Traveling-wave Uni-Traveling Carrier Photodiodes for continuous wave THz generation

UCL Electronic and Electrical Engineering, Torrington Place, London WC1E 7JE, UK.
Optics Express (Impact Factor: 3.49). 05/2010; 18(11):11105-10. DOI: 10.1364/OE.18.011105
Source: PubMed


The design, experimental evaluation and performance of a Traveling-Wave Uni-Traveling Carrier photodiode for Terahertz generation are described and its advantages in terms of frequency response are demonstrated. The device delivered 148 microW at 457 GHz, 24 microW at 914 GHz when integrated with resonant antennas and 105 microW at 255 GHz, 30 microW at 408 GHz, 16 microW at 510 GHz and 10 microW at 612 GHz. Record levels of Terahertz figure of merit (PTHz/Popt2 in W(-1)) were achieved ranging from 1 W(-1) at 110 GHz to 0.0024 W(-1) at 914 GHz.

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    • "The bandwidth of PDs in this paper is lower than other works on Si [7], [8], [10]. It can be improved by shrinking the size of the active regions and using the design of uni-traveling-carrier PDs [32], [33]. The responsivity of the WGPD device can be much improved with better coupling. "
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    ABSTRACT: We report selective-area growth of high-crystalline-quality InGaAs-based photodetectors with optimized InP/GaAs buffers on patterned (100)-oriented silicon-on-insulator (SOI) substrates by metal-organic chemical vapor deposition. The composite GaAs and InP buffer was grown using a two-temperature method. The island morphology of the low-temperature GaAs nucleation layer inside the growth well of the SOI substrate was optimized. A medium temperature GaAs layer was inserted prior to the typical high-temperature GaAs to further decrease the dislocation densities and antiphase boundaries. Both normal-incidence photodetectors and butt-coupled waveguide photodetectors were fabricated on the same substrate and showed a low dark current and high-speed performance. This result demonstrates a good potential of integrating photonic and electronic devices on the same Si substrate by direct epitaxial growth.
    IEEE Journal of Selected Topics in Quantum Electronics 11/2014; 20(6):1-7. DOI:10.1109/JSTQE.2014.2321278 · 2.83 Impact Factor
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    • "integrated two UTC devices on the same chip and their combined power output showed record high power of 1 mW at 300 GHz [17]. To date, the best results in waveguide based devices have been obtained in work when the standard UTC structure was used in combination with an optimized pseudo TW design [18], [19]. The devices were not full travelling wave structures as this can only be achieved in periodic structures. "
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    Journal of Lightwave Technology 01/2014; PP(3-99):1-1. DOI:10.1109/JLT.2014.2355137 · 2.97 Impact Factor
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    • "Uni-traveling carrier (UTC) and partially depleted absorber (PDA) designs have shown power-handling [1] and bandwidth [2] performances far superior to the best p-i-n detectors. Germanium detectors on silicon are attractive due to their low cost and the high thermal conductivities of Ge and Si, and efforts thus far yielded a p-i-n structure with a 49GHz bandwidth [3] and one with a large-signal compression current of 60mA [4]. "
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    ABSTRACT: A Ge/Si uni-traveling carrier (UTC) photodetector is demonstrated for the first time. The device has a bandwidth of 15GHz and no saturation of the DC response is visible at −1V up to 28dBm input power.
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