Time–Frequency Packing Applied to Cost-Effective IM/DD Transmission Based on Directly Modulated VCSEL

Abstract

Potential of directly modulated vertical cavity surface emitting lasers (VCSELs), widely employed for low-cost and energy-efficient intradata center transmissions, is here studied for transmissions up to access/metro scenarios. In particular, the manuscript refers to long-wavelength VCSELs for intensity modulation/direct detection (IM/DD) ON-OFF keying transmission over standard single-mode fiber (SSMF). The intent of this paper primarily consists of demonstrating information rate and fiber reach enhancement in potentially uncooled environments or with relaxed thermal management requirements through the use of timefrequency packing (TFP) technique in a VCSEL-based transmission. TFP has been applied here to IM/DD transmission for the first time, although not in a multiple channel system. The digital signal processing unit implementation is clearly simplified with respect to coherent systems (no frequency synchronization and no phase error recovery), where TFP was firstly introduced, as it only takes into account the photo-detected signal intensity, regardless of the phase information. On the other hand, the signal processing is here more complex than in a traditional IM/DD system. Through the use of a commercial C-band 4 G VCSEL, net information rate up to 12.5 and 11.2 Gb/s has been measured for 25 and 45 km of SSMF, respectively, in an unamplified optical link and with power budget equal to 19 and 16 dB, respectively. The transmission is intrinsically polarization independent and wavelength independent and tolerance to temperature increase up to 60°C has been analyzed together with energy consumption.

Low-Timing-Jitter and Low-Phase-Noise Microwave Signal Generation Using a VCSEL-Based Optoelectronic Oscillator

“…The vertical-cavity surface-emitting lasers are semiconductor lasers widely used in telecommunications at high transfer rates through different modulation formats, such as direct modulation (Malacarne et al, 2017), discrete multitone modulation (DMT) (Wagner et al, 2017) and four-level pulse amplitude modulation (PAM-4) (Lavernick et al, 2017). While multimode VCSELs at short-wavelengths (850 -1 050 nm) are employed in short-reach fiber links (Pavan, Lavrencik and Ralph, 2017) and visible light transmissions (Li-Fi) at 680 nm (Lu et al, 2017), long-wavelength VCSELs (LW-VCSEL) in the 1,2 -1,6 µm range, are used in long-haul communications (Bacou et al , 2010).…”

Análisis del Impacto de la Conversión Analógica a Digital en el Desempeño de Sistemas RoF Digitalizado

“…La potencia de salida óptica y el voltaje asociado deben ser medidos como función de la Corriente Directa (DC) de alimentación para el rango de temperatura sugerido por la hoja de especificaciones del fabricante. Debe identificarse el umbral de corriente que habilita la máxima potencia de salida que en las curvas usualmente decrece (roll-over) para valores entre 6 a 8 mA [14]. Por tanto, se alimentó el VCSEL con una corriente de 6.5 mA emitiendo a una potencia de -13 dBm a temperatura ambiente.…”