Silicon photonic contradirectional couplers using subwavelength grating waveguides.

We propose and demonstrate a novel design of contradirectional couplers in which a subwavelength grating (SWG) waveguide replaces one of the asymmetric waveguides of the conventional designs. The fabricated devices in silicon-on-insulator (SOI) platform show over 35 dB suppression of undesired codirectional coupling and larger than 120 nm operating range free from the interference of intrawaveguide reflections thanks to the large optical phase-mismatch between the segmented SWG waveguide and its nearby continuous waveguide. We study the effects of tailoring the period of the SWG waveguide, the gap distance between the two waveguides, and the coupling length on the spectral characteristics of the device where changing the gap distance from 100 nm up to 500 nm allows for bandwidths from 18.2 nm down to 0.9 nm.

[1]  Kazuhiro Ikeda,et al.  Wavelength selective coupler with vertical gratings on silicon chip , 2008 .

[2]  Ivan Glesk,et al.  Subwavelength grating filtering devices. , 2014, Optics express.

[3]  Wei Shi,et al.  Tunable nanophotonic delay lines using linearly chirped contradirectional couplers with uniform Bragg gratings. , 2014, Optics letters.

[4]  Sophie LaRochelle,et al.  Bandpass integrated Bragg gratings in silicon-on-insulator with well-controlled amplitude and phase responses. , 2015, Optics letters.

[5]  L. Chrostowski,et al.  Process calibration method for designing silicon-on-insulator contra-directional grating couplers. , 2015, Optics express.

[6]  Guomin Jiang,et al.  FSR-free add-drop filter based on silicon grating-assisted contradirectional couplers. , 2013, Optics letters.

[7]  Siegfried Janz,et al.  Waveguide sub‐wavelength structures: a review of principles and applications , 2015 .

[8]  Haishan Zeng,et al.  Perfectly registered multiphoton and reflectance confocal video rate imaging of in vivo human skin , 2013, Journal of biophotonics.

[9]  Wei Shi,et al.  Ultra-compact, flat-top demultiplexer using anti-reflection contra-directional couplers for CWDM networks on silicon. , 2013, Optics express.

[10]  Siva Yegnanarayanan,et al.  Toward ultimate miniaturization of high Q silicon traveling-wave microresonators. , 2010, Optics express.

[11]  Shon Schmidt,et al.  A silicon photonic biosensor using phase‐shifted Bragg gratings in slot waveguide , 2013, Journal of biophotonics.

[12]  I. Shubin,et al.  Wide bandwidth, low loss 1 by 4 wavelength division multiplexer on silicon for optical interconnects , 2011, 2011 Optical Fiber Communication Conference and Exposition and the National Fiber Optic Engineers Conference.

[13]  Wei Shi,et al.  Focusing sub-wavelength grating couplers with low back reflections for rapid prototyping of silicon photonic circuits. , 2014, Optics express.

[14]  J. Bowers,et al.  Silicon ring isolators with bonded nonreciprocal magneto-optic garnets. , 2011, Optics express.

[15]  Amos A. Hardy,et al.  Modes of periodically segmented waveguides , 1993 .

[16]  Wei Shi,et al.  Coupler-apodized Bragg-grating add-drop filter. , 2013, Optics letters.

[17]  Reza Ashrafi,et al.  Chirped Microwave Pulse Generation Using an Integrated SiP Bragg Grating in a Sagnac Loop , 2015, IEEE Photonics Technology Letters.

[18]  Siegfried Janz,et al.  Subwavelength grating periodic structures in silicon-on-insulator: a new type of microphotonic waveguide. , 2010, Optics express.

[19]  W Zhang,et al.  Contradirectional couplers in silicon-on-insulator rib waveguides. , 2011, Optics letters.

[20]  Wei Shi,et al.  Silicon photonic grating-assisted, contra-directional couplers. , 2013, Optics express.