1998 Fiscal Year Final Research Report Summary
Study of ultrafast all-optical flip-flop operation with vertical-cavity surface-emitting lasers
| Project/Area Number |
08455029
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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)
MATSUSHITA Koichi Yamagata University, Faculty of Engineering, Associate Professor, 工学部, 助教授 (70124625)
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| Project Period (FY) |
1996 – 1998
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| Keywords | Semiconductor laser / Optical bistability / Pitchfork bifurcation bistability / Vertical-cavity surface-emitting laser / All optical flip-flop operation / Polarization switching / Demultiplexing / Gain saturation |
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| Research Abstract |
We have investigated mainly the following four topics to create new nonlinear optical functional devices based on the pitchfork bifurcation bistable operation of vertical-cavity surface-emitting lasers (VCSEL).
(1) We observed the pitchfork bifurcation polarization bistability and successfully demonstrated all-optical flip-flop operation in a VCSEL.Switching between the two polarization states was accomplished by injecting trigger optical input, We also achieved the ultrafast polarization bistable switching with a switching time of 7ps by using picosecond optical trigger pulses.
(2) We numerically analyzed an all-optical flip-flop operation using a polarization bistable VCSEL.We used rate equations taking into account gain saturation in the VCSEL and detuning of the incident optical beam frequency from the cavity resonant frequency of the VCSEL.We have clarified the most suitable operation conditions for the ultrafast flip-flop operation. The all-optical flip-flop can be obtained up to 3
… More
00 Gbit/s.
(3) The relative magnitude of self- and cross-saturation coefficients are crucial to determine the characteristics of polarization switching. In order to obtain the detailed properties of nonlinear gain, we studied numerically the nonlinear gain coefficient for the optical fields in parallel and orthogonal polarization. The numerical calculation confirmed that the relation between self-and cross-saturation coefficients satisfies the condition for polarization bistability.
(4) We newly proposed a demultiplexing (DEMUX) device. When the input signal and the gate pulse are injected simultaneously into the polarization bistable laser diode (BLD) with TE polarization, the polarization of the BLD is set to TE polarization using its AND gate function. Then, laser oscillation in TE polarization continues until the reset pulse with TM polarization is injected. Thus, the optical demultiplexing with a signal-bit width conversion function is achieved in the TE polarization output signal. Our results show that the ultrafast all-optical demultiplexing from a 50 Gbit/s signal to a 5 Gbit/s RZ signal can be obtained. Less
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