Integration of precisely aligned lenslet arrays with waveguide arrays

We present a method to fabricate in situ lens arrays on the edge of waveguide arrays that are embedded in a printed circuit board. This fabrication method can guarantee precise alignment between the lenslet and the waveguide arrays, by directly overlaying the lenslet pattern on the waveguide cores. Each fabricated lenslet has a numerical aperture of 0.1, and the beam through it has a divergence angle of 3.29 deg, close to that of a perfectly aligned commercial lenslet array.