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Proceedings Paper

Quantum dots: a new approach to low Vπ optical modulators
Author(s): Elizabeth Twyford Kunkee; Peter M. Livingston; Steve Holm
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Paper Abstract

Preliminary analysis has shown that quantum dots enable tens of millivolt-range operation of phase-shifters in a semiconductor Mach-Zehnder interferometer modulator. Our methodology based upon the quantum dot experimental work of Hse et al, makes use of his measured exciton line shapes to estimate refractive index changes in a PIN structure in which the intrinsic laser is loaded with self-organizing quantum dots and their associated wetting layers. We consider both forward and reversed bias cases; in the former, the interferometer phase shift sections become DFB lasers, and in the latter, the phase shift is caused by the quantum-confined Stark effect (QCSE). With the latter, we found a trade-off between low operating voltage and modulating bandwidth. For a phase shifter insertion loss of 5 dB, a 250-micron long phase section will yield a pi/2 control voltage of 50 mV at a bandwidth of around 18 GHz. Ifi 90 mV control voltage swing can be tolerated, the modulator bandwidth increases to 30 GHz. If a resonant tunneling diode (RTD) is made part of the assembly, the local E-field is enhanced by a factor of 5 to 10, thereby reducing the drive requirements even further. Similar, though narrower bandwidth results were noted for the DFB laser phase modulator concept.

Paper Details

Date Published: 19 June 2003
PDF: 15 pages
Proc. SPIE 4987, Integrated Optics: Devices, Materials, and Technologies VII, (19 June 2003); doi: 10.1117/12.478330
Show Author Affiliations
Elizabeth Twyford Kunkee, TRW, Inc. (United States)
Peter M. Livingston, TRW, Inc. (United States)
Steve Holm, TRW, Inc. (United States)


Published in SPIE Proceedings Vol. 4987:
Integrated Optics: Devices, Materials, and Technologies VII
Yakov S. Sidorin; Ari Tervonen, Editor(s)

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