITH ETHYLENE GLYCOL AND GLUCOSE

With the objective to study the variation of optical properties of rat muscle during optical clearing,we have performed a set of optical measurements from that kind of tissue.The.measurements performed were total tr ansmittance,ollimated transmit tance,specular reflec-tance and total reflectance.This set of measurements is suficient to determine diffuse reflectance and absorbance of the sample,also necessary to est imate the optical properties.All the per formed measurements and calculated quantities will be used later in inverse Monte Carlo(IMC)simu-lations to determine the evolution of the optical properties of muscle during treatments with ethylene glycol and glucose.The results obt ained with the measurements already provide some information about the optical c learing treatments applied to the muscle and translate the mechanisms of turning the tissue more transparent and sequence of regimes of optical clearing.

Antimonene-based saturable absorber for a soliton mode-locked and Q-switched fiber laser in the 2 μm wavelength region

We demonstrate antimonene as a saturable absorber(SA) to generate an ultrafast mode-locked and Q-switched laser in the 2 μm wavelength region. The two antimonene-based SAs were prepared and inserted separately in a thulium–holmiumdoped fiber laser to produce the pulsed laser. Antimonene was coated onto a tapered fiber to generate soliton mode-locked pulses and used in thin-film form for the generation of Q-switched pulses. The mode-locking was stable within a pump power of 267 m W–511 m W, and the laser operated at a central wavelength of 1897.4 nm. The mode-locked laser had a pulse width of 1.3 ps and a repetition rate of 12.6 MHz, with a signal-to-noise ratio of 64 d B. Q-switched laser operation was stable at a wavelength of 1890.1 nm within a pump power of 312 m W–381 m W. With the increase in pump power from 312 m W to 381 m W, the repetition rate increased to a maximum of 56.63 k Hz and the pulse width decreased to a minimum value of 2.85 μs. Wide-range tunability of the Q-switched laser was also realized within the wavelength range of1882 nm–1936 nm.

Model of Raman–Nath acousto-optic diffraction

In this Letter, we discuss Raman–Nath acousto-optic diffraction, and a new model of Raman–Nath acousto-optic diffraction is presented. The model is based on the individual and simultaneous occurrences of phase-grating diffraction and the Doppler effect and optical phase modulation and photon–phonon scattering. We find that the optical phase modulation can cause temporal and spatial fluctuations of the diffracted light power escaping from the acoustic field.

Background-Free Optical Sampling System Using Si Avalanche Photodiode as Two-Photon Absorber

The introduction of a double-chopping scheme eliminates the background level in the optical sampling system, where a Si avalanche photodiode acts as a two-photon absorber. We successfully demonstrate background-free optical sampling of 40-GHz and 160-GHz pulse trains.