Lavery Domaniç, Behrens Carsten, Savory Seb J
Optical Networks Group, UCL Electronic & Electrical Engineering, Torrington Place, London, WC1E 7JE, United Kingdom.
Opt Express. 2011 Dec 12;19(26):B836-41. doi: 10.1364/OE.19.00B836.
The sensitivity of the four-dimensional modulation format, polarization-switched quadrature phase shift keying (PS-QPSK), is compared with polarization division multiplexed QPSK (PDM-QPSK), binary phase shift keying (PDM-BPSK) and 8-ary quadrature amplitude modulation (PDM-8QAM) at a constant bitrate (12.5 Gbit/s) using a preamplified signal to improve receiver sensitivity. The sensitivity without preamplification is also obtained. PS-QPSK is found to maintain a sensitivity advantage over the reference formats in line with theory with an absolute sensitivity of -52.7 dBm (4.2 photons/bit), assuming hard decision FEC.
在恒定比特率（12.5 Gbit/s）下，使用预放大信号来提高接收机灵敏度，将四维调制格式——极化切换正交相移键控（PS-QPSK）的灵敏度与极化分集复用正交相移键控（PDM-QPSK）、二进制相移键控（PDM-BPSK）和八进制正交幅度调制（PDM-8QAM）进行比较。还获得了无预放大时的灵敏度。结果发现，假设采用硬判决前向纠错（FEC），PS-QPSK在灵敏度方面相对于参考格式保持优势，绝对灵敏度为-52.7 dBm（4.2光子/比特），这与理论相符。
