Simple approach for bidirectional performance enhancement on WDM-PONs with directmodulation lasers and RSOAs

Abstract

The extinction ratio (ER) for the downstream and upstream transmission signals needs to be compromised for the WDM-PON systems with directly modulated lasers at the center office and reflective semiconductor optical amplifiers at the user ends. We propose to enhance the performance by adding a FP etalon before the receiver of each optical network unit (ONU). The etalon performs spectral reshaping and then waveform reshaping to the downstream signals. This allows the use of low- ER downstream signals that reduce the intensity fluctuation of RSOA-remodulated upstream signals. This approach can also extend the transmission distance by reducing the transient chirp. Colorless operation can still be obtained since the same etalon can be used to enhance multiple wavelength channels. Experimental results verify considerable performance improvement on WDM-PONs with 10-Gbps and 1.25-Gbps data rates for the downstream and upstream transmission, respectively.

Simultaneous ER enhancement and light reuse scheme for RSOA-based wdm-PONs

“…The eye pattern is still wide open after 25-km transmission. The transient chirp of the DML signal can also be filtered out by the FP etalon [3,5]. Here we achieve simultaneous ER enhancement and data erasion by using a single FP etalon.…”

“…At the optical line terminal (OLT), directly modulated DFB lasers (DMLs) are frequently used to transmit downstream signals at high data rates. However, the transmission distance is limited by the chirp effects if the DMLs are modulated with high extinction ratio (ER) [4,5]. For example, to obtain good transmission performance by using DMLs at 10 Gbps over distances of tens of kilometers, the ER is usually 3 dB or lower.…”

“…For example, to obtain good transmission performance by using DMLs at 10 Gbps over distances of tens of kilometers, the ER is usually 3 dB or lower. To avoid power penalty from such a low ER, a Fabry-Perot etalon (FP etalon) or a filter is usually added before the receiver at the ONU to reshape the signals [3,5].…”

Injection locked Fabry–Perot laser diodes for WDM passive optical network spare function

“…In general, since the video signals demands a dedicated wavelength, the ONUs should be able to adapt tree different wavelength, which means the increasing cost and the system complexity. Accordingly, the bidirectional transmission over a single wavelength in WDM-PON has been proposed to overcome such problems [8,9], by which the bandwidth can be utilized efficiently and cost-effectively.…”

“…The characteristics of WDM-PON employing the FP-LD have been studied experimentally [3][4][5][6][7][8][9].The FP-LD with broad gain spectrum and multi-longitudinal modes can provide a wider operation wavelength range under injection locking, which could be an alternative method for WDM-PON spare function. In this paper, we propose a new 1:N protection scheme for the transmitters in WDM-PON utilizing an upstream injection locked FP-LD, and demonstrate that 36 channels with 100 GHz spacing can be protected against the problem downstream transmitters in the range from 1537.4 to 1565.4 nm.…”