Ch. Kouloumentas

All-Fiberized Dispersion-Managed Multichannel Regeneration at 43 Gb/s

We report on the simultaneous 2R regeneration of up to three 42.7-Gb/s wavelength-division-multiplexing channels in a simple dispersion-managed fiber section with signal quality improvements higher than 1.7 dB. The regenerator relies on self-phase modulation-induced spectral broadening of the optical channels inside the fiber section and subsequent bandpass filtering at shifted wavelengths, and it is experimentally investigated in single-, dual-, and three-channel operation using optical pulses of 33% duty cycle.

Clock Recovery at 160 Gb/s and Beyond, Using a Fiber-Based Optical Power Limiter

We propose a simple all-optical clock recovery technique for short data packets at 160 Gb/s, and beyond, which is based on the concept of using a Fabry-Peacuterot filter (FPF). The novel feature of the technique is the use of a highly nonlinear fiber followed by an optical bandpass filter, centered at the initial carrier wavelength, which acts as an ultrafast power limiter, removing drastically the amplitude modulation of the FPFs output and providing the clock signal

Complex monolithic and InP hybrid integration on high bandwidth electro-optic polymer platform.

We report on the monolithic integration of multimode interference couplers, Bragg gratings, and delay-line interferometers on an electro-optic polymer platform capable of modulation directly at 100 Gb/s. We also report on the hybrid integration of InP active components with the polymer structure using the butt-coupling technique. Combining the passive and the active components, we demonstrate a polymer-based, external cavity laser with 17 nm tuning range and the optical assembly of an integrated 100 Gb/s transmitter, and we reveal the potential of the electro-optic polymer technology to provide the next generation integration platform for complex, ultra-high-speed optical transceivers.

Tunable 100 Gbaud Transmitter Based on Hybrid Polymer-to-Polymer Integration for Flexible Optical Interconnects

We introduce a hybrid integration platform based on the combination of passive and electro-optic polymers. We analyze the optical and physical compatibility of these materials and describe the advantages that our hybrid platform is expected to have for the development of transmitters in terms of operation flexibility and speed. We combine our platform with InP electronics and develop a transmitter with 22-nm tunability in the C-band and potential for serial non-return-to-zero on-off-keying operation directly at 100 Gb/s. We investigate its transmission performance at 80 and 100 Gb/s using dispersion uncompensated standard single-mode fiber and demonstrate bit-error rate (BER) lower than 10-10 at 80 Gb/s after 1625 m, lower than 10-10 at 100 Gb/s after 500 m, lower than 10-9 at 100 Gb/s after 1000 m, and BER 10-7 at the same rate after 1625 m. We also employ the transmitter inside an experimental setup, which aims to emulate an optical circuit switched (OCS) domain of an intradata center network, and demonstrate at 100 Gb/s the way, in which its wavelength tunability can resolve contentions and improve the flexibility and the efficiency of the network. Finally, we outline our next plans, including the development of flexible and ultra-fast transmitters for coherent systems using the same polymer-to-polymer integration platform.

Packet clock recovery using a bismuth oxide fiber-based optical power limiter

We demonstrate an optical clock recovery circuit that extracts the line rate component on a per packet basis from short data packets at 40Gb/s. The circuit comprises a Fabry-Perot filter followed by a novel power limiting configuration, which in turn consists of a 5m highly nonlinear bismuth oxide fiber in cascade with an optical bandpass filter. Both experimental and simulation-based results are in close agreement and reveal that the proposed circuit acquires the timing information within only a small number of bits, yielding a packet clock for every respective data packet. Moreover, we investigate theoretically the scaling laws for the parameters of the circuit for operation beyond 40 Gb/s and present simulation results showing successful packet clock extraction for 160 Gb/s data packets. Finally, the circuits potential for operation at 320 Gb/s is discussed, indicating that ultrafast packet clock recovery should be in principle feasible by exploiting the passive structure of the device and the fsec-scale nonlinear response of the optical fiber.

