Koen Huybrechts

Fast all-optical flip-flop based on a single distributed feedback laser diode

Since there is an increasing demand for fast networks and switches, the electronic data processing imposes a severe bottleneck and all-optical processing techniques will be required in the future. All-optical flip-flops are one of the key components because they can act as temporary memory elements. Several designs have already been demonstrated but they are often relatively slow or complex to fabricate. We demonstrate experimentally fast flip-flop operation in a single DFB laser diode which is one of the standard elements in todays telecommunication industry. Injecting continuous wave light in the laser diode, a bistability is obtained due to the spatial hole burning effect. We can switch between the two states by using pulses with energies below 200 fJ resulting in flip-flop operation with switching times below 75 ps and repetition rates of up to 2 GHz.

Proposal for an All-Optical Flip-Flop Using a Single Distributed Feedback Laser Diode

We introduce a new concept for an all-optical flip-flop based on a single distributed feedback laser. The injection of external light into the laser results in a nonuniform carrier distribution. We will show numerically that this nonlinear effect of the carriers gives rise to a bistability that can be exploited for fast flip-flop operation.

All-Optical Flip-Flop Operation in a Standard Tunable DBR Laser Diode

A novel concept for all-optical flip-flop operation in a distributed Bragg reflector laser is presented. Using pulses at the same wavelength but with a different duration and amplitude, flip-flop operation is obtained experimentally with switching times of 50 ps and pulse energies of 2-4 pJ.

40-Gb/s All-Optical Packet Switching With a Distributed-Feedback Laser as All-Optical Flip-Flop

All-optical flip-flops (AOFFs) have recently received increased attention as elements for all-optical packet-switched networks. In this letter, we use a single off-the-shelf distributed- feedback laser as AOFF to switch 40-Gb/s packets with a guard time as low as 150 ps.

All-Optical 2R Regeneration Using the Hysteresis in a Distributed Feedback Laser Diode

A broadband optical 2R regenerator based on a single distributed feedback laser is demonstrated for nonreturn to zero signals at a bitrate of 10 Gb/s. A semi-analytical approach for the influence of hysteresis on the transfer function of a 2R regenerator is shown.

Nonlinear dynamics of asymmetrically coupled microdisk lasers

The operating regimes of coupled microdisk lasers are investigated using rate equation modeling. We found that unidirectional operation is possible for smaller currents than for single disks. However, we also found regimes of chaos.

Fast 40 Gb/s optical packet switching using an all-optical flip-flop based on a single distributed feedback laser

Fast all-optical switching of 40 Gb/s packets is demonstrated using a single off-the shelf DFB laser as all-optical flip-flop, thus offering a fast (150 ps) and economically viable method to implement a transparent network node.

Numerical and experimental study of the switching times and energies of DFB-laser based all-optical flip-flops

We report on the switching times and energies of a DFB all-optical flip-flop and their dependence on device and operating parameters. Numerical as well as experimental results are discussed.

Fast operation of a broadband all-optical flip-flop based on a single DFB-laser diode

We demonstrate an all-optical flip-flop based on a single DFB-laser diode with repetition rates up to 2 GHz, set/reset-pulses of 7 ps and 200 fJ, a switch-on time of 75 ps and a switch-off time below 20 ps.

Heterogeneously integrated microdisk lasers for optical interconnects and optical logic

Optical interconnect and optical packet switching systems could take advantage of small footprint, low power lasers and optical logic elements. Microdisk lasers, with a diameter below 10μm and fabricated in InP membranes with a high index contrast, offer this possibility at the telecom wavelengths. The lasers are fabricated using heterogeneous integration of InP membranes on silicon-on-insulator (SOI) passive waveguide circuits, which allows to combine the active elements with compact, high-index contrast passive elements. The lasing mode in such microdisk lasers is a whispering gallery mode, which can be either in the clockwise (CW) or counter clockwise direction (CCW) or in both. The coupling to the SOI wire waveguides is through evanescent coupling. Predefined, unidirectional operation can be achieved by terminating the SOI wires at one end with Bragg gratings. For all-optical flip-flops, the laser operation must be switchable between CW and CCW, using short optical pulses. Unidirectional operation in either direction is only possible if the coupling between CW and CCW direction is very small, requiring small sidewall surface roughness, and if the gain suppression is sufficiently large, requiring large internal power levels. All-optical flip-flops based on microdisk lasers with diameter of 7.5μm have been demonstrated. They operate with a CW power consumption of a few mW and switch in 60ps with switching energies as low as 1.8fJ. Operation as all-optical gate has also been demonstrated. The surface roughness is limited through optimized etching of the disks and the large internal power is obtained through good heat sink.