  Valley photonic crystal (VPhC) waveguides have attracted much attention
because of their ability to enable robust light propagation against sharp
bends. However, their demonstration using a complementary
metal-oxide-semiconductor (CMOS)-compatible process suitable for mass
production has not yet been reported at the telecom wavelengths. Here, by
tailoring the photomask to suppress the optical proximity effect, VPhC patterns
comprising equilateral triangular holes were successfully fabricated using
photolithography. We optically characterized the fabricated VPhC devices using
microscopic optics with near-infrared imaging. For comparison, we also
fabricated and characterized line-defect W1 PhC waveguides, in which the
transmission intensities decreased at some regions within the operating
bandwidth when sharp turns were introduced into the waveguide. In contrast, the
developed VPhC waveguides can robustly propagate light around the C-band
telecommunication wavelengths, even in the presence of sharp bends. Our results
highlight the potential of VPhC waveguides as an interconnection technology in
silicon topological photonic integrated circuits.
