Opto-Electronic Engineering, Volume. 52, Issue 2, 240285-1(2025)
Research progress on on-chip integrated optical isolators
Figures & Tables(20)
![On-chip integrated optical isolators based on different effects[12,15,18,21]](/Images/icon/loading.gif){kind=icon}
Fig. 2. Single-mode waveguide two-port isolator and its scattering matrix
Fig. 3. Diagram of traditional bulk magneto-optical isolator device
Fig. 4. Wafer-level indirect bonding for the preparation of MO-MZI isolator[38-39]. (a) Schematic top view of the optical isolator composed of a MZI covered with Ce: YIG; (b) Cross-sectional view; (c) Transmission spectra for forward and backward transmission; (d) Schematic of the structure after the addition of PR; (e) Transmission spectra under an applied magnetic field
Fig. 5. Wafer-level direct bonding for the fabrication of MO-MZI isolator [7,31]. (a) Schematic diagram of an SOI waveguide optical isolator based on MZI; (b) Microscope image of the fabricated MZI silicon waveguide optical isolator; (c) Transmission spectra for forward and backward transmission; (d) Schematic diagram of the optical isolator integrated with a TE-TM mode converter; (e) Microscope image of the integrated optical isolator on the Si platform; (f) Transmittance between port 1 and port 2 of the integrated optical isolator
Fig. 6. MO-MZI isolator fabricated by deposition technology [32,40]. Optical microscope and scanning electron microscope (SEM) images of (a) TM and (b) TE isolators, respectively, with a scale bar of 100 μm; Transmission spectra of (c) TM and (d) TE mode isolators, respectively; (e) SEM image of the cross-section of the fabricated Si3N4/MO waveguide; (f) Simulation of the Ey field distribution of the fundamental TM mode in the Si3N4/MO waveguide; Transmission spectra of (g) TM and (h) TE mode isolators, respectively
Fig. 7. MO-MR isolator[8,33]. (a) Working principle of MO-MR optical isolation; (b) Schematic diagram of the non-reciprocal optical resonator structure; (c) Transmission spectra for the TM mode; (d) Perspective view of the isolator device; (e) Microscope image of the on-chip isolator device; (f) Transmission spectra for the TM mode
Fig. 8. MO-MR isolator[34,40]. (a) Schematic diagram of a non-reciprocal optical resonator; (b) Top-view optical micrograph of an MO-MR isolator; (c) Transmission spectrum of the isolator; (d) Optical microscope image of a TM-mode optical isolator based on Si3N4 waveguide resonators; (e) Transmission spectrum of the isolator
Fig. 10. Acousto-optic isolator[59]. (a) Representation of phase matching conditions in frequency-momentum space; (b) Schematic diagram of the phonon-photon interaction region; (c) Forward and backward transmission spectra under perfect phase matching conditions
Fig. 11. Acousto-optic isolator[10-12,61]. (a) Schematic diagram of the CFIDT; (b) Cross-section view of the acousto-optic interaction region;(c) Variation graph of isolation and insertion loss with frequency detuning; (d) Schematic diagram of the isolator device; (e) Cross-sectional view of the isolator device; (f) Transmission spectra of the isolator
Fig. 12. Electro-optic isolator[13]. (a) Working principle diagram of the MZM-based isolator; (b) Square-wave voltage signal; (c) Forward and backward transmission when modulating the MZM with the voltage shown in Fig. (b); (d) Forward and backward transmission under the driving frequency of 2.75 GHz
Fig. 13. Electro-optic isolator[14]. (a) Schematic of the isolator; (b) The illustration of the isolator in frequency domain; (c) Transmission spectra of the isolator
Fig. 14. Electro-optic isolator[15]. (a) Schematic of the electro-optic isolator; (b) Transmission spectra of the isolator in forward and backward directions; (c) Calculated isolation ratio for specified parameters at different wavelengths
Fig. 15. Nonlinear optical isolator [16,20]. (a) Schematic diagram of light isolation through Bragg scattering for forward-propagating light; (b) Case of backward propagation light; (c) Schematic diagram of the optical isolator. SPF: short-pass filter, LPF: long-pass filter; (d) Transmission spectra of the isolator, with the upper plot for forward-propagating light and the lower plot for backward-propagating light
