Fig. 6: Measurement of 16QAM, 32QAM, and 64QAM signals at a symbol rate of 320 GBd at various optical signal-to-noise ratio (OSNR) levels. | Light: Science & Applications

Fig. 6: Measurement of 16QAM, 32QAM, and 64QAM signals at a symbol rate of 320 GBd at various optical signal-to-noise ratio (OSNR) levels.

From: Optical arbitrary waveform generation (OAWG) using actively phase-stabilized spectral stitching

Fig. 6

The OSNR is measured in a single polarization with respect to the standard reference bandwidth of 12.5 GHz, thus only including ASE noise that is co-polarized with the signal under test. a Constellation signal-to-noise ratio (CSNR) as a function of the OSNR for various modulation formats. The inset shows an exemplary 64QAM constellation diagram. b Bit-error ratio (BER) before applying forward-error correction (FEC) vs. OSNR. c Achievable information rate (AIR) vs. OSNR. The AIR was calculated according to Eq. (7) based on the normalized generalized mutual information (NGMI), which was estimated form the constellation diagrams

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