The invention relates to an optical device. The optical device comprises a waveguide core and a nanocomposite material optically coupled to the waveguide core. The nanocomposite material includes a plurality of quantum dots. The nanocomposite material has a nonlinear index of refraction γ that is at least 10 −9 cm 2 /W when irradiated with an activation light having a wavelength λ between approximately 3×10 −5 cm and 2×10 −4 cm.

Optical devices with engineered nonlinear nanocomposite materials

The invention relates to quantum dots, nanocomposite materials with quantum dots, optical devices with quantum dots, and related fabrication methods. In one embodiment, a quantum dot (104) comprises a core (106) including a semiconductor material Y selected from the group consisting of Si and Ge. The quantum dot also comprises a shell (108) surrounding the core. The quantum dot is substantially defect free such that the quantum dot exhibits photoluminescence with a quantum efficiency that is greater than 10 percent.

Quantum dots, nanocomposite materials with quantum dots, optical devices with quantum dots, and related fabrication methods

Cobalt–nickel oxide films of nominal 100 nm thickness, and resistivity on the order of 10−2 Ω cm have been deposited by spin casting from both aqueous and organic precursor solutions followed by annealing at 450 °C in air. Films deposited on sapphire substrates exhibit a refractive index of about 1.7 and are relatively transparent in the wavelength region from 0.6 to 10.0 μm. They are also magnetic. The electrical and spectroscopic properties of the oxides have been studied as a function of the x=Co/(Co+Ni) ratio. An increase in film resistivity was found upon substitution of other cations (Zn2+, Al3+,…) for Ni in the spinel structure. However, some improvement in the mechanical properties of the films resulted. A combination of x-ray diffraction, x-ray photoelectron spectroscopy, UV/Vis, and Raman spectroscopy indicated that NiCo2O4 is the primary conducting component and that the conductivity reaches a maximum at this stoichiometry. When x 0....

Synthesis and characterization of transparent conducting oxide cobalt–nickel spinel films

The nonlinear refraction coefficient of silica aerogel was estimated to be ∼−1.5×10−15 m2/W (∼−3.67×10−9 esu) with a signal-beam z-scan spectroscopy. The third-order nonlinear refraction coefficient of nanostructure silica aerogel was almost five orders larger than the nonlinear refraction (χ3) of bulk material. The large nonlinear refraction with high nonlinear figure of merit is an ideal optical property for nonlinear optical applications.

Large pure refractive nonlinearity of nanostructure silica aerogel

Integrated optics is the field which explores and develops methods and devices for the propagation and processing of optical signals in lightwave structures. One could think of switching or filtering of wavelengths, but also amplification or modulation of such optical signals. This thesis presents various methods, both theoretically as well as experimentally, to amplify, modulate or switch optical signals in an integrated optical circuit, without the intervention of slowing electronics.

All-optical Processes in Integrated Optical Devices Using Materials with Large Third-Order Nonlinearities and Gain

Nanocrystalline GaSb embedded in SiO2 film was grown by radio frequency co-sputtering. The nonlinear optical properties of the GaSb–SiO2 composite film have been studied at 632.8 nm by use of Z-scan technology. The appearance of a two photon absorption is predicted energetically above the exciton resonance for quantum-dot radii, which are between the electron and hole radii. The nonlinear refractive index of the GaSb–SiO2 composite film is positive. It shows that the GaSb–SiO2 composite film posses a large third-order nonlinear susceptibility about 7.84×10−9 esu. Room temperature transmission spectrum shows that the absorption edge exhibits a very large blue shift of 2.7 eV compared with that of bulk GaSb, which is mainly explained by the quantum confinement effect.

P Cheng

Papers

Enhancement of third-order nonlinearity of nanocrystalline GaSb embedded in silica film