RLE Recent Papers

Transmissive silicon photonic dichroic filters with spectrally selective waveguides

Emir Salih Magden, Nanxi Li, Manan Raval, Christopher V. Poulton, Alfonso Ruocco, Neetesh Singh, Diedrik Vermeulen, Erich P. Ippen, Leslie A. Kolodziejski& Michael R. Watts

DOI: 10.1038/s41467-018-05287-1


Many optical systems require broadband filters with sharp roll-offs for efficiently splitting or combining light across wide spectra. While free space dichroic filters can provide broadband selectivity, on-chip integration of these high-performance filters is crucial for the scalability of photonic applications in multi-octave interferometry, spectroscopy, and wideband wavelength-division multiplexing. Here we present the theory, design, and experimental characterization of integrated, transmissive, 1 × 2 port dichroic filters using spectrally selective waveguides. Mode evolution through adiabatic transitions in the demonstrated filters allows for single cutoff and flat-top responses with low insertion losses and octave-wide simulated bandwidths. Filters with cutoffs around 1550 and 2100 nm are fabricated on a silicon-on-insulator platform with standard complementary metal-oxide-semiconductor processes. A filter roll-off of 2.82 dB nm−1 is achieved while maintaining ultra-broadband operation. This new class of nanophotonic dichroic filters can lead to new paradigms in onchip communications, sensing, imaging, optical synthesis, and display applications.