2005 Fiscal Year Final Research Report Summary
Study of ultrafast optical buffer memory using long wavelength VCSELs
| Project/Area Number |
16360025
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Applied optics/Quantum optical engineering
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| Research Institution | Yamagata University |
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Principal Investigator |
KAWAGUCHI Hitoshi Yamagata University, Faculty of Engineering, Professor, 工学部, 教授 (40211180)
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| Co-Investigator(Kenkyū-buntansha) |
TAKAHASHI Yutaka Yamagata University, Faculty of Engineering, Associate Professor, 工学部, 助教授 (00260456)
KATAYAMA Takeo Yamagata University, Faculty of Engineering, Research Assistant, 工学部, 助手 (80313360)
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| Project Period (FY) |
2004 – 2005
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| Keywords | vertical-cavity surface-emitting laser / optical bistability / polarization switching / all-optical buffer memory / shift register / optical packet switching / photonic network / lone-waveleneth VCSEL |
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| Research Abstract |
We investigated mainly the following four topics to create the all-optical buffer memory working in the long-wavelength region.
1. We have prepared VCSELs with a square mesa-structure. The polarization bistable switching was obtained by injection of optical pulses. We demonstrated the record low switching energy of 0.2 fJ and 0.3 fJ for the set and reset optical pulses and the record high switching frequency of 10 GHz in the flip-flop operation.
2. We proposed a novel 3R regenerator based on the polarization bistability in VCSELs. The VCSEL output signal through a polarizer becomes the regenerated signal which has the same bit pattern as the data signal. The rise and the fall timings of the VCSEL output are determined by the timings of the set pulse and the reset pulse. Thus, the timing jitter of the data signal is reduced. In our experiment, the peak-to-peak timing jitter of 2 ns was reduced to 0.7 ns.
3. We have proposed the optical buffer memory using a two-dimensional array of the polarization bistable VCSELs. First, the polarization of the VCSELs are reset by an optical reset pulse. Optical signals are converted to spatially parallel signals and injected into the VCSELs together with optical set pulses. Only when the optical signals and the optical set pulses are simultaneously injected into the VCSELs, the VCSELs change their polarization. Therefore, the VCSELs emit the outputs with the polarization which depend on '0' and '1' of the input signal. The output signal pulses are created from the CW 0° output of the VCSELs and are converted to an ultrafast optical signal. We have experimentally demonstrated 1-bit optical buffering.
4. We have made a 1.55 μm VCSEL structure have obtained laser oscillation by optical pumping. This result makes the optical buffer memory possible in the long wavelength region.
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