Compact spatial multiplexers for mode division multiplexing

Chen, Haoshuo; Uden, Roy van; Okonkwo, Chigo; Koonen, Ton

doi:10.1364/oe.22.031582

Cited by 51 publications

(26 citation statements)

References 31 publications

(35 reference statements)

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“…Solutions of A 1 (z) and B + 0 (z) Noticing that 1 ≈ ς * 1 and following a similar argument to what we did in the last subsection, it can be checked that the solutions of the two equations (16) and (18) can be written as:…”

Section: Solution Of the Coupled-mode Equationsmentioning

confidence: 71%

“…From the last section, we have four coupled-mode equations as given in (12), (16), (18), and (21). The coupling coefficients ζ ν m , κ ν m , ς m , ι ν , and m are given in (13), (14), (17), (19), and (20), respectively.…”

Section: Solution Of the Coupled-mode Equationsmentioning

confidence: 99%

“…Solutions of A 2 (z) and B − 0 (z) 1) Correction to the Phase Matching Condition: The set of equations (12), (16), (18), and (21) suggests the following corrections to the phase matching conditions:…”

Section: Solution Of the Coupled-mode Equationsmentioning

confidence: 99%

See 2 more Smart Citations

Bi-Directional Coupler as a Mode-Division Multiplexer/Demultiplexer

Shalaby

2016

J. Lightwave Technol.

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A bi-directional coupler supported with Bragg grating is proposed as a mode-division multiplexer/demultiplexer. The structure can demultiplex 3 modes with only two waveguides and a Bragg grating. The input waveguide is multimode, while the output waveguide is single-mode. Both first-and second order modes of the input waveguide are coupled to the output waveguide, propagating at opposite directions, while the fundamental mode is kept in the input waveguide. A theoretical analysis of the proposed demultiplexer is developed based on the perturbative mode-coupled theory. The insertion losses of both first-and second order modes are derived under suitable phase-matched conditions. Expressions of the insertion losses are obtained for simple slab-waveguides coupler. Numerical results of the proposed demultiplexer are presented for the slabwaveguides coupler under different design parameters. Furthermore, the wavelength dependence of the device is addressed under mismatching conditions and a Lorentzian model of the Silicon material. In addition, FDTD simulation of proposed demultiplexer is performed to prove the validity of the proposed concept. Return loss due to reflection to the source is taken into consideration in the simulation in addition to the device wavelength dependence.

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Section: Solution Of the Coupled-mode Equationsmentioning

confidence: 71%

Section: Solution Of the Coupled-mode Equationsmentioning

confidence: 99%

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Bi-Directional Coupler as a Mode-Division Multiplexer/Demultiplexer

Shalaby

2016

J. Lightwave Technol.

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“…In photonics, too, rapid advances in 2D photonic integrated circuits (PICs) have also motivated us to coin a term 'photonic Moore's Law' 9,10 . More recently, 3D photonic integration has emerged as very important steps towards bringing new functionality and a higher degrees of integration to microsystems [11][12][13][14][15][16][17][18][19][20] . For instance, space division multiplexing (SDM) based on 3D photonic integration overcomes limitations imposed on 2D photonics in handling the spatial degree of freedom and polarization dependence resulting from the fact that all waveguides must lie within the same 2D plane.…”

