Integrated space-division multiplexed (SDM) erbium-doped fiber amplifiers (EDFAs) are not only inevitable for SDM systems, but can be an alternative solution to nowadays EDFA array for parallel amplification. SDM EDFAs are expected to provide substantial complexity and cost savings through spatial-integration compared to duplicating single-mode fiber amplifiers. High output power and low noise figure can be achieved by cladding-pumped SDM EDFAs. In this paper, different cladding pumping solutions, cladding-pumped single-mode and multimode multi-core EDFAs will be discussed.
Various space division multiplexing (SDM) schemes are currently investigated as a way to overcome the capacity limit
of data links. We here focus on mode division multiplexing (MDM) in a multi-mode fiber (MMF). Towards long-haul
data transmission, for which signal amplification is a key enabling component, we investigate a simple approach to
precisely control the mode-dependent gain (MDG) between the co-propagating LP<sub>01</sub> and LP<sub>11</sub> modes of an erbium-doped
few-mode fiber amplifier (MM-EDFA) by engineering a multi-ring doping profile. In practice, the mode dependent loss
of the few-mode transmission fiber must be taken into account in order to equalize the gain for all modal channels. In a
step towards practical implementation of MM-EDFA for long-haul SDM, we extend the single ring doping approach to
incorporate multi-ring and multi-level doping. Through numerical simulations we study the optimization of the width
and doping level of each ring so as to control the MDG. We further discuss the possibility of modal gain equalization
through zero-differential modal gain (ZDMG) points in a single stage MM-EDFA, or via tuning of pump powers in a
dual-stage MM-EDFA configuration.
The heavy metal oxide glasses containing bismuth such as bismuth sesquioxide show unique high refractive index. In
addition, the bismuth-oxide based glass does not include toxic elements such as Pb, As, Se, Te, and exhibits well
chemical, mechanical and thermal stability. Hence, it is used to fabricate high nonlinear fiber for nonlinear optical
application. Although the bismuth-oxide based high nonlinear fiber can be fusion-spliced to conventional silica fibers
and have above advantages, yet it suffers from large group velocity dispersion because of material chromatic dispersion
which restricts its utility.
In regard to this, the micro-structure was introduced to adjust the dispersion of bismuth-oxide high nonlinear fiber in
the 1550nm wave-band. In this paper, a hexagonal solid-core micro-structure is developed to balance its dispersion and
nonlinearity. Our simulation and calculation results show that the bismuth-oxide based photonic crystal fiber has near
zero dispersion around 1550nm where the optical parametric amplification suitable wavelength is. Its dispersion slop in
the communication wavelength range is also relatively flat. Moreover, both nonlinear coefficient and model filed
distribution were simulated, respectively.
A novel passive optical network (PON) over optical code division multiple access (OCDMA) uplink based on the
differential quadrature reference phase shift keying (DQPSK)/ on-off Keying (OOK) orthogonal re-modulation and time
domain phase coherent OCDMA en/decoder scheme has been proposed. The bit error rate and receiver sensitivity of the
system have been investigated, and the security performance and MAI (Multi Access Interference) property of the
OCDMA uplink data have also been investigated. The results show that the proposed PON system is more cost-effective
with less power penalty, and the capacity and security of upstream data can be greatly improved .