Beyond the 100 Gbaud directly modulated laser for short reach applications

Abstract

It is very attractive to apply a directly modulated laser (DML)-based intensity-modulation and direct-detection (IM/DD) system in future data centers and 5G fronthaul networks due to the advantages of low cost, low system complexity, and high energy efficiency, which perfectly match the application scenarios of the data centers and 5G fronthaul networks, in which a large number of high-speed optical interconnections are needed. However, as the data traffic in the data centers and 5G fronthaul networks continues to grow exponentially, the future requirements for data rates beyond 100 Gbaud are challenging the existing DML-based IM/DD system, and the main bottleneck is the modulation bandwidth of the DML. In this paper, the data rate demands and technical standards of the data centers and 5G fronthaul networks are reviewed in detail. With the modulation bandwidth requirements, the technical routes and achievements of recent DMLs are reviewed and discussed. In this way, the prospects, challenges, and future development of DMLs in the applications of future data centers and 5G fronthaul networks are comprehensively explored.

Optical transmitter module with hybrid integration of DFB laser diode and proton-exchanged LiNbO3 modulator chip

“…Lithium niobate (LiNbO 3 ) single crystals have been recognized as the most mature material for electro-optic modulators thanks to their Pockels effect [1] . Compared with modulators based on the carrier effect or microring structuressuch as direct modulation lasers [2,3] , InP modulators [4] , and silicon-based modulators [5] , broadband LiNbO 3 Mach-Zehnder (MZ) modulators with the advantages of broad bandwidth, high extinction ratio, very low chirp, and high stability [6] have been widely used in optical communication backbone transmission networks, high-performance broadband optical links, and radio-frequency (RF) photonics, and have attracted considerable attention in the last century. However, the incompatibility between the LiNbO 3 chip fabrication process and the complementary metal-oxide-semiconductor (CMOS) process has brought significant obstacles in hybrid integration research based on LiNbO 3 modulators.…”

Net 67 Gbps Transmission Over 2 km at Sub 1 Vpp Using Packaged Silicon Photonic MZM

“…Thus, PAM4 has been standardized for short reach interconnects up to 10 km because of its simplicity and lower power requirements compared to the other modulation formats [1]. PAM modulation can be achieved through using directly modulated lasers (DMLs) [2], externally modulated lasers (EMLs) [3], or external optical modulators [4][5][6][7][8][9]. The main material systems used in fabricating these modulators are lithium niobite (LiNbO3), indium phosphide (InP), gallium arsenide (GaAs), and silicon (Si), out of which silicon is the only material system that is fully compatible with the complementary metal oxide semiconductor (CMOS) processing.…”

Compact optical convolution processing unit based on multimode interference

“…However, in present schemes, mainly based upon the von Neumann computing paradigm, there is an inherent trade-off between the data exchange speed and the energy consumption; this is mainly because in these schemes, the memory and process unit are separated [8][9][10][11] .Optical neural networks (ONNs) are regarded as promising candidates for the next generation of neuromorphic hardware processors. Photonics devices have low interconnect loss and can overcome the bandwidth bottleneck of their electrical counterparts to achieve ultrahigh computing bandwidth up to 10 THz [12][13][14][15][16][17] . Additionally, the light transmission in the ONN simultaneously implements data processing, which effectively avoids data tidal transmission in the von Neumann computing paradigm.…”

“…Optical neural networks (ONNs) are regarded as promising candidates for the next generation of neuromorphic hardware processors. Photonics devices have low interconnect loss and can overcome the bandwidth bottleneck of their electrical counterparts to achieve ultrahigh computing bandwidth up to 10 THz [12][13][14][15][16][17] . Additionally, the light transmission in the ONN simultaneously implements data processing, which effectively avoids data tidal transmission in the von Neumann computing paradigm.…”