Monolithic On-chip Magneto-optical Isolator with 3 dB Insertion Loss and 40 dB Isolation Ratio

Du, Qingyang; Wang, Chuangtang; Zhang, Yifei; Zhang, Yan; Fakhrul, Takian; Zhang, Wei; Goncalves, Claudia; Blanco, Cesar; Richardson, Kathleen; Deng, Longjiang; Ross, Caroline A.; Bi, Lei; Hu, Juejun

doi:10.1021/acsphotonics.8b01257

Cited by 68 publications

(40 citation statements)

References 55 publications

(95 reference statements)

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“…However, the integration of garnets on a Si (or other semiconductor) platform is challenging due to the incompatible lattice parameters and the thermal expansion mismatch between garnets and common semiconductor substrates . Moreover, crystallization of the garnet phase usually requires a high thermal budget.…”

Section: Introductionmentioning

confidence: 99%

“…Considerable work has been done on growth of garnet films on semiconductors to enable demonstrations of isolators and modulators . The first monolithically integrated optical isolator used 80 nm thick Ce:YIG which was grown by pulsed laser deposition (PLD) on a pre‐annealed 20 nm thick YIG seed layer to induce crystallization of the Ce:YIG.…”

Section: Introductionmentioning

confidence: 99%

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Magneto‐Optical Bi:YIG Films with High Figure of Merit for Nonreciprocal Photonics

Fakhrul

Tazlaru

Beran

et al. 2019

Advanced Optical Materials

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lator devices is commonly a MO iron garnet material, in particular yttrium iron garnet (YIG, Y 3 Fe 5 O 12 ) with substituents such as Ce or Bi to increase the MO performance. [5][6][7][8][9][10][11][12][13][14][15] However, the integration of garnets on a Si (or other semiconductor) platform is challenging due to the incompatible lattice parameters and the thermal expansion mismatch between garnets and common semiconductor substrates. [6][7][8][9][10][11][12][13][14][15][16] Moreover, crystallization of the garnet phase usually requires a high thermal budget. Garnets formed on semiconductor substrates are polycrystalline and exhibit higher optical absorption than single crystal films. Furthermore, impurity phases such as YFeO 3 , Fe 2 O 3 , and Bi 2 O 3 can form during the crystallization process, [17] which contributes to optical loss. These factors result in inferior optical performance of polycrystalline MO garnet films compared to the bulk garnet material, and a lower figure of merit (FoM), defined as the ratio of the Faraday rotation to the absorption coefficient per length of the material.Considerable work has been done on growth of garnet films on semiconductors to enable demonstrations of isolators and modulators. [6][7][8][9][10][11][12][13][14][15][16] The first monolithically integrated optical isolator [6] used 80 nm thick Ce:YIG which was grown by pulsed laser deposition (PLD) on a pre-annealed 20 nm thick YIG seed layer to induce crystallization of the Ce:YIG. A simplified PLD process was introduced by Sun et al. [11] where the YIG seed layer was placed on top of the MO garnet and both layers were crystallized simultaneously by rapid thermal annealing (RTA). This top-seedlayer process places the MO garnet in direct contact with the underlying Si waveguide, maximizing the coupling of light from the waveguide to the MO cladding, but it has only been applied to Ce:YIG. Recently rare-earth garnets have been developed that crystallize on Si and quartz without a seed layer, including sputter-deposited terbium iron garnet (TIG) and Bi-doped TIG (Bi:TIG). [18,19] Growth of MO materials on the sidewall of the waveguide can enable a wider range of device designs, including isolators for transverse electric (TE) polarization. Integrated semiconductor lasers emit TE-polarized light, and TE mode isolation using NRPS requires placement of the MO material on the sidewall of the waveguide to break left-right symmetry. [18,20,21] However, the NRPS-based integrated optical isolators that have been experimentally demonstrated are made with the MO material on the top or bottom surface of the waveguide, which isolates only the transverse magnetic (TM) polarization. [6][7][8][11][12][13][14] It is therefore essential to establish deposition conditions that yield Thin film magneto-optical (MO) materials are enablers for integrated nonreciprocal photonic devices such as isolators and circulators. Films of polycrystalline bismuth-substituted yttrium iron garnet (Bi:YIG) have been grown on silicon substrates and waveguide d...

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Magneto‐Optical Bi:YIG Films with High Figure of Merit for Nonreciprocal Photonics

Fakhrul

Tazlaru

Beran

et al. 2019

Advanced Optical Materials

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“…The isolator design is depicted in Figure 1a (perspective view) and 1b (cross-section) 42 . The basic building block of the isolator is a nonreciprocal magneto-optical resonator comprising striploaded waveguides on a deposited CexY3-xFe5O12 (Ce:YIG) film.…”

Section: High-performance Tm Ring Isolatormentioning

confidence: 99%

“…The process flow to fabricate the isolator structure is shown in Figure 1d. 2indicate optical paths used to interrogate the device in forward and backward directions, respectively; (b) transmission spectra of the isolator: inset shows the same spectra over several free spectral ranges of the resonator; (c) resonant peak wavelengths of the device repeatedly measured for five consecutive times; (d) spectral dispersion of the nonreciprocal resonant wavelength shift measured in the isolator 42 . Figure 2a illustrates a schematic diagram of the isolator characterization setup.…”

