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Coupled mode theory
About: Coupled mode theory is a research topic. Over the lifetime, 2868 publications have been published within this topic receiving 58569 citations.
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02 Nov 2016
TL;DR: In this paper, the optical coupling between two strongly coupled highly multi-mode fibers is studied and the effects of the differences between two fiber cores on the coupling process are revealed. But the results of the experiment were limited.
Abstract: The optical coupling between two strongly-coupled highly multi-mode fibers is studied. The coupling process is measured in experiment. The effects of the differences between two fiber cores on the coupling process are revealed.
TL;DR: Yang et al. as mentioned in this paper reported in-situ measurements of the bound states in the radiation continuum (BICs) in photonic crystal slabs, which was confirmed with a rigorously coupled-wave analysis.
Abstract: Photonic crystal slabs have been subject to research for more than a decade, yet the existence of bound states in the radiation continuum (BICs) in photonic crystals has been reported only recently [1]. A BIC is formed when the radiation from all possible channels interferes destructively, causing the overall radiation to vanish. In photonic crystals, BICs are the result of accidental phase matching between incident, reflected and in-plane waves at seemingly random wave vectors [2].
While BICs in photonic crystals have been discussed previously using reflection measurements, we reports for the first time in-situ measurements of the bound states in the continuum in photonic crystal slabs. By embedding a photodetector into a photonic crystal slab we were able to directly observe optical BICs. The photonic crystal slabs are processed from a GaAs/AlGaAs quantum wells heterostructure, providing intersubband absorption in the mid-infrared wavelength range. The generated photocurrent is collected via doped contact layers on top and bottom of the suspended photonic crystal slab.
We were mapping out the photonic band structure by rotating the device and by acquiring photocurrent spectra every 5°. Our measured photonic bandstructure revealed several BICs, which was confirmed with a rigorously coupled-wave analysis simulation. Since coupling to external fields is suppressed, the photocurrent measured by the photodetector vanishes at the BIC wave vector. To confirm the relation between the measured photocurrent and the Q-factor we used temporal coupled mode theory, which yielded an inverse proportional relation between the photocurrent and the out-coupling loss from the photonic crystal. Implementing a plane wave expansion simulation allowed us to identify the corresponding photonic crystal modes.
The ability to directly measure the field intensity inside the photonic crystal presents an important milestone towards integrated opto-electronic BIC devices. Potential applications range include nonlinear optics, nano-optics, sensing and optical computing.
This research was supported by the Austrian Science Fund FWF (Grant No. F2503-N17), the PLATON project 35N, the “Gesellschaft fur Mikro- und Nanoelektronik” GMe and the European Research Council (Grant no. 639109).
[1] C.W. Hsu et al. “Observation of trapped light within the radiation continuum”, Nature 499, 188 (2013)
[2] Y. Yang Y et al., “Analytical Perspective for Bound States in the Continuum in Photonic Crystal Slabs”, Phys Rev Lett 113, 037401 (2014)
TL;DR: In this article, a generalized coupled mode theory has been developed to analyze curved multi-waveguides from the reciprocity theorem, taking account of the field deformation due to waveguide bending, and the nonorthogonality and phase interference between local guided modes in different bent waveguides.
Abstract: A generalized coupled mode theory has been developed to analyze curved multiwaveguides from the reciprocity theorem. A simple relationship between local coupling coefficients and local nonorthogonal coefficients is given. Our theory takes account of the field deformation due to waveguide bending, and the nonorthogonality and phase interference between local guided modes in different bent waveguides. It is noted that the generalized coupled mode theory satisfies the reciprocity theorem and power conservation.
09 Jun 1986
TL;DR: The first insights into the operation of diode laser arrays were obtained through coupled-mode theory calculations, which assume weak coupling between neighboring channels that operate almost independently of one another as mentioned in this paper.
Abstract: The first insights into the operation of diode laser arrays were obtained through coupled-mode theory calculations, which assume weak coupling between neighboring channels that operate almost independently of one another. These calculations produced (for n-coupled waveguides) a set of n eigenmodes designated in the literature as "supermodes",1 which have since dominated the thinking concerning array operation. In particular, gain-guided arrays have been described using coupled-mode theory with complex coupling coefficients,2 a picture reinforced largely by the fact that such arrays generally exhibit a two-lobed far-field emission pattern which is suggestive of the highest-order supermode of an index-guided array.
14 Oct 2009
TL;DR: In this article, the effect of interfacial strain on the optical properties of a one-dimensional photonic crystal, with special emphasis on modified form birefringence coming from strain induced local anisotropy, is described.
Abstract: We use an exact coupled‐mode theory to describe the effect of interfacial strain on the optical properties of a one‐dimensional photonic crystal, with special emphasis on modified form birefringence coming from strain‐induced local anisotropy. Parallel and perpendicular states of polarization being totally decoupled, we easily extract in each case an effective coupling constant and an effective detuning from the transfer matrix of the unit cell.