Fiber-based Loop Mirror Research Articles

Self-Clocked All-Optical Add/Drop Multiplexer for Asynchronous CDMA Ring Networks

In this paper, we demonstrate a novel self-clocked code-drop unit for incoherent optical code-division multiple-access (CDMA) networks. The unit is based on an all-optical thresholder with internal wavelength conversion that creates a control signal for the drop gate from the incoming data stream. This architecture does not require an external clock signal for drop operation and can be used in asynchronous ring networks. The proposed unit is experimentally demonstrated for two-dimensional time-wavelength optical CDMA codes at a bit rate of 2.5 Gbit/s with two different types of drop gates: terahertz optical asymmetric multiplexer and nonlinear fiber-based loop mirror. Error-free operation is achieved in both configurations. The development of a self-clocked add/drop multiplexer demonstrates a novel concept of asynchronous node operation in multiple access networks.

A standard fiber-based loop mirror as a gain-flattening filter for erbium-doped fiber amplifiers

We report flattening of the amplified spontaneous emission (ASE) spectrum from an erbium-doped fiber (EDF) using a standard fiber-based loop mirror (FLM), realized with an "over-coupled" fiber coupler. Through simulation, a bend-induced birefringent FLM as a gain-flattening filter is designed. Subsequently, an over-coupled coupler with a free spectral range of 140 nm is fabricated to realize the FLM, which is integrated to an EDF that is pumped by a 980-nm laser diode. By introducing an appropriate amount of bend-induced birefringence in the loop, the ASE spectrum of the EDF could be flattened within /spl plusmn/0.5 dB over a wavelength range of 32 nm in the C-band.