5. まとめ
半導体光増幅器内の周波数チャープを用いた光A/D変換技術を紹介した。半導体光増幅器で発生する周波数チャープは増幅された信号光に周波数変化を与え，伝送特性に影響を与えるというデメリットがあるが，提案手法ではこれを逆手に取って，光強度−周波数変換に応用した光A/D変換を提案し，サンプリング速度10 GSample/sでの実証実験に成功した。今後もさらなる高性能化を目指した研究開発を進めて行きたい。
参考文献
1）B. L. Shoop: “Photonic analog-to-digital conversion,”
2）G. C. Valley: “Photonic analog-to-digital converters,” Opt. Express, 15, 1955-1982 (2007).
3）A. Khilo et al.: “Photonic ADC: overcoming the bottleneck of electric jitter,” Opt. Express, 20, 4454-4469 (2012).
4）T. Konishi et al.: “All-optical analog-to-digital converter by use of self-frequency shifting in fiber and a pulse-sharping technique,” J. Opt. Soc. Am B, 19, 2817-2823 (2002).
5）S. Oda et al.: “A novel quantization scheme by slicing supercontinuum spectrum for all-optical analog-to-digital conversion,” IEEE Photon. Technol. Lett., 17, 465-467 (2005).
6）Y. Miyoshi et al.: “Multiperiod PM-NOLM with dynamic counter-propagating effects compensation for 5-bit all-optical analog-to-digital conversion and its performance evaluations,” J. Lightwave Technol., 28, 415-422 (2010).
7）M. Scaffardi et al.: “Analog-to-digital conversion based on modular blocks exploiting cross-gain modulation in semiconductor optical amplifiers,” IEEE Photon. Technol. Lett., 21, 540-542 (2009).
8）M. Matsuura et al.: “Time-resolved chirp properties of SOAs measured with an optical bandpass filter,” IEEE Photon. Technol. Lett., 20, 2001-2003 (2008).
9）M. Matsuura et al.: “Experimental investigation of chirp properties induced by signal amplification in quantum-dot semiconductor optical amplifiers,” Opt. Lett., 40. 914-917 (2015).
10）N. Ninomiya et al.: “Optical quantization based on intensity to frequency conversion using frequency chirp in a QD-SOA,” Proc. of OFC 2017, Th1F. 6, Los Angeles, USA (2017).
11）H. Hoshino et al.: “Photonic analog-to-digital conversion using red frequency chirp in a semiconductor optical amplifier,” Opt. Lett., 43, 2272-2275 (2018).
12）M. Matsuura et al.: “320-Gbit/s wavelength conversion using four-wave mixing in quantum-dot semiconductor optical amplifiers,” Opt. Lett., 36, 2910-2912 (2011).
13）M. Matsuura et al.: “Ultrahigh-speed and widely tunable wavelength conversion based on cross-gain modulation in a quantum-dot semiconductor optical amplifier,” Opt. Express, 19, B551-B559 (2011).
14）M. Matsuura et al.: “320-to-40-Gb/s optical demultiplexing using four-wave mixing in a quantum-dot SOA,” IEEE Photon. Technol. Lett., 24, 101-103 (2012).
15）M. Matsuura et al.: “Error-free 320-to-40-Gbit/s optical demultiplexing based on blue-shift filtering in a quantum-dot semiconductor optical amplifier,” Opt. Lett., 38, 238-240 (2013).
2）G. C. Valley: “Photonic analog-to-digital converters,” Opt. Express, 15, 1955-1982 (2007).
3）A. Khilo et al.: “Photonic ADC: overcoming the bottleneck of electric jitter,” Opt. Express, 20, 4454-4469 (2012).
4）T. Konishi et al.: “All-optical analog-to-digital converter by use of self-frequency shifting in fiber and a pulse-sharping technique,” J. Opt. Soc. Am B, 19, 2817-2823 (2002).
5）S. Oda et al.: “A novel quantization scheme by slicing supercontinuum spectrum for all-optical analog-to-digital conversion,” IEEE Photon. Technol. Lett., 17, 465-467 (2005).
6）Y. Miyoshi et al.: “Multiperiod PM-NOLM with dynamic counter-propagating effects compensation for 5-bit all-optical analog-to-digital conversion and its performance evaluations,” J. Lightwave Technol., 28, 415-422 (2010).
7）M. Scaffardi et al.: “Analog-to-digital conversion based on modular blocks exploiting cross-gain modulation in semiconductor optical amplifiers,” IEEE Photon. Technol. Lett., 21, 540-542 (2009).
8）M. Matsuura et al.: “Time-resolved chirp properties of SOAs measured with an optical bandpass filter,” IEEE Photon. Technol. Lett., 20, 2001-2003 (2008).
9）M. Matsuura et al.: “Experimental investigation of chirp properties induced by signal amplification in quantum-dot semiconductor optical amplifiers,” Opt. Lett., 40. 914-917 (2015).
10）N. Ninomiya et al.: “Optical quantization based on intensity to frequency conversion using frequency chirp in a QD-SOA,” Proc. of OFC 2017, Th1F. 6, Los Angeles, USA (2017).
11）H. Hoshino et al.: “Photonic analog-to-digital conversion using red frequency chirp in a semiconductor optical amplifier,” Opt. Lett., 43, 2272-2275 (2018).
12）M. Matsuura et al.: “320-Gbit/s wavelength conversion using four-wave mixing in quantum-dot semiconductor optical amplifiers,” Opt. Lett., 36, 2910-2912 (2011).
13）M. Matsuura et al.: “Ultrahigh-speed and widely tunable wavelength conversion based on cross-gain modulation in a quantum-dot semiconductor optical amplifier,” Opt. Express, 19, B551-B559 (2011).
14）M. Matsuura et al.: “320-to-40-Gb/s optical demultiplexing using four-wave mixing in a quantum-dot SOA,” IEEE Photon. Technol. Lett., 24, 101-103 (2012).
15）M. Matsuura et al.: “Error-free 320-to-40-Gbit/s optical demultiplexing based on blue-shift filtering in a quantum-dot semiconductor optical amplifier,” Opt. Lett., 38, 238-240 (2013).
16）T. Okada et al.: “10-GSample/s, 15-level optical quantization using frequency chirp in a quantum-dot SOA,” Proc of OECC 2018, 1-26, Jeju, Korea (2018).
■Photonic Analog-to-Digital Conversion Using a Semiconductor Optical Amplifier
■Motoharu Matsuura
■Graduate School of Informatics and Engineering, University of Electro-Communications, Associate Professor
マツウラ モトハル
所属：電気通信大学 情報理工学研究科 准教授
（月刊OPTRONICS 2018年9月号）
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