Silicon Photonics|114 Article(s)
Germanium tin: silicon photonics toward the mid-infrared [Invited]
E. Kasper, M. Kittler, M. Oehme, and T. Arguirov
Germanium tin (GeSn) is a group IV semiconductor with a direct band-to-band transition below 0.8 eV. Nonequilibrium GeSn alloys up to 20% Sn content were realized with low temperature (160°C) molecular beam epitaxy. Photodetectors and light emitting diodes (LEDs) were realized from in situ doped pin junctions in GeSn on Ge virtual substrates. The detection wavelength for infrared radiation was extended to 2 μm with clear potential for further extension into the mid-infrared. GeSn LEDs with Sn content of up to 4% exhibit light emission from the direct band transition, although GeSn with low Sn content is an indirect semiconductor. The photon emission energies span the region between 0.81 and 0.65 eV. Optical characterization techniques such as ellipsometry, in situ reflectometry, and Raman spectroscopy were used to monitor the Sn incorporation in GeSn epitaxy.
Photonics Research
  • Publication Date: Jul. 19, 2013
  • Vol. 1, Issue 2, 02000069 (2013)
Electrical nonlinearity in silicon modulators based on reversed PN junctions
Sheng Yu, and Tao Chu
The electrical nonlinearity of silicon modulators based on reversed PN junctions was found to severely limit the linearity of the modulators. This effect, however, was inadvertently neglected in previous studies. Considering the electrical nonlinearity in simulation, a 32.2 dB degradation in the CDR3 (i.e., the suppression ratio between the fundamental signal and intermodulation distortion) of the modulator was observed at a modulation speed of 12 GHz, and the spurious free dynamic range was simultaneously degraded by 17.4 dB. It was also found that the linearity of the silicon modulator could be improved by reducing the series resistance of the PN junction. The frequency dependence of the linearity due to the electrical nonlinearity was also investigated.
Photonics Research
  • Publication Date: Mar. 06, 2017
  • Vol. 5, Issue 2, 02000124 (2017)
Compact on-chip 1×2 wavelength selective switch based on silicon microring resonator with nested pairs of subrings
Jiayang Wu, Pan Cao, Ting Pan, Yuxing Yang, Ciyuan Qiu, Christine Tremblay, and and Yikai Su
Photonics Research
  • Publication Date: Jan. 15, 2015
  • Vol. 3, Issue 1, 01000009 (2015)
Compact, submilliwatt, 2 × 2 silicon thermo-optic switch based on photonic crystal nanobeam cavities
Huanying Zhou, Ciyuan Qiu, Xinhong Jiang, Qingming Zhu, Yu He, Yong Zhang, Yikai Su, and Richard Soref
We propose and experimentally demonstrate a 2×2 thermo-optic (TO) crossbar switch implemented by dual photonic crystal nanobeam (PCN) cavities within a silicon-on-insulator (SOI) platform. By thermally tuning the refractive index of silicon, the resonance wavelength of the PCN cavities can be red-shifted. With the help of the ultrasmall mode volumes of the PCN cavities, only ~0.16 mW power is needed to change the switching state. With a spectral passband of 0.09 nm at the 1583.75 nm operation wavelength, the insertion loss (IL) and crosstalk (CT) performances were measured as IL(bar)= 0.2 dB, CT(bar)= 15 dB, IL(cross)= 1.5 dB, and CT(cross)= 15 dB. Furthermore, the thermal tuning efficiency of the fabricated device is as high as 1.23 nm/mW.
Photonics Research
  • Publication Date: Feb. 28, 2017
  • Vol. 5, Issue 2, 02000108 (2017)
Hybrid optical wavelength demultiplexer and power combiner for TWDM PON
Chunsheng Li, Xinyou Qiu, and Xun Li
In this paper, we have proposed a hybrid optical wavelength demultiplexer and power combiner for a hybrid time- and wavelength-division multiplexing (TWDM) passive optical network (PON), i.e., a single passive optical device that functions as a 1×N wavelength demultiplexer for distributing the downstream signal in multiple wavelengths from the optical line terminal (OLT) to the N optical network units (ONUs), and simultaneously as an N×1 power combiner for collecting the upstream signal in the same wavelength from the N ONUs to the OLT. Through a design example of a 32 channel hybrid optical wavelength demultiplexer and power combiner on the silicon-on-insulator platform, our numerical simulation result shows that the insertion loss and adjacent channel crosstalk of the downstream wavelength demultiplexer are as low as 4.6 and 16.3 dB, respectively, while the insertion loss and channel non-uniformity of the upstream power combiner can reach 3.5 and 2.1 dB, respectively. The proposed structure can readily be extended to other material platforms such as the silica-based planar lightwave circuit. Its fabrication process is fully compatible with standard clean-room technologies such as photo-lithography and etching, without any complicated and/or costly approach involved.
Photonics Research
  • Publication Date: Feb. 28, 2017
  • Vol. 5, Issue 2, 02000097 (2017)
Strip-loaded waveguide-based optical phase shifter for high-efficiency silicon optical modulators
Yuriko Maegami, Guangwei Cong, Morifumi Ohno, Makoto Okano, and Koji Yamada
Photonics Research
  • Publication Date: Nov. 15, 2016
  • Vol. 4, Issue 6, 06000222 (2016)