  Next generation optoelectronic systems will require the efficient transfer of
optical signals between many discrete photonic components integrated onto a
single substrate. While modern assembly processes can easily integrate
thousands of electrical components onto a single board, photonic assembly is
far more challenging due to the wavelength-scale alignment tolerances required.
Here we address this problem by introducing an alignment-free photonic coupler
robust to x, y, z displacement and angular misalignment. This alignment-free
coupler engineers a translationally-invariant evanescent interaction between
waveguides by intersecting them at an angle, which enables a lateral and
angular alignment tolerance fundamentally larger than non-evanescent approaches
such as edge coupling. We show that our approach can function as a universal
photonic connector interfacing photonic integrated circuits and microchiplets
across different platforms. As a potential use case, we describe a new type of
self-aligning photonic circuit board enabled by our approach that greatly
simplifies assembly of complex optoelectronic systems.
