Paper Abstract and Keywords |
Presentation |
2010-05-21 15:00
Log-likelihood coherent optical receiver
-- High-speed ADCless Architecture -- Morio Toyoshima, Yozo Shoji, Yoshihisa Takayama (NICT), Takashi Maehata (SEI) SANE2010-13 |
Abstract |
(in Japanese) |
(See Japanese page) |
(in English) |
Coherent optical technologies have recently been receiving renewed interest in high bit rate communications. Such receivers have shot-noise-limited receiver sensitivity with sufficient local oscillator (LO) power; high frequency resolution at the intermediate frequency or baseband stage in highly dense frequency division multiplexed channels; improved receiver sensitivity compared with that of intensity modulation/direct detection (IMDD) systems; and active realization of multilevel signal transmission using not only intensity but also phase, frequency, and polarization states. While an optical phase-locked loop (PLL) that locks the LO phase to the signal phase is still difficult to achieve, digital signal processing (DSP) circuits are becoming increasingly faster, providing a simple and efficient means of estimating the carrier phase as well as the possibility of more powerful compensation for impairments in the electrical domain. The high-speed coherent receiver employs the so-called intradyne technique. This kind of receiver is based on a free-running LO laser and DSP. While this concept was proposed in 1991, the first implementation has been reported only recently. However, it requires high-speed analog-to-digital converters (ADCs) and the data rate cannot be enhanced without the development of the high-speed ADCs. In this paper, a log-likelihood coherent optical receiver is proposed, which consists of an optical part and an electrical part that includes comparators and digital circuits without ADCs. It is expected that the optical communications systems can be faster than that of current ones in the future. |
Keyword |
(in Japanese) |
(See Japanese page) |
(in English) |
Coherent optical communications / analog-to-digital converter / log-likelihood / digital signal processing / / / / |
Reference Info. |
IEICE Tech. Rep., vol. 110, no. 46, SANE2010-13, pp. 19-23, May 2010. |
Paper # |
SANE2010-13 |
Date of Issue |
2010-05-14 (SANE) |
ISSN |
Print edition: ISSN 0913-5685 Online edition: ISSN 2432-6380 |
Copyright and reproduction |
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