Data Rewriting After Carrier Erasing by Ultra-Long SOA

Abstract

Optical carrier erasing is demonstrated with evaluation of further remodulation up to 12.5Gbps. Small impairments achieved for all but the 7G-7G and 12.5G-12.5G cases, when spurious-pattern noise force higher penalties (respectively 2.3dB and 0.7dB).

Fiber link tests of wavelength reuse after amplitude erasure in semiconductor optical amplifier

“…The carrier reuse is implemented by passing the downstream signal through the data eraser and by another modulator driven by the upstream data, as used in Refs. and . The data eraser/rewriter consists of an optical isolator, a linear SOA acting as a preamplifier, an UL‐SOA, and a MZM.…”

“…Using an UL‐SOA (8‐mm long) as key device one takes advantage of the fast intraband effects, as the interband dynamics is completely saturated after the first quarter of the active optical guide. This erasing technique was demonstrated with good performance , and able to provide remodulated signal with high quality , although inherent self‐phase modulation (SPM) may limit overall performance (disabling the use in DWDM networks) . The working principle of the data eraser is shown in Figure .…”

“…Despite this drawback, good performance for the reused signal after erasure, up to 12.5 Gb/s, was presented in Ref. .…”

Semiconductor optical amplifier cavity length impact over data erasing/rewriting

“…The erased carriers optical spectra are also shown for both SOAs where the unwanted self‐phase modulation (SPM) can be noted, with more intense spectral broadening for the UL‐SOA, as expected. This is the main drawback of the proposed eraser [8, 9], noticeable if the dispersion effects in a further fiber link are significant.…”

“…Some proposed techniques to implement data erasing/rewriting have limited performance for amplitude modulated (AM) pseudo‐random bit sequence (PRBS) with input (downstream) modulation extinction ratio (ER) greater than 8 dB and/or for bit‐rates above 2.5 Gb/s [2–5]. Recently, these limits were overcome by using a deeply saturated ultra‐long (UL) SOA (8‐mm long active region, HHI ), with erasing demonstration for optical PRBS signals up to 12.5 Gb/s [6, 7], and wavelength reuse (carrier data rewriting) performance [8].…”