Abstract:We fabricate a Mach-Zehnder interferometer-based optical isolator using a silicon-wire waveguide with magneto-optic garnet cladding using direct bonding techniques. Using Si-wire waveguides, the size of the device is greatly reduced from that of our previous device. We investigate surface-activated direct bonding with nitrogen plasma treatment, which shows better bonding results than oxygen plasma treatment. A large magneto-optic phase shift of 0.8π and an optical isolation of 18 dB are obtained at a wavelengt… Show more
“…6 was 8 μm (SOI core: 340 nm × 900 nm), which is still a resolution that is easily achieved with standard photolithography. Importantly, with a Stokes vector angle of 0.83π, we deduce a maximum isolation ratio of −11 dB, which is similar to ratios obtained with other first reports of new TM-mode isolator designs 1, 5, 6, 30 .Figure 6Performance of 340 nm SOI FR isolator with seedlayer-free Bi:TIG claddings. (top) The Stokes vector angle of opposite magnetic saturation, where a peak relative angle of 0.83π is observed.…”
The first experimental TE-mode silicon-on-insulator (SOI) isolators using Faraday Rotation are here realized to fill the ‘missing link’ in source-integrated near infrared photonic circuits. The isolators are simple 1D 2-element waveguides, where garnet claddings and longitudinal magnetic fields produce nonreciprocal mode conversion, the waveguide equivalent of Faraday Rotation (FR). Quasi-phase matched claddings are used to overcome the limitations of birefringence. Current experimental SOI isolators use nonreciprocal phase shift (NRPS) in interferometers or ring resonators, but to date NRPS requires TM-modes, so the TE-modes normally produced by integrated lasers cannot be isolated without many ancillary polarisation controls. The presented FR isolators are made via lithography and sputter deposition, which allows facile upscaling compared to the pulsed laser deposition or wafer bonding used in the fabrication of NRPS devices. Here, isolation ratios and losses of 11 dB and 4 dB were obtained, and future designs are identified capable of isolation ratios >30 dB with losses <6 dB.
“…6 was 8 μm (SOI core: 340 nm × 900 nm), which is still a resolution that is easily achieved with standard photolithography. Importantly, with a Stokes vector angle of 0.83π, we deduce a maximum isolation ratio of −11 dB, which is similar to ratios obtained with other first reports of new TM-mode isolator designs 1, 5, 6, 30 .Figure 6Performance of 340 nm SOI FR isolator with seedlayer-free Bi:TIG claddings. (top) The Stokes vector angle of opposite magnetic saturation, where a peak relative angle of 0.83π is observed.…”
The first experimental TE-mode silicon-on-insulator (SOI) isolators using Faraday Rotation are here realized to fill the ‘missing link’ in source-integrated near infrared photonic circuits. The isolators are simple 1D 2-element waveguides, where garnet claddings and longitudinal magnetic fields produce nonreciprocal mode conversion, the waveguide equivalent of Faraday Rotation (FR). Quasi-phase matched claddings are used to overcome the limitations of birefringence. Current experimental SOI isolators use nonreciprocal phase shift (NRPS) in interferometers or ring resonators, but to date NRPS requires TM-modes, so the TE-modes normally produced by integrated lasers cannot be isolated without many ancillary polarisation controls. The presented FR isolators are made via lithography and sputter deposition, which allows facile upscaling compared to the pulsed laser deposition or wafer bonding used in the fabrication of NRPS devices. Here, isolation ratios and losses of 11 dB and 4 dB were obtained, and future designs are identified capable of isolation ratios >30 dB with losses <6 dB.
“…A Ce:YIG layer was grown on an SGGG substrate through a sputter epitaxial growth technique. It should be noted that since the evanescent field penetrating the Ce:YIG layer is responsible for the magneto-optical phase shift, the thickness of intermediate layer between the silicon and garnet must be stringently controlled in order to obtain the desired magneto-optical phase shift [45]. …”
Silicon waveguide optical non-reciprocal devices based on the magneto-optical effect are reviewed. The non-reciprocal phase shift caused by the first-order magneto-optical effect is effective in realizing optical non-reciprocal devices in silicon waveguide platforms. In a silicon-on-insulator waveguide, the low refractive index of the buried oxide layer enhances the magneto-optical phase shift, which reduces the device footprints. A surface activated direct bonding technique was developed to integrate a magneto-optical garnet crystal on the silicon waveguides. A silicon waveguide optical isolator based on the magneto-optical phase shift was demonstrated with an optical isolation of 30 dB and insertion loss of 13 dB at a wavelength of 1548 nm. Furthermore, a four port optical circulator was demonstrated with maximum isolations of 15.3 and 9.3 dB in cross and bar ports, respectively, at a wavelength of 1531 nm.
“…Metal organic decomposition (MOD) method is a promising one to prepare magnetic garnet film, because it is a simple fabrication method which is composed of spin coating of the MOD solutions ( 12 thin films have been fabricated on (111) oriented gadolinium gallium garnet (GGG) single crystal substrates [9,10,11,12,13,14,15], and glass substrates [16]. In order to apply Bi:GdIG or Bi:YIG thin films in Si/SiO 2 based waveguide optical isolators [17,18,19] and MOSLMs [7], it is required that Bi:GdIG thin films are prepared on glass substrates or SiO 2 thin films. Since the MOD method enables it to prepare Bi:GdIG/Bi:YIG thin films by spin-coating and annealing process, it is possible to prepare these magnetic garnet thin films on the specific area in a substrate with different levels, such as optical waveguides.…”
Section: Introductionmentioning
confidence: 99%
“…This is a great advantage of the MOD method over conventional fabrication methods such as laser ablation and magnetron sputtering. However, it is not easy to fabricate Bi:GdIG thin films on glass substrates because of the differences in crystal structure and thermal expansion coefficient between Bi:GdIG/ Bi:YIG and glass substrate [17]. It is important to obtain magnetic garnet thin films having large FR and high magneto optical activity.…”
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