Article

Optical modulator on silicon employing germanium quantum wells

Department of Electrical Engineering , Stanford University, Palo Alto, California, United States
Optics Express (Impact Factor: 3.49). 04/2007; 15(9):5851-9. DOI: 10.1364/OE.15.005851
Source: PubMed

ABSTRACT We demonstrate an electroabsorption modulator on a silicon substrate based on the quantum confined Stark effect in strained germanium quantum wells with silicon-germanium barriers. The peak contrast ratio is 7.3 dB at 1457 nm for a 10 V swing, and exceeds 3 dB from 1441 nm to 1461 nm. The novel side-entry structure employs an asymmetric Fabry-Perot resonator at oblique incidence. Unlike waveguide modulators, the design is insensitive to positional misalignment, maintaining > 3 dB contrast while translating the incident beam 87 mum and 460 mum in orthogonal directions. Since the optical ports are on the substrate edges, the wafer top and bottom are left free for electrical interconnections and thermal management.

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    • "Digital Object Identifier 10.1109/LPT.2011.2162724 done to demonstrate not only the possibility to modulate [8], [9] but also to detect [11] light using these MQWs in order to investigate the possibility to use the same structure for both modulator and photodetector. However, for applications in integrated photonics, modulation and detection properties in waveguide configuration have to be investigated as the performances of the devices depend not only on their material properties but also on the structures employed on the integrated circuits. "
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    ABSTRACT: The authors report on high speed operation of a Ge/SiGe multiple quantum-well waveguide photodetector. At , 10 Gb/s operation is demonstrated at wavelengths of 1405 and 1420 nm with a responsivity as high as 0.8 A/W. The device, 3 wide and 80 long, exhibits a dark current of 474 nA at a reverse bias of . These results pave the way for the use of Ge/SiGe multiple quantum-well structures as efficient active waveguide devices in silicon compatible integrated circuits.
    IEEE Photonics Technology Letters 10/2011; 23(20):1430-1432. DOI:10.1109/LPT.2011.2162724 · 2.18 Impact Factor
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    • "It opens a new approach to build CMOS-compatible optical modulators with low voltage drive, large bandwidth, and potentially very-low-energy consumptions. Several standalone QCSE electroabsorption modulators employing this physical mechanism have already been demonstrated [21], [22]. Monolithically integrating these QCSE modulators with the SOI waveguides can further reduce the device footprint, capacitance, and, even more importantly, power consumption. "
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    ABSTRACT: We propose an approach to monolithically integrate bulk germanium (Ge) or Ge quantum wells with silicon-on-insulator (SOI) waveguides through selective epitaxy and direct butt coupling. To prevent lateral epitaxial growth during the selective epitaxy, a dielectric insulating spacer layer is deposited on the sidewall facet of the SOI waveguide. With an SiO<sub>2</sub> spacer that is 20 nm thick, the additional insertion loss penalty can be as low as 0.13 dB. We also propose and demonstrate a robust, reliable, and complementary metal-oxide-semiconductor (CMOS)-compatible fabrication process to realize sub-30-nm spacers.
    IEEE Photonics Journal 09/2011; DOI:10.1109/JPHOT.2011.2162644 · 2.33 Impact Factor
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    • "A critical component in an optical interconnect is a high speed silicon optical modulator with low power/energy consumption and a small footprint [5]. Promising modulator candidates include carrier-injection silicon micro-ring modulators [6], carrier-depletion microdisk and microring modulators [7] [8], electro-absorption GeSi modulators [9], and GeSi quantum well modulators [10]. The spectral bandwidth of microcavities is usually less than 1 nm and that of GeSi modulators is about 15 nm. "
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    ABSTRACT: We present a 12.5 Gbps silicon micro-ring modulator achieved by carrier depletion in a lateral pn diode. Tunability of the resonant wavelength is accomplished by means of a micro-heater, with an efficiency of 2.36 mW/nm. OCIS codes: (230.3120) Integrated optics devices; (250.7360) Waveguide modulators; (200.4650) Optical interconnects.
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