Optical transmission performance for DML considering laser chirp and fiber dispersion using AMOOFDM

Abstract

International audienceFiber dispersion coupled with chirp parameter of the emitting laser impacts the optical transmission system performance. Fiber dispersion causes the propagating pulses to spread and overlap, and the chirp parameter produces a wavelength shift arising from the intensity variation of the directly modulated laser (DML). For optical transmission systems, orthogonal frequency division multiplexing (OFDM) modulation technique has proved to be an attractive approach to overcome optical fiber impairments in optical access networks as well as in long haul optical networks. Coupled with the Levin Campello bit-loading algorithm, adaptively modulated optical orthogonal frequency division multiplexing (AMOOFDM) optimizes the data rate by taking into consideration the channel quality of each subcarrier. This paper shows system performance for optical links starting with an optical back-to-back (BtB) connection and ending with 125 km of single mode fiber (SMF) with a fixed optical budget of 30 dB for all distances

SSII cancellation in an EAM-based OFDM-IMDD transmission system employing a novel dynamic chirp model

“…However, optical OFDM signals employing DMLs or EMLs will be optical double-side band (DSB) and frequency-chirped, resulting in detrimental dispersion-and chirp-related power fading. Since the power fading is periodic, a dynamic multi-band optical OFDM scheme [7][8][9] is proposed to solve the problem. In this scheme, the OFDM subcarriers can be dynamically allocated with adaptive modulation formats to the secondary passbands to make the best of bandwidth utilization.…”

Cost-effective 33-Gbps intensity modulation direct detection multi-band OFDM LR-PON system employing a 10-GHz-based transceiver

“…Nonetheless, one critical drawback of DMLs or EMLs is the generated optical signal will be double-side band (DSB) and frequency-chirped, which will result in detrimental dispersion-and chirp-related power fading. As a result, after 100-km transmission over single-mode fiber (SMF), the bandwidth of the transmission system is limited to a few GHz [11,12]. Thanks to the advance in digital-signal-processing (DSP) technology, both power levels and modulation levels of OFDM subcarriers can be adaptively allocated to efficiently utilize very limited transmission bandwidth at baseband.…”

“…Nonetheless, unlike wireless system, the fiber channel response is relatively stable, and power fading is periodic and predictable. Consequently, secondary lowfading bands have been proposed to carry supplementary OFDM subcarriers to achieve full utilization of transceiver bandwidth [12]. Nevertheless, within the range of 0-100 km, the lowest supporting data rate of 7 Gbps in [12] implies that the number of 1-Gbps ONU is restricted to only 7.…”

“…Consequently, secondary lowfading bands have been proposed to carry supplementary OFDM subcarriers to achieve full utilization of transceiver bandwidth [12]. Nevertheless, within the range of 0-100 km, the lowest supporting data rate of 7 Gbps in [12] implies that the number of 1-Gbps ONU is restricted to only 7. Hence, to support 128 ONUs, 19 wavelength channels are required and this will reduce the channel spacing and increase difficulties in wavelength management.…”

“…Moreover, the system could simply be upgraded to support 128 ONUs by using only four wavelengths for each direction (downstream and upstream). Thus, compared with the previous proposals of LR-PONs, our proposed 33-Gbps hybrid WDM/OFDM LR-PON optimizes the trade-off between the number of wavelength channels [2][3][4][5][6]8,9,12] and the cost of transceivers [7], based on cost-effective 10-GHz EML and PIN based IMDD scheme. 128 N W × = ) ONUs can be achieved by four wavelengths for each direction, and (e) Cost effective transceiver design is achieved by a 10-GHz IMDD scheme.…”