Cambridge NanoTech Inc.

INTEGRATED OPTICS

For integrated optics and planar waveguides, the excellent uniformity of ALD can offer a well-controlled device operation, e.g., in the phase sensitive devices. In addition to this, ALD offers a way to fabricate antireflective or reflective waveguide end coatings as well as to connect different waveguide sections with low loss, both these directly on a wafer level. This is possible due to the conformal growth of ALD. In this example, ALD was used in preparing erbium (Er)-doped waveguides. Ridge-type Er-doped Al2O3 waveguides were patterned on silica-coated silicon wafers using photolithography and wet etching. Optical absorption, emission, fluorescence lifetime, and signal enhancement measurements were performed. Polarization dependence of the absorption spectrum and birefringence of the waveguide were measured. The material showed strong absorption and wide emission spectrum around 1530 nm with full-width at half-maximum of 52 nm. Signal enhancement of 6 dB was measured for a 3.9-cm-long waveguide.

In another example, high-performance true zero-order optical retarders have been realized based on all-dielectric immersion nanogratings through the ALD technique. The all-dielectric immersion nanograting structure opens a path for innovative nanograting based optical devices and (stacked) integrated optical devices.