Nonreciprocal Phase Shift Research Articles

Magneto-Photonic Crystal Slab Waveguides With Lower-Refractive-Index-Silica Claddings

This letter proposes a new form of magneto-photonic crystal slab waveguides including nanoporous SiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> , with an extremely low refractive index, as the cladding material. These structures allow us to achieve physical strength and to render unnecessary holes extending to cladding layers. Our letter investigates the significance of the waveguide geometry for nonreciprocal phase shifts and losses, using a three-dimensional finite-element method with periodic boundary conditions. The guided modes exhibit small losses well below the light line and high nonreciprocal phase shifts with appropriate parameters, according to the calculations in this letter

Wideband operation of Mach-Zehnder interferomertic magneto-optical isolator using phase adjustment

A wideband operation of a magneto-optical isolator is demonstrated. The isolator is based on a Mach-Zehnder interferometer employing nonreciprocal phase shift. The wideband operation is achieved by adjusting a reciprocal phase difference in the interferometer. We designed and fabricated a wideband isolator with a magneto-optic garnet waveguide. The isolation ratio of 15-25dB was obtained in a wavelength range from 1530nm to 1640nm.

Nonreciprocal microresonators for the miniaturization of optical waveguide isolators

By introducing nonreciprocal phase shifts into microresonators, we propose new designs for the miniaturization of optical waveguide isolators and circulators. We present detailed design procedures, and numerically demonstrate the operation of these magneto-optical devices. The device sizes can be reduced down to several tens of micrometers. The nonreciprocal function of these devices is due to nonreciprocal resonance shifts. Next, the operation bandwidth can be expanded by increasing the number of resonators (the filter order). This is demonstrated by comparing the characteristics of a single-resonator structure with those of a three-resonator structure. This paper furthermore presents the nonreciprocal characteristics of three-dimensional resonators with finite heights, leading to a guideline for the design of nonreciprocal optical circuits. This involves a demonstration of how the resonators with selected parameters are practical for miniaturized nonreciprocal circuits.

Optical isolating action in surface plasmon polaritons

The authors consider propagation of a plasmon polariton on the interface between a metal and a magneto-optical material and show that in presence of transverse magnetic field a strong nonreciprocal phase shift results. This phenomenon can be used to achieve optical isolation action in short nanoplasmonic guides with low insertion loss.

Wideband design of nonreciprocal phase shift magneto-optical isolators using phase adjustment in Mach-Zehnder interferometers

A wideband design is proposed for nonreciprocal phase shift magneto-optical isolators based on Mach-Zehnder interferometers. The wavelength dependence of nonreciprocal phase difference between the backward waves propagating in two interferometer arms is compensated for by that of reciprocal phase difference. This is realized by introducing an appropriate phase bias in one of interferometer arms. Two design examples are presented with a backward loss of >30 dB in the wavelength range of 1.40-1.63 microm for a magnetic garnet waveguide isolator and of 1.485-1.630 microm for a Si-wire waveguide isolator.

Interferometric optical isolator with Si guiding layer fabricated by wafer bonding

An interferometric optical isolator, with a Si guiding layer, employing a nonreciprocal phase shift was studied. The optical isolator was comprised of a magneto-optic waveguide with a magnetic garnet/Si/SiO 2 structure, which was fabricated by wafer bonding technique. The nonreciprocal phase shift in the magneto-optic waveguide with the Si guiding layer was calculated at a wavelength of 1.55 μm. Several kinds of layer structures in the magneto-optic waveguide were discussed.

Finite Element Analysis of Millimeter and Sub-Millimeter Wave Gyroelectric Waveguide Components

Gallium arsenide (GaAs) and indium antimonide (InSb) are two candidate semiconductor materials for supporting nonreciprocal behavior at millimeter wave and sub-millimeter wave frequencies. Each material is characterized as a function of bias field/frequency and different operating regions are identified either side of the extraordinary wave resonance. An eigenvalue finite element formulation is developed to calculate the complex propagation constant for general gyroelectric waveguide structures. The solver is used to investigate nonreciprocal phase shift and attenuation in a transversely magnetized, semiconductor slab loaded waveguide in the various operating regions. Several potential regions of isolation and differential phase shift have been identified for exploitation in the millimeter wave range for GaAs and in the sub-millimeter wave range for InSb.

Coupling Characteristics of Three-Guide Tapered Coupler for Optical Isolator with Si Guiding Layer

An optical isolator employing a nonreciprocal phase shift is composed of a three-guide tapered coupler. The coupling characteristics of the three-guide tapered coupler for an integrated optical isolator with a Si guiding layer are demonstrated.

