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1 0 0 0 OA Dynamic response of modulators based on cascaded-ring-resonator

著者: Akiyama Suguru Nomura Shintaro
出版者: Optical Society of America
雑誌: Optics Express (ISSN:10944087)
巻号頁・発行日: vol.20, no.20, pp.21847-21859, 2012-09
被引用文献数: 4

We investigated the dynamic response of a cascaded-ring-resonator-loaded Mach–Zehnder modulator (CRR-MZM), in which a number of cascaded ring resonators (RRs) are loaded in the interferometer as phase modulators. The analytical form is derived for the small-signal response of CRR-MZM using temporal-coupled-mode (TCM) theory, and its validity is confirmed by numerical calculations. It is revealed that the bandwidth of the CRR-MZM is maximized by setting proper delays in driving signals between neighboring RRs; the optimized delay is twice the photon lifetime of each RR. The calculated performances of CRR-MZMs are compared with those of standard modulators based on a single-ring-resonator (SRR) without interferometer, in terms of the modulation depth and bandwidth. For a given degree of the refractive index change in a waveguide, CRR-MZM can provide a larger modulation depth than a SRR-type modulator in frequency ranges exceeding 25 GHz.

2012-11-09 08:37:02
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1 0 0 0 OA Cascaded-ring-resonator-loaded Mach–Zehnder modulator for enhanced modulation efficiency in wide optical bandwidth

著者: Akiyama Suguru Kurahashi Teruo Morito Ken Yamamoto Tsuyoshi Usuki Tatsuya Nomura Shintaro
出版者: Optical Society of America
雑誌: Optics Express (ISSN:10944087)
巻号頁・発行日: vol.20, no.15, pp.16321-16338, 2012-07
被引用文献数: 14 2

A cascaded-ring-resonator-loaded Mach–Zehnder modulator (CRR-MZM) is presented in which a number of cascaded ring resonators (RRs) are loaded in the interferometer as phase modulators. The ability of the design to provide enhanced modulation efficiency at a wide optical bandwidth is demonstrated in comparison with a conventional single-RR-type modulator without an interferometer. The optimization of RRs for the CRR-MZM is investigated experimentally by measuring the transmission spectra in both intensity and group delay of RRs having various structural parameters. Using the optimized parameters, we fabricated a CRR-MZM with 10 cascaded RRs loaded on each arm of the interferometer on a silicon-on-insulate substrate. The RRs had pin-diodes along the waveguides, which were operated with forward bias voltage. Its modulation efficiency was enhanced by a factor of 4.4 at the expense of additional loss of less than 3.5 dB compared with a standard non-resonant MZM. 10 Gb/s-operations of CRR-MZM were successfully demonstrated using pre-emphasized RF signals with amplitude of 1.5 Vpp in a wavelength range of 2 nm.

2012-11-09 08:36:56
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1 0 0 0 OA Inference on High-Dimensional Mean Vectors with Fewer Observations Than the Dimension

著者: Yata Kazuyoshi Aoshima Makoto
出版者: Springer US
雑誌: Methodology and computing in applied probability (ISSN:13875841)
巻号頁・発行日: vol.14, no.3, pp.459-476, 2012-09
被引用文献数: 3 5

We focus on inference about high-dimensional mean vectors when the sample size is much fewer than the dimension. Such data situation occurs in many areas of modern science such as genetic microarrays, medical imaging, text recognition, finance, chemometrics, and so on. First, we give a given-radius confidence region for mean vectors. This inference can be utilized as a variable selection of high-dimensional data. Next, we give a given-width confidence interval for squared norm of mean vectors. This inference can be utilized in a classification procedure of high-dimensional data. In order to assure a prespecified coverage probability, we propose a two-stage estimation methodology and determine the required sample size for each inference. Finally, we demonstrate how the new methodologies perform by using a microarray data set.

2012-11-09 08:36:51
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1 0 0 0 OA Authors’ Response

著者: Aoshima Makoto Yata Kazuyoshi
出版者: Taylor & Francis
雑誌: Sequential analysis (ISSN:07474946)
巻号頁・発行日: vol.30, no.4, pp.432-440, 2011-11
被引用文献数: 6

In this article, we respond to the comments made by the 10 discussants on “Two-Stage Procedures for High-Dimensional Data.” We also give some new results along with their brief explanations.