J. De Merlier

Experimental demonstration of all-optical regeneration using an MMI-SOA

A novel all-optical 2R regenerator based on a multimode interference coupler (MMI) semiconductor optical amplifier is presented. Static measurements of the transfer function reveal a digital transfer characteristic and a high increase in extinction ratio. The experiments are in good agreement with simulations, which have been done using a modified beam propagation method program. The device has a high tolerance to the MMI length. It has been fabricated in an all-active layout, avoiding the need for active/passive integration and is very compact.

All-optical 2R regeneration based on polarization rotation in a linear optical amplifier

All-optical 2R-regeneration based on polarization rotation in a single semiconductor linear optical amplifier is experimentally demonstrated. An extinction ratio (ER) improvement of 15 dB has been obtained for an input ER of 5 dB under static operation. With a degraded input signal, a receiver-sensitivity improvement of >3 dB at a bit error rate of 10/sup -9/ was found for 2.5 Gb/s. Regenerative capability for 10 Gb/s has also been verified.

Dynamic birefringence of the linear optical amplifier and application in optical regeneration

Dynamic birefringence of the linear optical amplifier (LOA) is theoretically and experimentally investigated. Significant nonlinear variations of the state of polarization with the input power and bias current of the LOA have been found. Based on this nonlinear change of the state of polarization, an all-optical 2R regenerator is demonstrated. Under static operation, an extinction ratio (ER) improvement of 15 dB has been obtained for an input ER of 5 dB. With a degraded input signal, a receiver sensitivity improvement of over 3 dB at a bit-error rate (BER) of 10/sup -9/ has been found for 2.5 Gb/s. For 10 Gb/s, zero power penalty is observed. Significant improvements of ER for both 2.5 and 10 Gb/s are obtained.

Experimental demonstration of 15 dB extinction ratio improvement in a new 2R optical regenerator based on an MMI-SOA

All-optical regeneration has been demonstrated for the first time using a 2/spl times/2 MMI-SOA, showing a digital-like transfer characteristic and an output extinction ratio of 22 dB for an input extinction ratio of 7 dB.

A novel 2R regenerator based on an asymmetric Mach-Zehnder interferometer incorporating an MMI-SOA

We propose a novel type of 2R regenerator, based on a Mach-Zehnder interferometer (MZI) with an SOA in one arm and a multi-mode-interference-coupler (MMI)-SOA in the other arm, which shows an improved regeneration characteristic compared to interferometers with 2 identical SOAs. The experimental results agree very well with the simulations. The measured static transfer function shows a digital form and a large increase in extinction ratio. An input extinction ratio of 6 dB can be improved to over 20 dB.

Elimination of crosstalk in the common output amplifier of a multi-wavelength source by gain clamping

We realized a multiwavelength laser using a hybrid integration technology. Simultaneous laser operation of four wavelength channels could be obtained. To avoid signal cross talk, a novel approach to clamp the gain of the common amplifier is demonstrated.

Amplified spontaneous emission in index-guided multimodal waveguide structures

This paper describes a theory of amplified spontaneous emission in index-guided multimodal waveguide structures. It is based on a perturbation approach taking into account the correlated excitation of the different guided modes of the unperturbed waveguide. The coupling between these modes due to the propagation through a perturbed waveguide is taken into account by deducing evolution equations of the cross correlations between the modal amplitudes. Eventually, a beam propagation method program, including the spontaneous emission model, has been used for a comparison of the noise characteristics of a single-mode SOA with a 1-by-1 multimode interference semiconductor optical amplifier. Experiments have been performed confirming the obtained simulation results.

Demonstration of multi-wavelength laser with a gain-clamped output amplifier

We proposed a new approach to reduce the thermal crosstalk problem and to avoid crosstalk in the output amplifier of a multi-wavelength laser based on the gain-clamping principle. The device was realised, using the hybrid coupling technique, and the gain-clamping was experimentally verified.

The influence of lateral carrier diffusion and surface recombination on the behavior of semiconductor optical amplifier (SOA)-based MMIs

The influence of lateral carrier diffusion and surface recombination on the self-imaging properties of semiconductor-optical-amplifier-based multimode interference couplers has been verified by simulations using a beam propagation method. It shows a significant degradation of the self-imaging properties of these devices. Buried heterostructures or deeply etched waveguide structures can decrease the impact when the degree of surface recombination is sufficiently low.

Interferometric photonic circuits for 2R optical regeneration

This paper discusses two types of 2R all-optical signal regenerators. Both types can be fabricated as photonic integrated circuits that can exhibit very good static regeneration characteristics. More research is needed to optimise the regenerators for operation at high speed.