Multi-Flow Transmitter Based on Polarization and Optical Carrier Management on Optical Polymers

We propose a novel multi-flow transmitter concept capable of controlling the number, type, wavelength, and destination of the generated optical flows depending on the client traffic. The concept is based on the selection of the number of optical carriers per flow and the selection between single- and dual-polarization flows. We demonstrate the proof-of-concept combining two commercial In-Phase/Quadrature (IQ) modulators with two prototype polymer circuits, which integrate three tunable lasers for flexible wavelength allocation, four thermo-optic switches for flexible optical routing on-chip, and elements for polarization handling on-chip. We incorporate this transmitter inside an optical node, and we investigate one-flow scenarios with dual-carrier or dual-polarization quadrature phase shift keying (QPSK) modulation, and two-flow scenarios based on two independent QPSK signals. The transmitter and node configuration are controlled by a software-defined optics platform. We demonstrate dynamic operation at 28 GBd and error-free coherent transmission over 100 km of the standard single-mode fiber.

Multi-format all-optical processing based on a large-scale, hybridly integrated photonic circuit

We investigate through numerical studies and experiments the performance of a large scale, silica-on-silicon photonic integrated circuit for multi-format regeneration and wavelength-conversion. The circuit encompasses a monolithically integrated array of four SOAs inside two parallel Mach-Zehnder structures, four delay interferometers and a large number of silica waveguides and couplers. Exploiting phase-incoherent techniques, the circuit is capable of processing OOK signals at variable bit rates, DPSK signals at 22 or 44 Gb/s and DQPSK signals at 44 Gbaud. Simulation studies reveal the wavelength-conversion potential of the circuit with enhanced regenerative capabilities for OOK and DPSK modulation formats and acceptable quality degradation for DQPSK format. Regeneration of 22 Gb/s OOK signals with amplified spontaneous emission (ASE) noise and DPSK data signals degraded with amplitude, phase and ASE noise is experimentally validated demonstrating a power penalty improvement up to 1.5 dB.

Simultaneous processing of 43 Gb/s WDM channels by a fiber-based dispersion-managed 2R regenerator

We demonstrate 43 Gb/s multi-channel 2R regeneration in a single dispersion-managed fiber, based on SPM-induced spectral broadening and subsequent offset filtering.

Passive and electro-optic polymer photonics and InP electronics integration

Hybrid photonic integration allows individual components to be developed at their best-suited material platforms without sacrificing the overall performance. In the past few years a polymer-enabled hybrid integration platform has been established, comprising 1) EO polymers for constructing low-complexity and low-cost Mach-Zehnder modulators (MZMs) with extremely high modulation bandwidth; 2) InP components for light sources, detectors, and high-speed electronics including MUX drivers and DEMUX circuits; 3) Ceramic (AIN) RF board that links the electronic signals within the package. On this platform, advanced optoelectronic modules have been demonstrated, including serial 100 Gb/s [1] and 2x100 Gb/s [2] optical transmitters, but also 400 Gb/s optoelectronic interfaces for intra-data center networks [3]. To expand the device functionalities to an unprecedented level and at the same time improve the integration compatibility with diversified active / passive photonic components, we have added a passive polymer-based photonic board (polyboard) as the 4th material system. This passive polyboard allows for low-cost fabrication of single-mode waveguide networks, enables fast and convenient integration of various thin-film elements (TFEs) to control the light polarization, and provides efficient thermo-optic elements (TOEs) for wavelength tuning, light amplitude regulation and light-path switching.

Agile photonic integrated systems-on-chip enabling WDM terabit networks

The ICT-APACHE research project is focusing on the development of cost-effective, compact, scalable and agile integrated components capable of generating, regenerating and receiving multi-level encoded data signals for high capacity (>100 Gb/s) WDM optical networks. APACHE technology relies on InP active, monolithic chips, hybridly integrated on silica-on-silicon planar lightwave platforms in order to achieve cost-efficiency, high yield, low power consumption and device scaling beyond the level commercially available today. The APACHE integration approach is implemented in a two-dimensional plan, horizontally and vertically, in order to enable multi-functionality and increased capacity, respectively. The final goal of the APACHE project is the fabrication of integrated arrays of transmitters, receivers and regenerators that will operate with 100 Gb/s OOK, DPSK and DQPSK modulated signals, allowing for 1 Terabit/s on-chip capacity. In this paper, we will review the latest results from the system-level characterization of the developed components and will outline the roadmap for future endeavours.