Available Technology

Anti-reflection Coating for the Pass-band of Photonic Bandgap Crystal

Conventional PBG structures, which consist of alternating layers of high index and low index materials, are not optimal since some portion of light is reflected in the pass-band, even though high reflectance is supposed to be achieved only around the central wavelength (stop-band). Also, anti-reflection coatings, another way of suppressing the reflectance, cannot have both high transmissive pass-band and high reflective stop-band at the same time, which limits the range of its applications.
Patent Abstract: 
The invention provides the method to maximize transmission through the pass-band while preserving high reflection of light through the stop-band of a photonic bandgap crystal. The method involves forming a PBG crystal via alternating deposition of layers with high index and low index material (ex. Si/SiO2) and coating an ARC layer on top of PBG crystal, with optimally designed thickness and indices of each layer. The invention also includes a method of using a SiON layer as an ARC and adjusting its index by controlling NO concentration in a gaseous composition step.
Maximizing light transmission through the pass-band of a PBG crystal - Preserving high reflection of light through the stop-band of a PBG crystal - Can be fabricated using various fabrication schemes, such as CVD, sputtering or e-beam deposition - Wide range of applications in photonic and optoelectronic devices and systems
Ivan Celanovic
Lab Representatives
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