Figure 1
From: All-optical routing and switching for three-dimensional photonic circuitry
Idea and setting of the proposed routing and switching scheme.
(a) A 2D arrangement of evanescently coupled waveguides, which allows constraining light to travel along defined paths by opto-optical switching. The crucial Y- and T-junction segments are highlighted in blue and orange, respectively and exemplary pulse sequences of the signal and the gating beam are shown in green and red. (b) Writing setup of waveguides using femtosecond laser pulses, which are focused into a bulk fused silica. The created refractive index change is dependent on the polarisation of the guided light, due to stress-induced birefringence of the material. Shown are resulting modal field distributions at λ = 800nm and the corresponding refractive index profiles for s- and p-polarisation. (c) Micrographs of the front facet of two basic elements of this scheme, the Y- and the T-junction. Note that the T-junction is shown with two different orientations of the elliptical waveguides, harnessing polarisation as additional degree of freedom. The input positions of the high power blocker beam and the low power signal beam are marked with a red and a white circle, respectively.
