Polymer based single mode optical waveguide for spectroscopy applications
In this work, we present for the first time, two dimensional low loss single mode optical waveguides fabricated with EPO materials. The waveguide geometry has a rectangular shape and it is buried between two EPOCLAD layers. Its refractive index distribution has a step-index profile with an index difference of 8.6x10(-3). Realized by polymer deposition, it consists mainly, of a stack of EPOCLAD/EPOCORE/EPOCLAD layers sandwiched between two thick glass substrates. The waveguide dimensions are: 3 x 2.2 mu m(2). A cleaved single mode optical fiber, dedicated to the visible range (658 nm), is used to perform all the optical characterizations. The structure demonstrates an overall insertion loss of 2.6 dB and a numerical aperture of 0.19. Such waveguides will be used to create standing wave interference pattern using a high reflectance mirror embedded at the waveguide exit. Sampling of the pattern using an array of nano-antennas deposited on top of the waveguide yields information about the spatial distribution of the electrical field inside the waveguide. Hence, the spectral content of the signal can be deduced and the developed architecture demonstrates a strong potential for spectroscopic applications.