All-optical NRZ-to-RZ reconversion from the red-chirped NRZ signal generated by the RZ-to-NRZ converter using an SOA-loop-mirror

Abstract

Abstract:This paper aims to demonstrate experimentally a new all-optical non-return-to-zero (NRZ) to return-to-zero (RZ) data format reconversion from the red-chirped NRZ signal, generated by the RZ-to-NRZ converter, using a semiconductor optical amplifier in a fiber loop mirror (so-called an SOA-loop-mirror). The primary merit of the proposed NRZ-to-RZ reconversion is that no additional optical clock is required in the process, unlike other conventional methods. While the optical power penalty for the RZ-to-NRZ conversion using an SOA-loop-mirror was 1.64 dB, the proposed NRZ-to-RZ reconversion penalty was 0.6 dB compared to that of the original input RZ signal.

All-Optical Bit-Rate Flexible NRZ-to-RZ Conversion Using an SOA-Loop Mirror and a CW Holding Beam

“…A pulse compressor [18] was used to reduce the pulse width of the converted RZ signal for a 40 Gb/s OTDM signal through a bit-interleaving technique. For NRZ-to-RZ conversion, the previously developed SOA-loop mirror [5,6,14,15] was used. It consisted of a TDC1, an OTDL, a PC4, and an SOA.…”

“…It is cascaded with an optical time-interleaved circuit to make a 40 Gb/s OTDM channel. Previously an NRZ-to-RZ converter [5,6,14,15] using an SOA in a fiber-loop mirror (i.e., an SOA-loop mirror) was reported, but the method proposed in this paper has a different operating principle compared to that previous NRZ-to-RZ converter. In this study, a continuous-wave (CW) holding beam is used to reduce the gain recovery time of the SOA [16,17] to help in obtaining symmetric RZ pulses converted at the rising and falling edges of an input NRZ signal.…”

“…For this NRZ-to-RZ conversion, the same structure as in the prior literature [5,6,14,15] is employed, but the principle is different. A CW holding beam is used to reduce the gain recovery time of the SOA, yielding symmetric RZ pulses with the same width and shape at the rising and falling edges of the input NRZ signal, at any bit rate.…”

“…An appreciable number of all-optical data-format conversions have been reported, including semiconductor optical amplifier (SOA) gain compression [1,2], a monolithically integrated Michelson interferometer (MI) employing SOAs [3], an SOA/fiber grating wavelength converter [4], a nonlinear optical loop mirror (NOLM) with SOA [5][6][7]15], cross-phase modulation (XPM) and/or four-wave-mixing (FWM) in a nonlinear photonic crystal fiber [8] or a Mach-Zehnder interferometer (MZI) employing SOAs [9], and a FabryPerot (FP) laser diode with dual-wavelength injection locking [10,17]. Currently, research has been extended to all-optical format conversions between on-off keying (OOK) and phase-shift keying (PSK) [11,12].…”