Introduction to Integrated Optics: Characterisation and Modelling of Optical Waveguides

Graded-index profile analysis from M-line, optical polarimetry, and EDS measurements of glass waveguides produced by K+/Ag+ion-exchange combinations

“…1,2 The data obtained from the propagating modes in the m-line technique, associated with their corresponding angles of incidence (synchronous angles), were analyzed by the inverse WKB method. 3 In Fig. 1 we show as an example the refractive index reconstruction of an HKN2 waveguide.…”

Sol-gel glass waveguides

“…To evaluate propagation losses one can use a TV camera to collect the light scattered out of the plane of the waveguide. If the scattering centers are distributed evenly enough, which is almost always the case, the signal measured by the camera is proportional to the light actually present in the waveguide and losses can be easily evaluated through an exponential fit [ 1 ]. A good waveguide should exhibit propagation loss lower than 1 dB/cm, in order to be usable in integrated optics circuits.…”

“…1). If the film is homogeneous and sufficiently thick, it can constitute a step-index waveguide; one or more propagation modes (one for each allowed integer value of m) will be observed by launching light into it, according to the 4~ngd cos O -2~ba -2q~s = 2m~r, (1) where ng and d are the refractive index and thickness of the guiding layer respectively, m is the mode order, q~i are the phase shifts at the interfaces, which depend on the refractive indices of cladding and substrate. Singlemode waveguides on fused silica (n ~ 1.45) or sodalime (n ~ 1.51) substrates require a thickness of the guiding layer typically in the range 0.2 to 5/zm, depending on the index of the layer itself(e.g., in the range 1.65 to 1.512).…”

“…Since the behaviour of a waveguide, which depends as a first issue on the propagation constant of the mth guided mode fin "~-ng sin | is the result of the choice of the geometrical structure and of all materials involved in its realisation, it is very important to achieve a high degree of control in the refractive index of the deposited layers. An experimental assessment of the actual refractive index and thickness of the guiding layer can be obtained using m-lines spectroscopy technique, i.e., by measuring the propagation constants of the guiding modes through a prism coupler [1].…”

Brillouin scattering in planar waveguides. II. Experiments

“…The losses were evaluated by fitting the intensity to an exponential decay function, assuming a homogeneous distribution of the scattering centers in the film. 21 The measurements were performed by exciting the transverse electric TE 0 mode of the waveguide with a He-Ne laser operating at 632.8 nm.…”