Stripe-based Collimating Silica Planar Waveguide for a Free-space Wavelength Selective Cross Connect

A novel silica waveguide lens for free-space optical cross connects

“…In this paper we change the effective mode index of a waveguide layer by introducing a core-cladding stripe structure [5] in a waveguide. In this case, the effective mode index for the stripe region can be described as:…”

“…However, a free-space-based wavelength routing would require many bulky optical components especially for collimation and polarization compensation. In particular, a large-scale node will require arrays of micro lenses that lead to difficult alignment and increased assembly cost [5].…”

“…An alternative in depleting the bulky components is by utilizing the planar lightwave circuit (PLC) for beam collimation [5]. For this purpose, various approaches involving diffraction [6,7], reflection [8,9], and refraction [10] have been proposed.…”

“…We propose a novel refraction-based waveguide collimator that employs a stripe structure for phase modulation purpose [5]. As with other types of waveguide collimators, due to the nature of PLC that is usually designed two dimensionally, the stripe-based collimator is also only capable of collimating beam laterally and leaves the vertical direction totally exposed to beam divergence.…”

“…As with other types of waveguide collimators, due to the nature of PLC that is usually designed two dimensionally, the stripe-based collimator is also only capable of collimating beam laterally and leaves the vertical direction totally exposed to beam divergence. This could be resolved by combining the array of collimators with a single cylindrical lens [5,9] which would still fare better, in terms of assembly difficulty, than using array of micro lenses.…”