1991 Fiscal Year Final Research Report Summary
Complately velocity-matched traveling-wave type light modulator
| Project/Area Number |
58460140
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
電子機器工学
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| Research Institution | Kyoto University |
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Principal Investigator |
NAKAJIMA M. Kyoto Univ. Electronics, Assoc. Prof., 工学部, 助教授 (60025939)
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| Co-Investigator(Kenkyū-buntansha) |
湯川 敏信 京都大学, 工学部, 助手 (50109039)
AWAI I. Kyoto Univ. Electronics. Assistant, 工学部, 助手 (20026074)
YUKAWA T. Kyoto Univ. Electronics. Assistant
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| Project Period (FY) |
1983 – 1984
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| Keywords | Light modulation / Traveling wave / velocity matching / Light propagation / Optical integrated circuit / Optical communication |
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| Research Abstract |
The frequency of light wave is so high that it has a potentially ultrawideband information transmission capability. However, the present exploitation of the frequency bandwidth is within a few thousandths of that available in principle. This research is concerned with overcoming this situation.
The main causes of failure of utilizing the ultra-wide band of light wave reside in the modulation electronic circuits, the coupling of the circuits with the optical modulator and the mismatch between the velocity of light wave and that of the signal. Since 6th velocity of the signal wave is less than that of light wave in the optical modulator, a method were proposed to speed up the signal propagation. That is, the material with lower dielectric constant were inserted so that the modulation electrodes do not touch directly the dielectric material of the optical modulator, with care that the signal electric field to be applied to the modulator is not thereby reduced. We have also developed a numerical analysis method to combine the conformal mapping with the finite element method, enabling the computation of an open system of electrodes as encountered here. It was found that the frequency bandwidth is enlarged several times than that of the conventional traveling-wave modulator. Simultaneously we have endeavored to enhance the modulation efficiency by designing a 3 dimensional optical waveguide.
With this procedure the quality of the optical modulators were much improved, and after this research similar investigations have been carried out in various institutes. Still, this means that only a small fraction of ultrawide bandwidth of light wave has been exploited. Since there are other factors to limit the bandwidth as mentioned above, some ways to surpass these difficulties were also proposed. Yet, even if the ultra-high-speed modulation has been achieved, it has little meaning, unless ultra-high-speed demodulation is also possible. A solution of this problem has been suggested.
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Research Products
(17 results)
