  We demonstrate three and four input multiports in a three dimensional glass
platform, fabricated using the femtosecond laser direct-write technique.
Hong-Ou-Mandel (HOM) interference is observed and a full quantum
characterisation is performed, obtaining two photon correlation matrices for
all combinations of input and output ports. For the three-port case, the
quantum visibilities are accurately predicted solely from measurement of the
classical coupling ratios.
