Simultaneous direct UV-writing of channel waveguide and Bragg grating structures

Direct UV-writing is an ideal technique for rapid prototyping and small batch fabrication of integrated optical circuits. Based on the refractive index increase of a glass from exposure to a tightly focused UV beam. The translation of this beam relative to a suitable substrate allows the definition of 2-d waveguide structures such as s-bends and power couplers without the need for subsequent processing. Our alternative technique, Direct Grating Writing retains the advantages of Direct UV writing for channel definition but allowing both the grating and channel structure to be formed in the same process. Using this new technique, we present the fabrication of conventional channel waveguides and Bragg channel waveguides. We demonstrate the independence of the Bragg grating strength from the index difference of the channel waveguide, the sensitivity of this process as a characterization technique, and the ability to use this technique to fabricate more complex 2-D structures for integrated optical circuits. We finally present the fabrication of a range of gratings spanning the entire wavelength span commonly used for optical communication with no change in the equipment.