36 Gbit/s 16-QAM OFDM data transmission in DWDM-PON with a directly modulated and injection-locked WRC-FPLD
Date Issued
2014
Date
2014
Author(s)
Cheng, Min-Chi
Abstract
To build up a high-speed and low-cost optical access network, it is necessary to fuse a multiple carrier data format and a colorless transmitter based universal into the dense wavelength division multiplexing passive optical network (DWDM-PON) in the near future. The directly modulated transmission of optical 16 quadrature amplitude modulation (QAM) orthogonal frequency division multiplexing (OFDM) data-stream at its total bit rate up to 20 Gbit/s is demonstrated by up-shifting the relaxation oscillation peak and suppressing its relative intensity noise in a weak-resonant-cavity Fabry-Perot laser diode (WRC-FPLD) under injection-locking. With increasing the injection-locking power from -12 to -3 dBm, the effective reduction on threshold current of the WRC-FPLD significantly shifts its relaxation oscillation frequency from 5 to 7.5 GHz. This concurrently induces an up-shift of the peak relative intensity noise (RIN) of the WRC-FPLD, and effectively suppresses the background RIN level within the OFDM band between 3 and 6 GHz. The enhanced signal-to-noise ratio from 16 to 20 dB leads to a significant reduction of bit-error-rate (BER) of transmitted 16-QAM-OFDM data. After pre-leveling the peak amplitude of the OFDM subcarriers to compensate the throughput degradation of the directly modulated WRC-FPLD, the BER under 25-km SMF transmission can be further improved.
To further reduce the cost of the injection-locking master source, the partially coherent WRC-FPLD pair under master-to-slave injection-locking operation is demonstrated for optical 16-QAM OFDM transmission at 20 Gbit/s over 25-km SMF in DWDM-PON with 28 affordable channels achieving BER of below FEC-limit. After master-to-slave injection-locking, the BER of the 16-QAM OFDM data stream under back-to-back and 25-km transmissions can be improved from 3.3x10^-3 to 2.1x10^-5 and from 1.4x10^-1 to 1.2x10^-3, respectively. With OFDM subcarrier pre-leveling, the BER of 16-QAM OFDM data transmitted by the master-to-slave injection-locked WRC-FPLD over 25-km transmission is further improved from 1.2x10^-3 to 2.1x10^-4, concurrently enabling the 28 channel transmissions at 20 Gb/s with BER below FEC-limit of 3.8x10^-3.
Moreover, the overall frequency bandwidth of the TO-can packaged colorless WRC-FPLD can be extended from 5 to 9 GHz by replacing the package of the colorless WRC-FPLD from a typical 4-GHz TO-56-can to a 10-GHz TO-56-can. By injection-locking the WRC-FPLD based colorless transmitter packaged in a 10-GHz TO-56-can, the premier demonstration on directly modulated of 16 QAM OFDM transmission up to 36 Gbit/s per channel is demonstrated. The compromised optimization on enlarged modulation bandwidth and declined throughput power of the WRC-FPLD under strong injection-locking is considered, and the trade-off between the RIN suppression and the frequency response degradation with detuning the injection level is discussed. By pre-amplifying the directly modulated optical 16-QAM OFDM data stream covering a bandwidth up to 9 GHz with total raw bit rate of 36 Gbit/s, the receiving bit error rate (BER) under back-to-back transmission can be further reduced from 3.4x10^-3 to 2.1x10^-4. This enables the 36-Gbit/s 16-QAM OFDM transmission over 25-km SMF with its BER matching the FEC criterion at a receiving power of -3 dBm.
Subjects
弱腔雷射二極體
直接調變
注入鎖定
TO-can封裝
正交幅度調制正交分頻多工
Type
thesis
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