ntegrated Bragg Diffraction Grating with Alternating Perturbation Cancellation

This invention proposes a modification to the standard design of perturbations in Bragg devices or Bragg gratings. In the standard design, and more specifically in the design and fabrication of Bragg gratings in integrated optical technologies, symmetrical lateral geometric perturbations are manufactured to reflect light propagated through the optical waveguide at a specific wavelength. These perturbations must be spaced according to what is known as the Bragg period, which depends on the operating wavelength and the refractive index of the waveguide used. This Bragg period can be very small in dimension—approximately 240 nm (see examples in the attached document)—which is a highly limiting factor when using integrated Bragg gratings in technological processes that employ photolithographic fabrication methods with resolutions between 0.6 and 1 micron. These resolution values are very common in many fabrication facilities that use direct or stepper photolithography. The invention proposes alternating the elimination of perturbations between the two sides of the integrated Bragg grating (see attached document). This approach significantly increases the minimum spacing between perturbation features, thereby simplifying their fabrication at the cost of a reduction in the net strength of the reflected field. This reduction in strength is not an issue in most cases and practical designs. Furthermore, the technique allows for the application of classical design strategies, such as apodization, chirping, or both, in the design of the complete device.