Section: High-performance Tm Ring Isolatormentioning

confidence: 99%

“…(a) Tilted-view and (b) cross-sectional schematic of the new isolator design; (c) nonreciprocal phase shift and waveguide figure of merit computed as functions of the strip-loaded waveguide core refractive index: the insets are modal profiles of strip-loaded waveguides when the core material is chosen as silicon nitride (n = 2.0), GeSbSe glass (n = 2.7), and amorphous silicon (n = 3.6), where the scale bars correspond to 500 nm; (d) fabrication process for the isolator device42 .…”

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confidence: 99%

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Filling in the missing link: monolithic optical isolators on silicon with high performance, broadband operation, and polarization diversity

Zhang

et al. 2020

Photonic and Phononic Properties of Engineered Nanostructures X

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On-chip optical isolators constitute an essential building block for photonic integrated circuits. Monolithic magnetooptical isolators on silicon, while featuring unique benefits such as scalable integration and processing, fully passive operation, large dynamic range, and simple device architecture, had been limited by their far inferior performances compared to their bulk counterparts. Here we discuss our recent work combining garnet material development and isolator device design innovation, which leads to a monolithic optical isolator with an unprecedented low insertion loss of 3 dB and an isolation ratio up to 40 dB. To further overcome the bandwidth and polarization limitations, we demonstrated broadband optical isolators capable of operating for both TM and TE modes. These results open up exciting opportunities for scalable integration of nonreciprocal optical devices with chip-scale photonic circuits.

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Spoof Localized Surface Plasmon Enhanced Isolation and Circulation

Zhang

Wang

et al. 2022

Adv Materials Technologies

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crosstalk between parallel transmission channels and increase the signal integrity in circuits with dense wiring. [5] Moreover, the dispersion properties of SSPPs can be engineered by tuning the structures of the surface patterning or the bias voltages/currents of the integrated varactor diodes/positive-intrinsic-negative (PIN) diodes, providing flexibility in the design of devices with multiple functionalities or working frequency bands. [6][7][8][9] The metamaterial approach can also be used to design localized surface plasmons (LSPs) at low frequencies by making corrugations on closed metal surfaces. Spoof LSPs(SLSP) resonators with straight or spiral corrugations have been demonstrated to support multiple resonance modes [10,11] and applied in the design of sensors, [12,13] filters, [14,15] etc. Compared with straight corrugation structures, because the spiral structure accommodates longer corrugations within the same area, the resonance frequency is reduced, giving rise to devices with deep-subwavelength sizes. [16] The isolator and circulator are fundamental EM devices that allow nonreciprocal signal routing in photonic and microwave circuits and are widely used in radar, communication, and detection systems. Because the isolator/circulator permits the transmission of EM waves in only one direction, the transfer function can be modified as desired, and the detrimental feedback between different components in the circuit due to unwanted reflections is suppressed. Various mechanisms have been leveraged to achieve such nonreciprocal propagation, including magneto-optical effects, [17][18][19] nonlinearity, [20,21] time modulation, [22][23][24][25][26] near-zero-index metamaterials, [27] topologically protected edge states in photonic crystals, [28] and mode coupling between photonic crystal and resonant system. [29] Among these, the magneto-optical effect is the most commonly adopted, where the symmetry of the electric permittivity tensor is broken by applying an external magnetic field to a ferromagnetic medium. Recently, this mechanism has also been used for designing SSPP isolators and circulators. [30,31] However, these SSPP isolators and circulators are composed of multiple layers of dielectric substrates, SSPP waveguides, and bulky ferrite slabs. Furthermore, the proposed devices usually have only a single operating band.Herein, we report experimental demonstrations of an isolator and a circulator for SSPPs, which are based on the interaction between magneto-SLSP resonator(s) and SSPP waveguide(s). The deep-subwavelength spiral-shaped SLSP resonator coated with the magneto-optical material under a static magnetic field allows surface waves to circulate in A miniaturized spoof plasmonic isolator comprising a deep-subwavelength spoof localized surface plasmon (SLSP) resonator coupled with an ultrathin spoof surface plasmon polariton waveguide is proposed and experimentally demonstrated. The SLSP resonator coated with a magneto-optical material can enhance the isolation property, allowing for multifrequency...

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Monolithic On-chip Magneto-optical Isolator with 3 dB Insertion Loss and 40 dB Isolation Ratio

Cited by 68 publications

References 55 publications

Magneto‐Optical Bi:YIG Films with High Figure of Merit for Nonreciprocal Photonics

Magneto‐Optical Bi:YIG Films with High Figure of Merit for Nonreciprocal Photonics

Filling in the missing link: monolithic optical isolators on silicon with high performance, broadband operation, and polarization diversity

Spoof Localized Surface Plasmon Enhanced Isolation and Circulation

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