upon an angle between the first and second portions at least one of the waveguides may have an amorphous silicon material coating application_number US 6847705 A description it is to be understood that the figures and descriptions of the present invention have been simplified to illustrate elements that are relevant for a clear understanding of the present invention while eliminating for purposes of clarity many other elements found in typical optical systems and methods of making and using the same those of ordinary skill in the art will recognize that other elements are desirable and or required in order to implement the present invention however because such elements are well known in the art and because they do not facilitate a better understanding of the present invention a discussion of such elements is not provided herein according to an aspect of the present invention multi mode interference mmi couplers with arbitrary coupling ratios may be provided and a method for making the same is provided according to an aspect of the present invention optical waveguides may be at least partially coated e g encapsulated to improve their performance an amorphous silicon u03b1 si material may be used to encapsulate the guides according to an aspect of the present invention electro refractive modulation may be used in combination with ring resonators mmi couplers may be used to provide reproducible coupling ratios which may be particularly useful in electro optic applications or when the resonators are used in optical filters referring now to fig1 there is shown a.