Alvaro moscoso-martir

RWTH Aachen University · Integrated Photonics Laboratory

We present a highly scalable PIC-based nonlinear frequency division multiplexed transmission system in which b-modulated channels are wavelength division multiplexed with spectral overlap so as to obtain a seamless spectrum without frequency guard bands.

We demonstrate a silicon photonic transmitter for soliton-based communications enabling the interleaving of QPSK and APSK modulated soliton pulses overlapping in both the time and frequency domains. The nonlinear Fourier transform is used to both determine adequate soliton launch conditions and facilitate nonlinear equalization at the receiver. A s...

We present optimized hourglass-shaped resonator CROW filters showing an improved power consumption of up to 30% when compared with standard circular ring shapes. Metal and doped waveguide heaters are compared in terms of efficiency, crosstalk and insertion losses.

We demonstrate a silicon photonics transmitter capable of modulating and optically merging solitons with reduced electronic constraints. Transmission over 3800 km and 5400 km has been experimentally shown for 2 Vpp and 4 Vpp drive voltages, respectively, without significant penalties between 2-channel and 4-channel configurations. Introduction The...

Electrical-optical signal processing has been shown to be a promising path to overcome the limitations of state-of-the-art all-electrical data converters. In addition to ultra-broadband signal processing, it allows leveraging ultra-low jitter mode-locked lasers and thus increasing the aperture jitter limited effective number of bits at high analog...

We experimentally demonstrate a silicon-photonics transmitter capable of modulating and optically merging solitons with different frequency and time spacing based on the nonlinear Fourier-transform, offloading electronics. Two soliton channels successfully transmit up to 5000 km.

We introduce an analytical model describing the statistical and spectral properties of laser phase noise induced intensity noise in ring-resonator-based modulation. The model is validated with single sideband orthogonal frequency division multiplexing (SSB-OFDM) implemented with a silicon photonics resonantly-assisted Mach-Zehnder modulator (RA-MZM...

We investigate the transmission of densely multiplexed solitons using a photonic integrated chip and the nonlinear Fourier-transform and analyze required launch conditions, the effect of (de-)multiplexing and noise on the nonlinear spectrum, and equalization techniques that can be used to enhance the transmission performance.

We analyze the implementation and capabilities of a silicon photonics transmitter capable of modulating and multiplexing groups of four solitons with different frequency and time spacing based on the nonlinear Fourier transform.

Semiconductor mode-locked lasers can be used in a variety of applications ranging from multi-carrier sources for WDM communication systems to time base references for metrology systems. Their packaging in compact chip- or module-level systems remains however burdened by their strong sensitivity to back-reflections, quickly destroying the coherence...

We demonstrate the possibility to densely multiplex solitons in time and frequency domain utilizing integrated silicon photonics and the Nonlinear Fourier Transform to transmit a fourth order soliton over multiple spans using lumped amplification.

We describe a resonantly enhanced Mach-Zehnder modulator (MZM) that can be operated over a wide temperature range of 55C without being actively biased, while providing a significant resonant enhancement of 6.8 at the nominal wavelength / temperature compared to a linear MZM driven with a distributed driver. More importantly, it enables a ~20X impro...

Semiconductor mode-locked lasers can be used in a variety of applications ranging from multi-carrier sources for WDM communication systems to time base references for metrology systems. Their packaging in compact chip- or module-level systems remains however burdened by their strong sensitivity to back-reflections, quickly destroying the coherence...

We report on the monolithic integration of a new class of reflown silica microtoroid resonators with silicon nanowaveguides fabricated on top of the silica film. Connectivity with other silicon photonics devices is enabled by inversion of the toroid geometry, defined by etching a circular opening rather than a disk in an undercut silica membrane. I...

We demonstrate an integrated 8 by 14 Gbps dense wavelength division multiplexed silicon photonics transceiver that makes use of an external mode-locked laser as a light source and a single semiconductor optical amplifier for post-modulation signal amplification. Remaining components necessary for modulation, filtering and (de‑)multiplexing are mono...

We present wideband and large free spectral range optical filters with steep passband edges for the selection of adjacent WDM communication channels that can be reliably fabricated with mainstream silicon photonics technology. The devices are based on three cascaded stages of coupled resonator optical waveguides loaded on a common bus waveguide. Th...

We derive compact equations describing the modification of amplified spontaneous emission signal beat noise arising from optical and electrical filtering in optically preamplified direct detection receivers. In particular, we show that this modification typically results in a further decrease of the signal quality factor. This is particularly prono...

We experimentally investigate an optical link relying on silicon photonics transmitter and receiver components as well as a single section semiconductor mode-locked laser as a light source and a semiconductor optical amplifier for signal amplification. A transmitter based on a silicon photonics resonant ring modulator, an external single section mo...

We demonstrate a complete Silicon Photonics WDM link relying on a single section semiconductor mode-locked laser and a single SOA to support up to 12 multiplexed channels with a bit error rate of 1e-12 at serial data rates of 14 Gbps without channel pre-emphasis, equalization or forward error correction. