Index profiling of three-dimensional optical waveguides by the propagation-mode near-field method

Fabrication of optical waveguides using proton beam writing

“…The fiber was then butt coupled to the waveguides and the mode imaged using an infinity corrected 40 Â long working distance objective coupled to a 12 bit cooled charge coupled device (CCD) camera (Qimaging Retiga EXi). The high dynamic range and the low dark noise of this camera improves the image quality of the modes making it possible to use them in order to recover the refractive index of the waveguides using the propagation mode near field method [15,16]. Loss measurements were performed by imaging the light scattered out from the plane of the waveguide using a stereo zoom microscope [17].…”

Index Profile Reconstruction of Ti: LiNbO3 Structures and Loss Bending Evaluation from Near-Field Measurements

“…By this iterative technique, the refractiveindex profiles in an array of channel waveguides can be determined from near-field measurements. The present procedure does not involve commonly used calculations of the derivatives of the field profiles [3] because these require an extremely high -and difficult to achieveaccuracy of the near-field measurements.…”

“…Both of these problems have attracted much attention. Methods for the evaluation of refractive-index profiles from near-field measurements have been proposed [1][2][3]. In this paper, a simple computational procedure for reconstructing profiles of single-mode Ti:LiNbO 3 waveguides is described.…”

Measuring system for registration of near-field power distribution in modes of planar and strip waveguides

“…For the waveguides consisting of many modes, turning points of wave vector (the depth of beam penetration in a structure) are marked, and on their basis the distribution of refractive index is marked the more precisely the more modes are in a given structure. For the waveguides consisting of few modes, there exists a method based on the ratio ofthe distribution of the electric field of light wave amplitude to the distribution ofthe refractive index ofa given structure[2,3]. 3.2.…”