Wafer-level inspection platform on high-volume photonic integrated circuits for drastic reduction of testing time

High Density Multi-Channel Passively Aligned Optical Probe for Testing of Photonic Integrated Circuits

“…Edge-coupled devices have the advantage of broadband optical response, but access to the waveguide is not available until after the chips have been singulated from the wafer. Since the mode size of a standard single-mode fiber (SMF) and the waveguide may differ significantly (typically a factor [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20], either mode-size converters are required or sub-micron alignment may be needed, or a combination of both. Grating couplers couple out-of-plane to a near-vertical direction and are manufacturable in thin membranetype high-contrast waveguides, typically in Si-based integration technologies.…”

“…They are accessible before chip singulation and thus allow on-wafer probing, but they are wavelength and polarization dependent and induce reflections [9]. These structures are typically designed to have a modefield-diameter (MFD) of around 10 µm, matching that of an SMF, which allows for a more relaxed alignment (1-dB penalty within ±2.5 µm offset), but with a trade-off on angular alignment [10], [11].…”