Monolithic 16-wavelength selector based on a chain of passband-flattened cyclic AWGs and optical switches.

An InP monolithically integrated wavelength selector based on combinations of integrated AWGs and SOAs selects one out of up to 16 input channels. Loss-compensated, error-free WDM channel selection operation with <2.3 dB penalties is reported, with an OSNR of up to 32.5 dB/0.1 nm.

Numerical and experimental study of a high port-density WDM optical packet switch architecture for data centers.

Data centers have to sustain the rapid growth of data traffic due to the increasing demand of bandwidth-hungry internet services. The current intra-data center fat tree topology causes communication bottlenecks in the server interaction process, power-hungry O-E-O conversions that limit the minimum latency and the power efficiency of these systems. In this paper we numerically and experimentally investigate an optical packet switch architecture with modular structure and highly distributed control that allow configuration times in the order of nanoseconds. Numerical results indicate that the candidate architecture scaled over 4000 ports, provides an overall throughput over 50 Tb/s and a packet loss rate below 10(-6) while assuring sub-microsecond latency. We present experimental results that demonstrate the feasibility of a 16x16 optical packet switch based on parallel 1x4 integrated optical cross-connect modules. Error-free operations can be achieved with 4 dB penalty while the overall energy consumption is of 66 pJ/b. Based on those results, we discuss feasibility to scale the architecture to a much larger port count.

Passive InP regenerator integrated on SOI for the support of broadband silicon modulators.

Passive signal regeneration based on the Membrane InP Switch (MIPS) is demonstrated. Because of the high confinement of light in the active region of the MIPS, the device acts as a saturable absorber with a highly non-linear response. Using this effect, the extinction ratio (ER) of low-ER signals can be tripled and a receiver sensitivity enhancement of 4.5dB is demonstrated using an input signal at 1Gb/s with an ER of 2dB. Regenerator operation up to 5Gb/s is demonstrated and using a device simulator a strategy to reach higher bitrate operation is proposed.

Optical switching and detection of 640 Gbits/s optical time-division multiplexed data packets transmitted over 50 km of fiber.

We demonstrate 1×4 optical-packet switching with error-free transmission of 640 Gbits/s single-wavelength optical time-division multiplexed data packets including clock distribution and short pulse generation for optical time demultiplexing based on a cavityless pulse source.

Bias-free, low power and optically driven membrane InP switch on SOI for remotely configurable photonic packet switches.

A small footprint integrated Membrane InP Switch (MIPS) on Silicon-On-Insulator (SOI) is demonstrated for use in all-optical packet switching. The device consists of an optically pumped III-V membrane waveguide of only 100 nm thick, coupled to the underlying SOI waveguide circuit. Because of its limited thickness, the optical confinement in the active layers is maximized, allowing for high extinction ratio of over 30 dB when applying a low power optical pump signal, over the entire C-band. The switch has 400/1300 ps on/off switching times and no measurable pattern dependence or switching related power penalties for a bitrate up to 40 Gb/s, using a switching power of only 2 dBm.

Enhanced 40 and 80 Gb/s wavelength conversion using a rectangular shaped optical filter for both red and blue spectral slicing.

By using a tunable filter with tunability of both bandwidth and wavelength and a very sharp filter roll-off, considerable improvement of all optical Wavelength Conversion, based on Cross Gain and Phase Modulation effects in a Semiconductor Optical Amplifier and spectral slicing, is shown. At 40 Gb/s slicing of blue spectral components is shown to result in a small penalty of 0.7 dB, with a minimal eye broadening, and at 80 Gb/s the low demonstrated 0.5 dB penalty is a dramatic improvement over previously reported wavelength converters using the same principal. Additionally, we give for the first time quantitative results for the case of red spectral slicing at 40 Gb/s which we found to have only 0.5 dB penalty and a narrower time response, as anticipated by previously published theoretical papers. Numerical simulations for the dependence of the eye opening on the filter characteristics highlight the importance of the combination of a sharp filter roll-off and a broad passband.

All-optical demultiplexing of 640 to 40 Gbits/s using filtered chirp of a semiconductor optical amplifier.

We present a high-capacity ultrafast all-optical time demultiplexer that can be employed to retrieve 40 gigabits/second (Gb/s) base-rate channels from a 640 Gb/s single-polarized signal. The demultiplexer utilizes ultrafast effects of filtered chirp of a semiconductor optical amplifier. Excellent demultiplexing performance is shown at very low switching powers: +8 dBm (640 Gb/s data) and -14 dBm (40 GHz clock). The demultiplexer has a simple structure and, in principle, allows monolithic integration.

An optical threshold function based on polarization rotation in a single semiconductor optical amplifier.

