Study on the colloidal crystal，performance and structure of photonic crystals

Photonic crystal is a new optical material which has low permittivity and Spatial periodic distribution. In the medium that has cycle distribution dielectric constant, electromagnetic wave in a certain frequency is prohibited. Usually these forbidden frequency interval is called "photonic band gap". The method for preparing photonic crystal includes laser etching, electron beam lithography, reactive ion beam etching, electrochemical corrosion and other advanced semiconductor technology. However, this technique has disadvantages in high cost, complex process and being not easy to get the three-dimensional photonic crystal. Recently based on the colloidal crystal template, the method in which the internal pore was filled to prepare three-dimensional ordered macroporous materials is attracted much attention, this method can obtain the complete three-dimensional photonic band gap. For the ordered macroporous materials is a kind of material having periodic changes’ refractive index, and it has good effect on photonic band gap. Photonic crystal has a very broad application prospects in electronic and optical communication field, it can be used in photonic crystal reflector, photonic crystal light-emitting diodes, photonic crystal filters, photonic crystal fiber, low threshold lasers etc. Optical properties of three-dimensional macroporous ordered materials can be adjusted by macroporous materials, hole spacing, refractive index and solid volume ratio changes. Our laboratory owe the related technologies of colloidal crystal self-assembled and photonic crystal structure to obtain colloidal crystals of highly ordered, large area two-dimension and controllable layer number. Construct a variety of system of inverse opal structure photonic crystal with colloidal crystal template method, including semiconductor, metal, alloy, oxide, polymer etc.

The self assembly of colloidal crystal from polystyrene spheres

Photographs of monolayered PS (556nm )on Si wafer showing a color changewhen the angle of incident white light is changed

The self-assembly of elliptical spheres

Optical photographs of the deposited Ge photonic crystal on the ITO glass substrate showing a color change when the angle of incident white light is changed.

Ge macropous fims electro-deposited from ionic liquid