General matrix theory of self-imaging in multimode interference (MMI) couplers

In this letter, a mode multiplexer/demultiplexer (MUX/DEMUX) for multicore fibers with 2D aligned cores is proposed. The device is based on the concept of 2D multimode interference (2DMMI) effect. If the 2D waveguide array is aligned within a square lattice, the supermodes of the array will obey the sinusoidal function and coincide with the transfer matrix of the 2DMMI couplers with phase shifter arrays. Therefore, a mode MUX/DEMUX with high mode extinction ratio can be realized based on this principle.

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“…For 2DMMI couplers with a square shape, the length of the two dimensional MMI coupler is set to be [8], [14] …”

Section: B Theory Of Two Dimensional MMI Couplermentioning

confidence: 99%

“…MMI couplers [7], [8] have been investigated as mode MUXs/DEMUXs for multimode waveguides [9], [10]. Recently, one dimensional (1D) MMI couplers have been used as MUXs/DEMUXs for the MCFs with equally spaced 1D fiber core arrays [11].…”

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confidence: 99%

A Mode MUX/DEMUX for Multicore Fibers With 2D Core Arrays

Zhou

Gallion

2014

IEEE Photon. Technol. Lett.

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“…For simplicity, we consider only the situation for TE modes; thus, W e ≈ W MMI . The general matrix theory of self-imaging in MMI couplers with single-mode input and output waveguides is used, 18,25 and the multimode waveguide is split into five subsections with the same length L s , as shown in Fig. 2(a).…”

Section: Device Structure and Basic Mechanismsmentioning

confidence: 99%

Optimization of a thermally tuned silicon-based reconfigurable optical power splitter with thermal isolations

Han

2017

Opt. Eng

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Abstract. In this paper, a thermally tuned silicon-based three-channel reconfigurable multimode interference (MMI) optical power splitter with four optimized thermal isolations is proposed. Specific and flexible reconfigurable functions (1 × 1, 1 × 2, and 1 × 3 MMI splitters) can be achieved by thermally tuning the heaters. By using a beam propagation method, the optimum geometry of the heaters, desired refractive index changes, and phase shifts of the MMI splitter are calculated at first. The temperature distributions of the devices without and with the thermal isolations are then analyzed by using the finite element method. Thermal crosstalk between adjacent heaters is observed and the influence of the thermal isolation geometry on the thermal crosstalk is examined subsequently. The geometry of the thermal isolations is optimized based on the trade-off between the thermal tuning efficiency and optical output characteristics. Finally, satisfactory improvements with the proposed structure are demonstrated with high-thermal efficiency (the maximum power dissipation decreases reach 43.7% and 55.2% for 1 × 1 and 1 × 2 MMI splitters, respectively) and good optical output quality (the maximum excess losses are as low as 0.365, 0.388, and 0.272 dB for 1 × 1, 1 × 2, and 1 × 3 MMI splitters, respectively; the crosstalk is less than −21.27 and −15.54 dB for 1 × 1 and 1 × 2 MMI splitters, respectively). © The Authors. Published by SPIE under a Creative Commons Attribution 3.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.

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“…, can be calculated for any N [18]. This matrix applies for coherent beams as well as for a single photon.…”

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confidence: 99%

“…4) versus the phase φ, for three different relative propagation lengths at which 2×2 BSs are implemented [see Fig. 1 2,1 is a 15:85 BS implemented for ζ = 1/8, and that for q = 8 (ζ = 1), full imaging is obtained [17,18]. The state ψ 0 2 is invariant only under reflection, and thus returns to its initial form only when full reflection occurs -once every four applications of T (1) 2,1 (e.g.…”

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confidence: 99%

Two-Photon Path-Entangled States in Multimode Waveguides

2012

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We experimentally show that two-photon path-entangled states can be coherently manipulated by multi-mode interference in multi-mode waveguides. By measuring the output two-photon spatial correlation function versus the phase of the input state, we show that multi-mode waveguides perform as nearly-ideal multi-port beam splitters at the quantum level, creating a large variety of entangled and separable multi-path two-photon states.PACS numbers: 42.50. Dv, 03.67.Bg, 42.79.Gn Quantum states of photons distributed between several optical paths play the central role in linear optical quantum computation [1]. In particular, entangled states, where no decomposition into a product of either single-path or single-photon states exists, are of great importance due to their non-local nature [2,3]. Entangled photons states are generated either by non-linear processes in crystals [4], by cascaded emission of single quantum emitters [5], or by quantum interference of nonclassical light on a beam splitter [6,7].Quantum interference in arrays of beam-splitters (BSs) is used in many linear optical quantum computation schemes to create and manipulate multi-photon multipath states [8][9][10]. The simplest example is the HongOu-Mandel (HOM) interference [11]. In this fundamental effect, two identical photons input each on a different port of a 50:50 BS, cannot exit in two different ports due to destructive interference of the two possible paths. Therefore, they always exit bunched together on either one of the output ports, in an entangled state. A major obstacle on the way to the implementation of quantum optical circuits is the large number of BSs required, and the increasing complication of their alignment. One way to overcome this problem is through miniaturization of the optical circuites. Indeed, quantum interference has been recently demonstrated in integrated optical circuites composed of evanescently coupled singlemode waveguides embedded in solids [12][13][14]. A conceptually different route towards robust implementation of quantum optical circuites may come in the form of multi-mode interference (MMI) devices [15]. These compact replacements for BS arrays, usually based on planar multi-mode waveguides (MMWs), are already used extensively in modern classical optical communication networks. They have also been proposed to be useful for creation and detection of multi-photon states [10], as they naturally implement Bell multiport BSs [8]. A step towards their use in quantum networks was recently made with the demonstration of HOM interference of two separated photons in an MMW [16]. The question still remains, however, whether entangled states, which unlike separated photons, carry relative phase information, can be coherently manipulated by MMWs.Here we experimentally show that the answer to this question is positive. We utilize MMI in a two-mirror, tunable planar MMW [17] to implement multi-port BS arrays of up to 5 input and 5 output ports, and explore the propagation of non-classical, path-entangled two-photon states t...

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General matrix theory of self-imaging in multimode interference (MMI) couplers

Cited by 82 publications

References 7 publications

A Mode MUX/DEMUX for Multicore Fibers With 2D Core Arrays

A Mode MUX/DEMUX for Multicore Fibers With 2D Core Arrays

Optimization of a thermally tuned silicon-based reconfigurable optical power splitter with thermal isolations

Two-Photon Path-Entangled States in Multimode Waveguides

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