Optical threshold functions are a basic building block for all-optical signal processing, and this paper investigates a threshold function design reliant on a single active element. An optical threshold function based on nonlinear polarization rotation in a single semiconductor optical amplifier is proposed. It functions due to an induced modification of the birefringence of a semiconductor optical amplifier caused by an externally injected optical control signal. It is shown that switching from both the TE to the TM mode and vice versa is possible. The measured results are supported by simulation results based on the SOA rate equations.

Coupled Mach-Zehnder interferometer memory element.

Two active Mach-Zehnder interferometers are integrated in a monolithic InP/InGaAsP photonic integrated circuit. Together they form a crucial component for optical signal processing: an optical memory element or set-reset flip-flop. The switching time for this initial device is approximately 200 ps. The photonic integrated circuit contains active and passive optical components, including electro-optic phase shifters.

40 Gb/s all-optical packet clock recovery with ultrafast lock-in time and low inter-packet guardbands.

We demonstrate a 40 Gb/s self-synchronizing, all-optical packet clock recovery circuit designed for efficient packet-mode traffic. The circuit locks instantaneously and enables sub-nanosecond packet spacing due to thelow clock persistence time. A low-Q Fabry-Perot filter is used as a passive resonator tuned to the line-rate that generates a retimed clock-resembling signal. As a reshaping element, an optical power-limiting gate is incorporated to perform bitwise pulse equalization. Using two preamble bits, the clock is captured instantly and persists for the duration of the data packet increased by 16 bits. The performance of the circuit suggests its suitability for future all-optical packet-switched networks with reduced transmission overhead and fine network granularity.

SOA-based all-optical switch with subpicosecond full recovery.

We investigate all-optical switching in a multi-quantum-well semiconductor optical amplifier-based nonlinear polarization switch using optical pulses with duration of 200 fs at a central wavelength of 1520 nm. We show full recovery of the switch within 600 fs, in both the gain and absorption regime. We discuss the switching and recovery mechanisms using numerical simulations that are in qualitatively good agreement with our experimental data.

Optical shift register based on an optical flip-flop memory with a single active element.

We present an optical shift register that consist out of two serially connected optical flip-flop memories driven by common clock pulses. Each optical flip-flop consists out of two ring lasers sharing a single active element, which makes the optical flip-flops easily cascade with each other. The two cascaded optical flip-flops are controlled by the clock pulses in such a way that the input data set the new state of the first optical flipflop, after the state of the first flip-flop has been transferred to the second optical flip-flop. The concept is demonstrated at an operation speed of 20 kHz, which is limited by the 10 m long laser cavities formed by the fiber pig-tailed components.

Sub-picosecond pulse generation employing an SOA-based nonlinear polarization switch in a ring cavity.

We demonstrate the generation of sub-picosecond optical pulses using a semiconductor optical amplifier (SOA) and a linear polarizer placed in a ring-laser configuration. Nonlinear polarization rotation in the SOA serves as the passive mode-locking mechanism. The ring cavity generates pulses with duration below 800 fs (FWHM) at a repetition rate of 14 MHz. The time -bandwidth product is 0.48. Simulation results in good agreement with the experimental results are presented.

Asynchronous, self-controlled, all-optical label and payload separator using nonlinear polarization rotation in a semiconductor optical amplifier.

We demonstrate an all-optical label and payload separator based on nonlinear polarization rotation in a semiconductor optical amplifier (SOA). The proposed scheme uses a packet format composed of a label and payload information signal combined with a control signal by using polarization division multiplexing. The control signal is employed to separate the label from the payload signal by exploiting nonlinear polarization rotation in a SOA. Experimental results show a label from payload suppression factor of 22 dB. This scheme operates asynchronously and does not need external control signal. Clean and wide open eye diagrams are obtained for both the payload and the label signal operating at bit-rates of 10 Gbit/s and 625 Mbit/s, respectively.

Carrier recovery time in semiconductor optical amplifiers that employ holding beams.

An analytical expression for the carrier recovery time in semiconductor optical amplifiers (SOAs) that employ holding beams is presented. The amplifier model from which the expression is derived assumes a uniform carrier density along the SOA's length and that the signal and the holding beams both receive amplification. Simulations and experiments show that the expression predicts the recovery time well over a wide range of amplifier gains, holding beam powers, and configurations.

All fiber-optic neural network using coupled SOA based ring lasers.

An all-optical neural network is presented that is based on coupled lasers. Each laser in the network lases at a distinct wavelength, representing one neuron. The network status is determined by the wavelength of the network's light output. Inputs to the network are in the optical power domain. The nonlinear threshold function required for neural-network operation is achieved optically by interaction between the lasers. The behavior of the coupled lasers is explained by a simple laser model developed in the paper. In particular, the winner take all (WTA) neural-network behavior of a system of many lasers is described. An experimental system is implemented using single mode fiber optic components at wavelengths near 1550 nm. A number of functions are implemented to demonstrate the practicality of the new network. The neural network is particularly robust against input wavelength variations.