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Ultrafast Modulation and Switching of Quantum-Well Lasers using Terahertz FieldsModulation and switching of semiconductor lasers are important for laser-based information technology. Typically the speed of modulation and switching is limited by interband processes such as stimulated and spontaneous recombinations which occur on a nanosecond time scale. This is why the diode laser modulation has been restricted to tens of GHz. Modulation at higher speed is highly desirable as the information technology enters into the so-called tera-era. In this paper, we study the possibility of utilizing THz-field-induced plasma heating to modulate quantum-well lasers. This is a timely study since, with the advancement of THz solid-state sources and free-electron lasers, THz physics and related technology is currently coming out of its infancy. The investigation of interplaying THz and optical fields is also of intruiging fundamental interest. First, we introduce theoretical plasma heating results for the quantum-well optical amplifier in the presense of an intense half-cycle THz pulse. The heated carrier distributions are then utilized to calculate the THz-pulse-induced change in refractive index and gain profile. Since the electron-hole-plasma is heated using intraband transitions, we circumvent the usual complications due to an overall change in density, and the nonlinear recovery is governed solely by the carrier-LO-phonon interactions, typically 5 ps for a complete recovery. This procedure implies THz and sub-THz switching and recovery rates, respectively; using either gain modulation or index modulation. Plasma heating via steady-state THz fields is also studied. Finally, numerical simulation of a coupled set of equations to investigate the THz modulation based on a simplified model for quantum-well lasers is presented. Our results show that a semiconductor laser can be modulated at up to 1 THz with little distortion with a THz field amplitude at the order of a few kV/cm. Laser responses to a change in THz frequency will be shown. Constraints, practicalities, and applications will be discussed.
Document ID
20020074084
Acquisition Source
Ames Research Center
Document Type
Conference Paper
Authors
Ning, Cun-Zheng
(MRJ Technology Solutions, Inc. Moffett Field, CA United States)
Hughes, S.
(Washington State Univ. Pullman, WA United States)
Citrin, D.
(Washington State Univ. Pullman, WA United States)
Saini, Subhash
Date Acquired
August 20, 2013
Publication Date
January 1, 1998
Subject Category
Lasers And Masers
Meeting Information
Meeting: Photonics West
Location: San Jose, CA
Country: United States
Start Date: January 23, 1999
End Date: January 29, 1999
Funding Number(s)
PROJECT: RTOP 519-40-12
CONTRACT_GRANT: NAS2-14303
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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