A Survey of Optical Carrier Generation Techniques for Terabit Capacity Elastic Optical Networks

Abstract

Abstract-Elastic optical networks (EON) have been proposed to meet the network capacity and dynamicity challenges. Hardware and software resource optimization and re-configurability are key enablers for EONs. Recently, innovative multi-carrier transmission techniques have been extensively investigated to realize high capacity (Tb/s) flexible transceivers. In addition to standard telecommunication lasers, optical carrier generators based on optical frequency combs (OFC) have also been considered with expectations of reduced cost and inventory, improved spectral efficiency and flexibility. A wide range of OFC generation techniques have been proposed in the literature over the past few years. It is imperative to summarize the state of the art, compare and assess these diverse techniques from a practical perspective. In this survey, we identify salient features of optical multicarrier generators, review and compare these techniques both from a physical and network layer perspective. OFC demultiplexing/filtering techniques have also been reviewed. In addition to transmission performance, the impact of such sources on the network performance and real-world deployment strategies with reference to cost, power consumption, and level of flexibility have also been discussed. Field trials, integrated solutions, flexibility demonstrations are also reported. Finally, open issues and possible future directions that can lead to real network deployment are highlighted.

Resonant electro-optic frequency comb

“…The resonant en- * harald.schwefel@otago.ac.nz hancement enables us to operate with microwave powers three orders of magnitude smaller than in commercially available devices. Such an implementation will be advantageous for next generation long distance telecommunication which relies on coherent emission and detection schemes to allow for operation with higher optical powers and at reduced cost [5].The data capacity of the internet is expected to grow by a factor of two every year [6], but current optical techniques are not able to meet the rising demand on the bandwidth of the undersea fibre network [7]. Techniques such as space division multiplexing [8], modedivision multiplexing [9] and wavelength division multiplexing (WDM) [5] in combination with time domain multiplexing (TDM) are being investigated to exploit the existing network to its full capacity.…”

Enhanced optical frequency comb generation by pulsed gain-switching of optically injected semiconductor lasers

“…In the same way as for other photonic technologies, the use of semiconductor sources for the generation of optical frequency combs (OFCs) is gaining increasing relevance due to the inherent advantages of the laser diodes in terms of high efficiency, low cost and small footprint, thus allowing to envisage prospects for the deployment of the technology outside the laboratory at a cost-effective price [1][2][3].…”

“…Gain-switching (GS) has proven its convenience as a method for generating OFCs due to its easy implementation, robustness and stability, controllable repetition rate, and adaptability for integration using generic platforms [4][5][6]. OFCs generated by GS have found applications mainly in optical communications [1,7] but also in sub-terahertz generation [8] and more recently in absorption spectroscopy [9,10]. The usual implementation of the GS technique for the generation of OFCs consists in driving the laser with the superposition of a direct bias current and a radio-frequency (RF) sinusoidal current.…”

Programmable SDN-Enabled S-BVT Based on Hybrid Electro-Optical MCM

“…The front-end modules can include multiple tunable lasers, to generate a set of orthogonal optical carriers, and external optical modulators such as Mach-Zehnder modulators (MZMs). Alternatively, cost/power efficient schemes, such as multi-wavelength locked lasers and PICs, can be adopted for generating the optical subcarriers [18], [21]. Then, the optical signal/slices can be multiplexed into a single flow with an optical orthogonal transform processor based on either the IFFT or the inverse DWPT (IDWPT) in order to create a spectrally efficient superchannel [14].…”