Magneto-optical phase modulation in integrated Mach–Zehnder interferometric sensors

The integrated Mach–Zehnder interferometric biosensors are one of the most promising optical biosensors due to their extreme sensitivity and possibility of integration in a lab-on-a-chip. However, the periodic response of the interferometric devices complicates the interpretation of experimental results due to the ambiguity and fading of the signal. To overcome these problems we present a phase modulation system based on the introduction of a periodic phase shift in the reference arm of the interferometers and the Fourier analysis of the output signal. This system allows the direct and unambiguous detection of the phase changes induced by the biosensing measurement. As phase modulation mechanism, we propose and theoretically analyze two different magneto-optic (MO) methods compatible with the standard microelectronic processes. The phase modulators are based on silicon-on-insulator (SOI) waveguides and yttrium iron garnets (YIG) as magnetic material. The first one exploits the non-reciprocal phase shifts induced in the TM guided modes when the orientation of the magnetization of an YIG layer is rotated within the plane of the layer. On the other hand, the MO phase modulation can also rely on the birefringence induced in magnetic liquids under an external magnetic field. We demonstrate that the MO phase modulation is compatible with SOI waveguides showing very high surface sensitivity in the biosensing measurements. In addition, the MO phase modulation can be achieved by using MO interaction lengths of only a few millimetres, facilitating the integration within the interferometric biosensors.

Interferometric Optical Isolator with TiO2/Magnetic Garnet Waveguide Operated in Unidirectional Magnetic Field

An optical isolator with a TiO2/magnetic garnet waveguide obtained using a nonreciprocal phase shift was studied. The optical isolator can be operated in a unidirectional magnetic field owing to an interferometer with distinct layer structures.

Proposed Configuration of Optical Isolator with TiO2/Magnetic Garnet Waveguide

An optical isolator with a TiO2/magnetic garnet waveguide obtained using nonreciprocal phase shift was proposed. The magnetooptic waveguide had an air/TiO2/magnetic garnet structure in which magnetic garnet was used as a lower cladding layer. Nonreciprocal phase shift in the magnetooptic waveguide was calculated at a wavelength of 1.55 µm. A magnetooptic waveguide with a TiO2/magnetic garnet guiding layer was also investigated. The required propagation distance for isolator operation was less than that of the optical isolator with the air/TiO2/magnetic garnet waveguide.

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A novel interferometric isolator has been proposed and designed to fabrticate waveguide magnetooptic isolator operating at a wavelength of . The device consists of MMI (multimode interference) couplers and has a magnetooptic guiding layer with different layer structure in arms of the inteferometer. The layer structures in the arms of inteferometer are and , respectively. This configuration give rise to different nonreciprocal phase shift. In consequence, the isolator operates under a unidirectional magnetic field. The optimized structure of the isolator was determined by a 3D beam propagation method.낻?⨀Ȁ낻?⨀킻?⨀Ѐ킻?⨀삻?⨀ࠀ삻?⨀𾶖⨀Ȁ𾶖⨀ᢼ?⨀Ȁᢼ?⨀ゼ?⨀ゼ?⨀䢼?⨀✀䢼?⨀낼?⨀ᔀ낼?⨀ᢽ?⨀Ȁᢽ?⨀肽?⨀Ȁ肽?⨀?⨀Ȁ?⨀룏?⨀Ā룏?⨀ꂐ?⨀Ѐꂐ?⨀傾?⨀܀傾?⨀墾?⨀Ԁ墾?⨀炾?⨀Ȁ炾?⨀碾?⨀Ȁ碾?⨀棏?⨀Ȁ棏?⨀壏?⨀Ā壏?⨀䂐?⨀؀䂐?⨀䃏?⨀Ā䃏?⨀惏?⨀ࠀ惏?⨀墐?⨀Ȁ墐?⨀ꃏ?⨀Āꃏ?⨀⢐?⨀Ȁ⢐?⨀႐?⨀Ȁ႐?⨀?⨀Ȁ?⨀?⨀Ȁ?⨀꣏?⨀܀꣏?⨀냏?⨀Ȁ냏?⨀

Three-dimensional finite element analysis of nonreciprocal phase shifts in magneto-photonic crystal waveguides

This report presents the first three-dimensional characterization of nonreciprocal phase shifts in magneto-photonic crystal (MPC) slab waveguides. We model MPC waveguides using a three-dimensional finite element method with curvilinear tetrahedral edge elements. This study investigates the dependence of nonreciprocal phase shifts on the width and the thickness of the waveguides, and we investigate the dependence of losses on the air hole depth, leading to a guideline for the design of optical isolators. Simulations show that waveguides with reduced width and deep air holes exhibit high nonreciprocal phase shifts and low losses. The study also shows that, compared with two-dimensional calculations, nonreciprocal phase shifts express key similarities, although the frequencies of the guided modes shift.

Interferometric optical isolator employing a nonreciprocal phase shift operated in a unidirectional magnetic field.

An interferometric optical isolator that employs a nonreciprocal phase shift was studied. The optical isolator consisted of an interferometer with distinct layer structures. A traveling light wave underwent distinct nonreciprocal phase shifts such that the optical isolator could be operated in a unidirectional magnetic field. The optical isolator, in which the waveguide had a HfO2 cladding layer in one of the arms, was designed at a wavelength of 1.55 microm. The propagation distance of the nonreciprocal phase shifter required for the isolator's operation was less than 1.5 mm. The device's total length was less than 2 mm. An optical isolator with distinct layer structures was fabricated and evaluated. An isolation ratio of approximately 9.9 dB was obtained in the unidirectional magnetic field.

