Article

Coupled-mode theory and propagation losses in photonic crystal waveguides

University of Glasgow, Glasgow, Scotland, United Kingdom
Optics Express (Impact Factor: 3.49). 07/2003; 11(13):1490-6. DOI: 10.1364/OE.11.001490
Source: PubMed

ABSTRACT Mode coupling phenomena, manifested by transmission "ministopbands", occur in two-dimensional photonic crystal channel waveguides. The huge difference in the group velocities of the coupled modes is a new feature with respect to the classical Bragg reflection occurring, e.g., in distributed feedback lasers. We show that an adequate ansatz of the classical coupled-mode theory remarkably well accounts for this new phenomenon. The fit of experimental transmission data from GaAs-based photonic crystal waveguides then leads to an accurate determination of the propagation losses of both fundamental and higher, low-group-velocity modes.

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    • "The problem of coupling between localized states in photonic crystals, i.e waveguide or surface modes, has been studied recently [9] [10] [11] [12]. In [8], Olivier et al apply the coupled mode theory (CMT) to the problem of waveguides in photonic crystals. They analyze the cases of multimode waveguides and the coupling between counter propagating waves, finding very simple analytic relations involving the basic parameters of these modes, such as the coupling coefficient for counter propagating modes. "
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    • "Mode conversion phenomenon is analytically and experimentally investigated in PCCW as a periodic waveguide with similar structure to the substrate integrated waveguide [7]. As it is shown, mode conversion is appeared by a dip in the transmission spectrum of the fundamental mode and energy is transferred to the higher order mode which propagates backward. "
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    • "These waveguides are primarily based on the in-plane photonic band gap confinement. Our main system of interest consists of heterostructure-type or ''substrate-type'' confinement in the third direction, whereby a low-index contrast material system, such as AlGaAs/GaAs or InP/ InGaAsP is exploited to confine light vertically [1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13]. However, membranes (i.e., thin slabs of perforated semiconductor surrounded by air) will be specifically considered in Section 6 of this paper, in the spirit of the striking results of the Kyoto group [14] [15] [16]. "
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