Applied Physics Seminar

Abstract: Photonic devices on silicon substrate are expected to fabricate large-scale PICs with low cost because they can be heterogeneously integrated with low-cost Si photonics devices. For this purpose, we have developed membrane photonic devices with lateral p-i-n structure on SiO2/Si substrate [1]. We employ epitaxial regrowth to fabricate buried heterostructure on directly-bonded thin III-V layer on SiO2/Si substrate, which allows us to employ large-scale Si substrate for fabricating lasers [2].
In addition to the cost issue, reducing the power consumption is quite important because it limits the integration density of PIC. In membrane structure, optical confinement factor in active region is increased compared with conventional device structure, which allows us to obtain high modulation efficiency. Therefore, by employing photonic crystal wavelength-scale cavity, we have demonstrated 10-Gbit/s NRZ signal modulation with 25 A bias current, resulting in ~4-fJ/bit operating energy [3,4]. We also demonstrated high efficiency modulator, in which InGaAsP/Si MOS capacitor was used for phase shifter [5].

References
[1] S. Matsuo et al, "Low-operating-energy directly modulated lasers for short-distance optical interconnects," Advances in Optics and Photonics, vol. 10 no. 3 pp. 567-643, 2018.
[2] S. Matsuo et al, "Directly modulated buried heterostructure DFB laser on SiO2/Si substrate fabricated by regrowth of InP using bonded active layer," Optics Express, vol. 22, no. 10, pp. 12139-12147 , 2014.
[3] S. Matsuo et al, "High-speed ultracompact buried heterostructure photonic-crystal laser with 13 fJ of energy consumed per bit transmitted," Nature Photonics, vol. 4, pp. 648-654, 2010.
[4] K. Takeda et al, "A few-fJ/bit data transmissions using directly modulated lambda-scale embedded active region photonic-crystal lasers," Nature Photonics, vol. 7, no. 7, pp. 569 – 575, 2013.
[5] T. Hiraki et al, "Heterogeneously integrated III–V/Si MOS capacitor Mach–Zehnder modulator,"
Nature Photonics, vol. 11, pp. 482-485, (2017).

More about the Speaker: Shinji Matsuo is a Senior Distinguished Researcher in NTT Device Technology Laboratories. He received a B.E. and M.E. in electrical engineering from Hiroshima University in 1986 and 1988 and a Ph.D. in electronics and applied physics from Tokyo Institute of Technology in 2008. In 1988, he joined NTT, where he researched photonic functional devices using VCSELs. Since 2000, he has been researching tunable lasers and low-operating energy directly modulated lasers. Recent his interest is heterogeneous integration of III-V compound semiconductors and Si photonics devices. He received the Izuo Hayashi Award from the Japan Society of Applied Physics (JSAP) in 2013. He is a member of the JSAP, IEICE, and a Fellow of IEEE.