Calculation of Nonreciprocal Phase Shift in Magnetooptic Waveguide with Si Guiding Layer

A nonreciprocal phase shift in a magnetooptic waveguide with a Si guiding layer is discussed. The magnetooptic waveguide was installed in an optical isolator employing the nonreciprocal phase shift. The magnetooptic waveguide had a magnetic garnet/Si/SiO2 structure, which was realized by wafer bonding technique. The nonreciprocal phase shift in the magnetooptic waveguide with the Si guiding layer was calculated at a wavelength of 1.55 µm. A required thickness of the magnetic garnet cladding layer was obtained by calculating the nonreciprocal phase shift. An optical isolator employing the nonreciprocal phase shift, which could be operated under unidirectional magnetic field, was proposed by contriving the layer structures in the interferometer.

Development of a Millimeter-Wave Ferrite-Filled Antisymmetrically Biased Rectangular Waveguide Phase Shifter Embedded in Low-Temperature Cofired Ceramic

The theory of a new ferrite-filled rectangular waveguide phase shifter is presented, showing that the device offers more than twice the maximum phase shift of a classical dual-slab ferrite-loaded waveguide phase shifter. The complete analytical field derivation of the new phase shifter is presented. The prototype 36-GHz phase shifter has been completely embedded in an uncharacterized experimental low-temperature cofired ferrite ceramic material, essentially becoming an integral part of a chip package. The fabricated prototype is only 3.5-cm long, 5-mm wide, and 1-mm high. Preliminary measurements of the nonoptimized prototype reveal a controllable, nonreciprocal phase shift of 52.8/spl deg/ at 36 GHz for a bias current of 500 mA, and an insertion loss of approximately 3.6 dB, including transition loss. This paper marks the first time that a ferrite waveguide phase shifter has been realized as a lightweight, compact, and rugged module that can be easily mass produced at low cost. Since it is embedded in a package, the phase shifter can be readily integrated with other active and passive system components that would ideally be contained within the same package.

Magneto-optical nonreciprocal phase shift in garnet/silicon-on-insulator waveguides.

We demonstrate the integration of a single-crystal magneto-optical film onto thin silicon-on-insulator (SOI) waveguides by use of direct wafer bonding. Simulations show that the high confinement and asymmetric structure of SOI allows an enhancement of approximately 3x over the nonreciprocal phase shift achieved in previous designs; this value is confirmed by our measurements. Our structure will allow compact magneto-optical nonreciprocal devices, such as isolators, integrated on a silicon waveguiding platform.

Enhancement of Magneto Optic Effect in Optical Isolator with GaInAsP Guiding Layer by Selective Oxidation of AlInAs

A selectively oxidized AlInAs layer with low refractive index can enhance the magneto optic effect and improve the characteristics of optical nonreciprocal devices. We successfully fabricated an optical waveguide with an AlInAs oxide lower cladding layer. The refractive index of the AlInAs oxide was determined to be 2.45 at λ=1.55 µm. The optical nonreciprocal phase shift of this waveguide was more than twelvefold than that of the magneto optic waveguide with an InP cladding layer.

Waveguide Optical Isolators Fabricated by Wafer Bonding

ABSTRACTWafer bonding of a magnetooptic garnet crystal to III-V compound semiconductor and LiNbO3 is discussed for the application to waveguide optical isolators. Two types of waveguide isolators, an interferometric isolator and a semileaky isolator, are discussed. The interferometric isolator uses nonreciprocal phase shift and is composed of the GaInAsP guiding layer. The isolator has the advantage of integratability with optical active devices. The semileaky isolator composed of a magnetooptic garnet guiding and LiNbO3 upper cladding layer has the advantages of large fabrication tolerance and wide operating wavelength range. The performance of isolators is also demonstrated.

Mode-matching analysis of H-plane ferrite-loaded rectangular waveguide discontinuities

The full set of eigenmodes existing in a ferrite-slab-loaded rectangular waveguide is first obtained and then used to compute the scattering matrix of a junction between an air-filled rectangular waveguide and an H-plane ferrite-slab-loaded rectangular waveguide by using the mode-matching method. Numerical results for the scattering parameters of the H-plane waveguide discontinuity are compared to experimental data and those obtained by Ansoft's HFSS. Good agreement is observed. To demonstrate the usefulness of this structure, a computer-optimized 90° nonreciprocal phase shifter is designed using an H-plane ferrite-slab-loaded waveguide. With only one-step impedance matching sections at both ends of the ferrite slab, a compact design is achieved to have 2° phase error and less than −30 dB return loss over about 5% bandwidth. © 2003 Wiley Periodicals, Inc. Int J RF and Microwave CAE 13: 259–268, 2003.