Andrea Trita

Dynamic operation of all-optical Flip-Flop based on a monolithic semiconductor ring laser

A monolithic semiconductor ring laser (SRL) is demonstrated as a fully all-optical flip-flop that can be triggered by optical pulses of 400 ps duration, showing 130 ps response time.

Simultaneous Interrogation of Multiple Fiber Bragg Grating Sensors Using an Arrayed Waveguide Grating Filter Fabricated in SOI Platform

A novel fiber Bragg grating (FBG) interrogator is demonstrated based on an optimized arrayed waveguide grating (AWG) filter. The AWG response is optimized to achieve large crosstalk between the output channels, which allows simultaneous detection of multiple FBG peaks, using centroid signal processing techniques, without constraints on the minimum FBG peak spectral width. The measured interrogator resolution is 2.5 pm, and the total measurement range is 50 nm. The device is fabricated in a silicon-on-insulator platform and has a footprint of only 2.2 × 1.5 mm. A novel approach to minimize the polarization dependence of the device is proposed and experimentally demonstrated.

All-Optical Toggle Flip-Flop Based on Monolithic Semiconductor Ring Laser

A novel monolithic all-optical flip-flop of the toggle type with two complementary outputs is demonstrated based on a semiconductor ring laser (SRL), where the intrinsic directional bistability of the SRL device is combined with the saturable absorption effect that takes place in the reverse-biased input waveguides. Toggle flip-flop (TFF) operation is experimentally demonstrated using optical trigger toggle pulses of 500 ps duration. The achieved bit-rate of 500 Mb/s is the highest reported so far for all-optical TFFs. The operational speed is limited by the carrier recovery time of the saturable absorbers; however, the proposed technology has potential for multi-gigabits per second operation.

All-Optical Directional Switching in Bistable Semiconductor-Ring Lasers

We investigate the operation of directionally bistable semiconductor-ring lasers as all-optical flip-flops. We demonstrate fast switching between the two lasing directions by injection of optical pulses acting as set and reset control signals with switching times as fast as 20 ps, delay times as short as 60 ps, and switching energy of 150 fJ.

Application of Brillouin-Based Continuously Tunable Optical Delay Line to Contention Resolution Between Asynchronous Optical Packets

A novel approach for resolution of contentions between asynchronous optical packets, exploiting a self-synchronizing mechanism by means of dynamic all-optical tunable delay line based on stimulated Brillouin scattering in fibers, is reported. Time delay between contending optical packets is mapped into the output timing of a contention-detecting pulse produced by the tunable delay line. The output pulse from the delay line triggers an integrated all-optical flip-flop that generates a synchronized gating signal driving a semiconductor-based all-optical switch, for low-priority packets deflection. Correct operation of the proposed scheme without bit loss or packet fragmentation is demonstrated, and error-free operation for the switched packets is reported under different cases of relative delay between incoming optical packets. The scheme operates entirely in the photonic domain and exploits integrated optical switches and a passive optical-delay line for minimized node latency. Extension to symmetric operation allowing priority swapping between the input packets is also proposed.

Design, integration, and testing of a compact FBG interrogator, based on an AWG spectrometer

Fiber Bragg Grating or FBG sensors are gaining more and more interest in structural health monitoring of composite materials. Often, the weakest point in such a system is the ingress point of the fiber sensing chain into the composite material. For this reason we have developed a strongly miniaturized FBG interrogator unit with wireless power and data transmission, which can be incorporated in the composite structure. The interrogator is based on an arrayed waveguide grating (AWG) filter fabricated in a SOI technology, which is tailored in such a way to give large cross-talk between neighboring channels. The AWG signals are read by a linear 128 pixel InGaAs array flip-chipped on top of the Photonic Circuit (PIC). The spectrometer unit is completed with a ROIC mounted on the same substrate. The SLED and remaining electronics are integrated on a small and thin substrate and surrounded by the wireless antenna. The interrogator has an overall dimension of 100 mm diameter by max 7 mm height. The power dissipation of the electronics unit is limited to 1.5 W. The unit is capable of measuring strain values as low as 5 micro-strain.

All-optical self-synchronizing scheme for contention resolution in asynchronous optical packet switched networks using continuously tunable optical delay line

Continuously tunable, optically-controlled variable delay line based on dynamic Brillouin grating is exploited for automated synchronization of switching signals in a network node, enabling asynchronous contention resolution with packet priorization.

All-optical Set-Reset Flip-Flop based on semiconductor ring laser: Ultrafast response and error-free Bit-Error-Rate operation

A monolithic semiconductor ring laser (SRL) operates as all-optical Flip-Flop. We report on ps-scale temporal response and Bit-Error-Rate experiments.

Time-domain response to ps optical pulse trigger of an all-optical flip-flop based on semiconductor ring laser

Monolithic Semiconductor Ring Lasers (SRLs) are promising devices for all-optical memory and all-optical switching applications, as they can operate in a directional bistable regime where only one directional mode (clockwise or anti-clockwise) is active at one time. The unidirectional bistable regime can be naturally associated to a binary logic, and the SRL represents an elementary digital memory cell that can be written all-optically, realising the function of an all-optical flip-flop. In fact, the direction of operation can be switched by injecting an external optical signal pulse into the SRL through one of the 4 input/output ports. Directional switching of the SRL-based all-optical flip-flop has been demonstrated by injecting optical pulses with 5 ps duration into one of the four input/output ports. The required switching energy is around 100 fJ, and the swiching time is between 100 and 200 ps. The same function has been demonstrated by injecting 400 ps pulses as optical trigger.

Monolithic All-Optical Set-Reset Flip-Flop Operating at 10 Gb/s

A monolithic semiconductor ring laser is operated as an all-optical set-reset flip-flop triggered by external optical pulses. Bit-error-rate measurements of set-reset switchings under the injection of a pseudo-random-bit-sequence have been performed, showing reliable operation up to 10 Gb/s.