Section: Introduction: Why Photonics? Why Heterogeneous Integration? mentioning

confidence: 99%

Heterogeneous 2D/3D photonic integrated microsystems

2016

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The continuing trend of exponential growth in data communications and processing are driving the need for large-scale heterogeneous integration. Similar to the trend we have observed in electronic integrated circuit development, we are witnessing a growing trend in 3D photonic integrated circuits (PICs) development in addition to that in 2D PICs. There are two main methods for fabricating 3D PICs. The first method, which utilizes ultrafast laser inscription (ULI), offers freeform shaping of waveguides in arbitrary contours and formations. The second method, which utilizes multilayer stacking and coupling of planar PICs, exploits relatively mature 2D PIC fabrication processes applied to each layer sequentially. Both the fabrication methods for 3D PICs have advantages and disadvantages such that certain applications may favor one method over the other. However, a joining of 2D PICs with 3D PICs can help develop integrated microsystems with new functionalities such as non-mechanical beam steering, spacedivision multiplexing (SDM), programmable arbitrary beam shaping, and photonic signal processing. We discuss examples of 3D PICs and 2D/3D integrated PICs in two applications: SDM via orbital-angular-momentum (OAM) multiplexing/demultiplexing and optical beam steering using optical phased arrays. Although a 2D PIC by itself can function as an OAM multiplexer or demultiplexer, it has limitations in supporting both polarizations. Alternatively, a 3D PIC fabricated by ULI can easily support both polarizations with low propagation loss. A combination of a 3D PIC and a 2D PIC designed and fabricated for OAM applications has successfully multiplexed and demultiplexed 15 OAM states to demonstrate polarization-diversified SDM coherent optical communications using multiple OAM states. Coherent excitation of multi-ring OAM states can allow highly scalable SDM utilizing Laguerre-Gaussian modes or linearly polarized (LP) modes. The preliminary fabrication of multi-ring OAM multiplexers and demultiplexers using the multilayer 3D PIC method and the ULI 3D PIC method has also been pursued. Large-scale (for example, 16 × 16 optical phased array) 3D PICs fabricated with the ULI technique have been demonstrated. Through these examples, we show that heterogeneous 2D/3D photonic integration retains the advantages of 2D PICs and 3D waveguides, which can potentially benefit many other applications.

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“…The excitation and separation of spatial modes is essential in SDM [26]. In this letter, we propose a mode selective slab waveguide design by using a HMM as a cladding material.…”

mentioning

confidence: 99%

Spatial mode-selective waveguide with hyperbolic cladding

Tang¹,

Xi²,

Xu³

et al. 2016

Opt. Lett.

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Hyperbolic Meta-Materials (HMMs) are anisotropic materials with permittivity tensor that has both positive and negative eigenvalues. Here we report that by using a type II HMM as cladding material, a waveguide which only supports higher order modes can be achieved, while the lower order modes become leaky and are absorbed in the HMM cladding. This counter-intuitive property can lead to novel application in optical communication and photonic integrated circuit. The loss in our HMM-Insulator-HMM (HIH) waveguide is smaller than that of similar guided mode in a Metal-Insulator-Metal (MIM) waveguide. c 2018 Optical Society of America Meta-materials are structures engineered at the subwavelength scale to exhibit specific electromagnetic properties. The development of nanofabrication techniques allows to make these structures and to realize new properties that are unobtainable with conventional media. Among the varieties of meta-materials, Hyperbolic Meta-Materials (HMMs) have gained tremendous attention. Their exotic hyperbolic dispersion property is the key to numerous emerging nano-photonics applications, including sub-diffraction-limit imaging [1][2][3][4][5][6][7], Purcell factor enhancement [8][9][10][11][12][13], sensing [14][15][16], and waveguide engineering [17][18][19][20][21][22][23][24]. Here we report a new application of HMM for waveguide spatial mode engineering, which brings up new possibility in Spatial-Division Multiplexing (SDM).SDM utilizes the last unexplored physical dimension, space, to further increase the data carrying capacity in optical communication [25]. The excitation and separation of spatial modes is essential in SDM [26]. In this letter, we propose a mode selective slab waveguide design by using a HMM as a cladding material. With a cladding consisting of HMM, the lower order modes with larger propagation constant become propagating wave in the HMM cladding material, such that they are turned into leaky modes. At the same time, higher order modes with smaller propagation constant are evanescent wave in the HMM cladding and remain guided in the core. Also by choosing the right parameter for the cladding one can design a 'single mode' waveguide only guiding one specific higher order mode, which can be applied as mode launcher or mode receiver in a SDM system. Compared to conventional spatial multiplexing techniques based on interference [27] or holography [28], our approach merely modifies the waveguide property and requires no extra optical component, which is more compact and efficient.We only consider transverse magnetic (TM) wave (E y = 0) because the hyperbolic cladding only has the desired property for this state of polarization. The TM wave is propagating in a slab waveguide core towards the positive z direction (Fig. 1a). The core thickness is 2a. The magnetic field of the mode is independent of the y-coordinate, and has the form H y = H(x) exp(iβ m z), where β m = k z,m is the propagation constant of the m th order mode along the z-direction, which satisfies the equation, where k...

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Compact spatial multiplexers for mode division multiplexing

Cited by 51 publications

References 31 publications

Bi-Directional Coupler as a Mode-Division Multiplexer/Demultiplexer

Bi-Directional Coupler as a Mode-Division Multiplexer/Demultiplexer

Heterogeneous 2D/3D photonic integrated microsystems

Spatial mode-selective waveguide with hyperbolic cladding

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