Frans Huijskens

Optical packet switching and buffering by using all-optical signal processing methods

We present a 1 /spl times/ 2 all-optical packet switch. All the processing of the header information is carried out in the optical domain. The optical headers are recognized by employing the two-pulse correlation principle in a semiconductor laser amplifier in loop optical mirror (SLALOM) configuration. The processed header information is stored in an optical flip-flop memory that is based on a symmetric configuration of two coupled lasers. The optical flip-flop memory drives a wavelength routing switch that is based on cross-gain modulation in a semiconductor optical amplifier. We also present an alternative optical packet routing concept that can be used for all-optical buffering of data packets. In this case, an optical threshold function that is based on a asymmetric configuration of two coupled lasers is used to drive a wavelength routing switch. Experimental results are presented for both the 1 /spl times/ 2 optical packet switch and the optical buffer switch.

Optical signal processing based on self-induced polarization rotation in a semiconductor optical amplifier

We demonstrate novel optical signal processing functions based on self-induced nonlinear polarization rotation in a semiconductor optical amplifier (SOA). Numerical and experimental results are presented, which demonstrate that a nonlinear polarization switch can be employed to achieve all-optical logic. We demonstrate an all-optical header processing system, an all-optical seed pulse generator for packet synchronization, and an all-optical arbiter that can be employed for optical buffering at a bit rate of 10 Gb/s. Experimental results indicate that optical signal processing functions based on self-polarization rotation have a higher extinction ratio and a lower power operation compared with similar functions based on self-phase modulation.

Design Considerations for a Transparent Mode Group Diversity Multiplexing Link

Mode group diversity multiplexing (MGDM) is an optical multiple-input-multiple-output technique that aims at creating independent communication channels over a multimode fiber, using subsets of propagating modes. This letter deals with the analysis of an MGDM point-to-point link, transparent to the transmission format. The geometry of a mode-group selective multi/demultiplexer is optimized in order to minimize the crosstalk among the channels. The power penalty is calculated when a zero-forcing algorithm is used to mitigate the crosstalk

High-Bit-Rate Dynamically Reconfigurable WDM–TDM Access Network

The intensification of traffic in the access network requires the development of novel architectural solutions for a reconfigurable network topology and components based on optical technologies. We present a hybrid ring-shaped wavelength division multiplexing (WDM)-time division multiplexing (TDM) passive optical network (PON) that is capable of providing bandwidth on demand at high bit rates in a transparent and dynamic manner. Our cost-efficient and scalable network architecture is based on integratable components such as a wavelength-agile optical networking unit and a microring-resonator-based remote node. An appropriately modified control layer is introduced to manage the network. We also discuss the implementation of optical codes instead of time slots to take the step toward optical code division multiplexing (OCDM) WDM PONs that relieve the network of strict time scheduling of traffic and ranging. Therefore, an additional reduction of complexity in network management, improvement of network scalability, and a guarantee of fully symmetric traffic are foreseen for every user. Finally, we show a scenario for smooth migration from existing PON solutions to our WDM-TDM PON architecture.

Hybrid Integrated, All-optical Flip-flop Memory Element for Optical Packet Networks

We describe a novel, fully-packaged, hybrid-integrated all-optical flip-flop memory element. Static state contrast ratios of 10dB and 13dB are demonstrated and the flip-flop can have its state changed dynamically every 32ns with the introduction of state-setting pulses (pulse widths ≪150ps).

1.25-Gb/s Transmission Over an Access Network Link With Tunable OADM and a Reflective SOA

The emerging broadband services and the avalanche-like growth of the broadband subscribers result in the intensification of data traffic in access networks. This drives the development of last-mile technologies to support multiservice provision on high bit-rate-capable reconfigurable networks. In this letter, we present the first transmission experiments carried out on the testbed of a hybrid wavelength-division-multiplexing/time- division-multiplexing access network based on cost-efficient elements like an integrated optical add-drop multiplexer and a reflective semiconductor optical amplifier. We successfully transmit two 1.25-Gb/s wavelength channels over 26-km standard single-mode fiber carrying data to and from the user.

Employing Prism-Based Three-Spot Mode Couplers for High Capacity MDM/WDM Transmission

Based on a three-surface prism, a free space design of the three-spot mode coupler, supporting LP01 and LP11 modes, is introduced in this letter. We demonstrate 7.68 Tbit/s transmission of three mode division multiplexing (MDM) × 8 wavelength division multiplexing (WDM) × 320-Gb/s dual-polarization (DP)-32QAM over a 120 km differential-group-delay (DGD)-compensated few-mode fiber (FMF) by employing the proposed spot couplers.

10 Spatial mode transmission using low differential mode delay 6-LP fiber using all-fiber photonic lanterns.

To unlock the cost benefits of space division multiplexing transmission systems, higher spatial multiplicity is required. Here, we investigate a potential route to increasing the number of spatial mode channels within a single core few-mode fiber. Key for longer transmission distances and low computational complexity is the fabrication of fibers with low differential mode group delays. As such in this work, we combine wavelength and mode-division multiplexed transmission over a 4.45 km low-DMGD 6-LP-mode fiber by employing low-loss all-fiber 10-port photonic lanterns to couple light in and out of the fiber. Hence, a minimum DMGD of 0.2 ns (maximum 0.357 ns) is measured after 4.45 km. Instrumental to the multi-mode transmission system is the employed time-domain-SDM receiver, allowing 10 spatial mode channels (over both polarizations) to be captured using only 3 coherent receivers and real-time oscilloscopes in comparison with 10 for conventional methods. The spatial channels were unraveled using 20 × 20 multiple-input multiple-output digital signal processing. By employing a novel round-robin encoding technique, stable performance over a long measurement period demonstrates the feasibility of 10x increase in single-core multi-mode transmission.

All-optical signal processing for optical packet switching

Feature Issue on Optical Interconnection Networks (OIN). We present three optical signal processing functional blocks that enable 1×N optical packet switching. An ultrafast asynchronous multioutput all-optical header processor is demonstrated with a terahertz optical asymmetric demultiplexer in combination with a header preprocessor. It is shown that self-induced polarization rotation can be used for both the header processor and the header preprocessor. The second functional block is optical buffering. This is shown with both a laser neural network and a recirculating buffer. Related to this is a three-state all-optical memory based on coupled lasers, which increases the number of possible output states of an optical packet switch.

Toward multi-Gbps indoor optical wireless multicasting system employing passive diffractive optics

This Letter presents the evaluation and demonstration of an optical free-space (FS) multicasting system for multi-Gigabits-per-second (multi-Gbps) indoor transmission. These simultaneous line-of-sight links are formed by infrared beams and are beam-steered using a passive diffraction grating. The experiment has resulted in error-free links (bit error rate <10(-9) at 2.5 Gbps on-off keying) and is scalable to support higher data rates. This system is proposed for short-range optical wireless communication and can be seamlessly integrated in in-building fiber networks.