US Patent 11982848 Optical fiber-to-chip interconnection

An apparatus includes a fiber-optic connector configured to be connected between one or more optical fibers having fiber cores and a photonic integrated circuit (PIC) including vertical-coupling elements. The fiber-optic connector includes a polarization beam splitter and a patterned birefringent plate. The polarization beam splitter splits an incident light beam from a fiber core into first and second beams having first and second polarizations, respectively. The patterned birefringent plate includes a first region (having a first optical birefringence) and a second region (having a second optical birefringence). The difference in the first and second optical birefringence is caused by (i) applying localized heating to the first region without applying localized heating to the second region to cause the first region to have a lower birefringence as compared to the second region, or (ii) applying different amounts of localized heating to the first and second regions to produce different birefringence.