Lab. members

Research activity

Magneto-Optical Devices and Application to All Optical signal Processing and Optical Sensors


@Optical communication has been applied to variety of modern life from long distance telecommunication to optical interconnection inside the electrical equipments. Unidirectional light propagation enables the robust operation of semiconductor optoelectronic devices and photonic integrated circuits (PICs) in which the input and output optical signals must be clearly separated. Optical isolators are one of the most important devices and are in great demand in semiconductor optoelectronics applications. The most important function of optical isolators is to protect semiconductor laser diodes (LDs) from unwanted reflected light. Conventional commercially available optical isolators are typically composed of Faraday rotators and two polarizers. Ferrimagnetic garnets, such as rare-earth iron garnets, are widely used as transparent, passive magneto-optic materials exhibiting Faraday rotation at telecommunication wavelengths. However, Faraday rotators and polarizers are free-space optical devices that cannot be integrated with III-V/Si - based optoelectronic devices and PICs. There is a strong demand for semiconductor waveguide optical isolators that can be monolithically integrated with LDs and III-V/Si - semiconductor waveguides for ultracompact PICs based on III-V semiconductors 1, 2). Integrated semiconductor optical isolators are expected to lead to the development of practical photonic ICs. First target of our research is to develop semiconductor optical isolators 3), 4) for photonic integrated circuits and thir application to all optical signal processing (optical flip-flop memories). Second target is to develop optical sensors based on ferromagnetic material on Si/SiO2 based optical waveguide devices for bioengineering applications. Si and SiO2 are chemically stable and there are matured nanofabrication technology, which is suitable for on-chip bio-sensing integrated with semiconductor lasers. 1) T. L. Koch and U. Koren, gSemiconductor photonic integrated circuitsh, IEEE J. Quantum Electron. 27, 641 (1991). 2) R. Nagarajan et al., gLarge-scale photonic integrated circuitsh, IEEE. J. Sel. Top. Quantum Electron. 11, 50 (2005). 3) H. Shimizu and Y. Nakano, gFabrication and Characterization of InGaAsP/InP Active Waveguide Optical Isolator With 14.7dB/mm TE Mode Nonreciprocal Attenuationh, IEEE Journal of Lightwave Technology 24, 38, (2006). 4) gMonolithic Integration of a Waveguide Optical Isolator With a Distributed Feedback Laser Diode in the 1.5-um Wavelength Rangeh, H. Shimizu and Y. Nakano, IEEE Photonics Technology Letters, 19, 1973-1975, (2007). (cover page)

@Main subjects

œSemiconductor optical isolators

@We have developed semiconductor optical isolators integrated with Ferromagnetic metal based on nonreciprocal loss. The amplifying semiconductor optical isolator can provide modified photon density redistribution, which can be applied to magnetically controllable semiconductor bistable lasers 4) and unidirectional semiconductor ring lasers. These devices enable optical flip-flop memories with series integration, and large scale photonic integrated circuits,all optical signal processing and optical sensing. 5) W. Zaets and K. Ando, IEEE Photonics Technol. Lett. 13, 185 (2001).

œControll of magnetic anistropy of magnetic garnets

@So far, external magnetic field has been necessary to reverse the magnetization of the magnetic materials, which required coil current. Magnetization reversals without coil current have been reported on ferromagnetic metal (Spin transfer torque / Voltage induced magnetization reversal). We are focusing on ferrimagnetic garnet and have investigated the magnetic anisotropy by introducing carrier and defects 6). The target of the research is to control the magnetic anisotropy for magnetization reversal without coil current. 6) D. A. Wahid, T. Hattori, J. Sato, and H. Shimizu, gPreparation and Characterization of Bi substituted gadolinium iron garnet Films by Metal Organic Decomposition and their Dependence on Annealing Gasesh, Journal of the Magnetics Society of Japan, 39 (3): 100-106 (2015).

œOptical isolators and sensors based on magneto-plasmon and on-chip integration

@Surface plasmon polaritons (SPPs) are quasi-particles generated from the coupling between an electromagnetic wave and the collective oscillations of a free electron gas at the interface of two media with permittivities of opposite signs (metal and dielectric). It has been shown that SPPs play an important role in systems presenting magneto-optical (MO) activity and plasmon resonances 7). @We have developed magnetic modulation and wavelength tunability of SPP excitations using Double-layer Dielectrics and Ferromagnetic Metal (DDFM) for integrated optical isolators and optical sensing. 7) G. Armelles, A. Cebollada, A. Garcia-Martin, and M. U. Gonzalez, Adv. Opt. Mater. 1, 10 (2013). 8) T. Kaihara, T. Ando, H. Shimizu, V. Zayets, H. Saito, K. Ando, and S. Yuasa, gEnhancement of magneto-optical Kerr effect by surface plasmons in trilayer structure consisting of double-layer dielectrics and ferromagnetic metalh, Optics Express, 23(9): 11537-11555 (2015). 9) T. Kaihara, H. Shimizu, A. Cebollada, and G. Armelles, gMagnetic field control and wavelength tunability of SPP excitations using Al2O3 / SiO2 / Fe structuresh Applied Physics Letters 109 (11):111102 (2016). (Editorfs pick, AppliedPhysicsLetters/)

œRemote sensing of the concentration of the global warming gases by fiber loop ring down methods

We have set up remote sensing of carbon dioxide, methane, by combining the technique of the optical fiber telecommunication. We measured carbon dioxide concentration of 0.05% by fiber loop ring down methods 10). 10) H. Shimizu and H. Noriyasu, gMeasurement of carbon dioxide concentration by fiber-loop ring-down spectroscopy for continuous remote measurementh Japanese Journal of Applied Physics 53(11):116601 (2014).

Publication list

Publication list

Presentations / Invited talks

Doctoral dissertation

Dr. Terunori KAIHARA "Study of performance improvement of magneto-optical surface plasmon polaritons with Fe", Mar. 2017, Doctor (Engineering)

Please contact to h-shmz atmark about the papers and questions about our research.


Seminar with collaborators

  • July 28, 2017
    Seminar among students of University of Hawai'i at Manoa, and Tokyo University of Agroculture and Technology(Program)
  • Nov. 13, 2015
    Symposium on magneto-plasmon(Program)