Fig. 16. Nonlinear optical isolator [17-18,65]. (a) Schematic of spontaneous symmetry breaking in a microcavity; (b) Device diagram of a nonreciprocal isolator based on Kerr effect-induced fused silica microring; (c) Graph of the isolator's characteristics as a function of input power; (d) Microscope image of a Si3N4 isolator, scale bar: 100 μm; (e) Measured insertion loss and isolation peak under different coupling rates κ1 and κ2
Table 1. Performance comparison of on-chip integrated optical isolators based on magneto-optic effects
View tableView in ArticleTable 1. Performance comparison of on-chip integrated optical isolators based on magneto-optic effects
Device type Year Isolation ratio/dB Insertion loss/dB Isolation bandwidth/nm Polarization Platform Structure Ref MO-MZI 2000 4.90@1550 nm — — TM GaInAsP Waveguide [ 46 ]2004 9.90@1550 nm 25.0 — TM HfO2 Waveguide [ 47 ]2008 21.0@1559 nm 8.00 10@10 dB TM Si Waveguide [ 48 ]2012 25.0@1495 nm 9.70 0.40@20 dB TM Si Waveguide [ 38 ]2013 32.0@1540 nm 22.0 0.50@21 dB TE Si Waveguide [ 39 ]2014 30.0@1548 nm 13.0 1.0@20 dB TM Si Waveguide [ 7 ]2016 26.7@1553 nm 33.4 — TE Si Waveguide [ 31 ]2017 17.9@1562 nm 10.0 2.0@10 dB TE a-Si:H Waveguide [ 49 ]2017 29.0@1523 nm 9.00 18@20 dB TM Si Waveguide [ 50 ]2019 30.0@1574 nm 5.00 9.0@10 dB TM Si Waveguide [ 32 ]30.0@1588 nm 9.00 2.0@10 dB TE Si Waveguide 2020 32.0@1555 nm 2.30 4.0@20 dB TM Si3N4 Waveguide [ 40 ]30.0@1558 nm 3.00 5.0@20 dB TE Si3N4 Waveguide 2024 50.0@1550 nm 0.687 72@30 dB TM InP Waveguide [ 21 ]MO-MR 2011 19.5@1541.6 nm 18.8 0.040@10 dB TM Si Ring [ 8 ]2011 9.00@1550 nm — 0.040@5 dB TM Si Ring [ 41 ]2016 32.0@1555 nm 2.30 0.60@20 dB TM Si Ring [ 33 ]2017 11.0@1558 nm 9.70 0.16@5 dB TM Si Ring [ 51 ]2017 32.0@1555 nm — 3.0@20 dB TM Si Ring [ 43 ]2018 25.0@1550 nm 6.50 40@20 dB TE Si Ring [ 42 ]2018 40.0@1560.1 nm 3.00 — TM GeSbSe Ring [ 34 ]2019 20.0@1584.8 nm 11.5 — TE Si3N4 Ring [ 32 ]2020 28.0@1570.3 nm 1.00 — TM Si3N4 Ring [ 40 ]MO-MMI 2005 2.9@1550 nm — — TM InGaAsP Waveguide [ 9 ]2016 45@1550 nm 0.800 1.60@20 dB TM Si Waveguide [ 35 ]2018 16@1561 nm 3.40 — TE Si Waveguide [ 36 ]2021 15@1537.3 nm 5.00 2.00@10 dB TE Si Waveguide [ 52 ]2024 45@1550 nm 2.59 53.5@35 dB TM GaAs Waveguide [ 53 ]45@1550 nm 2.25 70.0@35 dB TM GaAs Waveguide
Table 2. Performance comparison of on-chip integrated optical isolators based on acousto-optic effects
View tableView in ArticleTable 2. Performance comparison of on-chip integrated optical isolators based on acousto-optic effects
Device type Year Isolation ratio/dB Insertion loss/dB Isolation bandwidth/nm Polarization Platform Structure Ref AO 2018 15.0@1550 nm — 0.0088@3 dB TE AlN Ring [ 59 ]2019 8.00@1540 nm — 0.0080@3 dB TE AlN Ring [ 61 ]2021 12.0@1523.7 nm 0.6 0.80@16 dB TE Si Waveguide [ 11 ]2021 39.3@1538 nm 1 0.0016@10 dB TE LiNbO3 Ring [ 10 ]2021 10.0@1545.55 nm 0.1 0.0056@8 dB TE Si3N4 Ring [ 12 ]
Table 3. Performance comparison of on-chip integrated optical isolators based on electro-optic effects
View tableView in ArticleTable 3. Performance comparison of on-chip integrated optical isolators based on electro-optic effects
Device type Year Isolation ratio/dB Insertion loss/dB Isolation bandwidth/nm Polarization Platform Structure Ref EO 2005 30.0@1550 nm 8.0 — — GaAs/ AlGaAs Waveguide [ 64 ]2015 12.5@1500 nm 5.5 90.0@12.5 dB — LiNbO3 Waveguide [ 13 ]2016 — 5.3 90.0@7 dB — LiNbO3 Waveguide [ 65 ]2021 13@1556 nm 18 0.0160@3 dB — Si Ring [ 66 ]2023 48.0@1553.2 nm 0.50 120@37 dB TE LiNbO3 Waveguide [ 14 ]2023 15.0@1550 nm 0.50 100@10 dB TE LiNbO3 Waveguide [ 15 ]
Table 4. Performance comparison of on-chip integrated optical isolators based on nonlinear optical effects
View tableView in ArticleTable 4. Performance comparison of on-chip integrated optical isolators based on nonlinear optical effects
Device type Year Isolation ratio/dB Insertion loss/dB Isolation bandwidth/nm Polarization Platform Structure Ref Kerr 2013 4.0@1582.3 nm — 8.00@4 dB — Si Waveguide [ 16 ]2017 30@1550 nm 7.0 — — Fused silica Ring [ 17 ]2022 23@1550 nm 4.6 — — Si3N4 Ring [ 18 ]17@1550 nm 1.3 — — Si3N4 Ring 2020 40@1570 nm 6.6 150@18 dB — LiNbO3 Waveguide [ 20 ]
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Zongqi Yang, Wenxiu Li, Xin Sun, Xinyao Huang, He Yang, Hao Zhang, Anping Huang, Zhisong Xiao. Research progress on on-chip integrated optical isolators[J]. Opto-Electronic Engineering, 2025, 52(2): 240285-1
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Received: Dec. 5, 2024
Accepted: Feb. 13, 2025
Published Online: Apr. 27, 2025
The Author Email: He Yang (张浩), Hao Zhang (杨合)
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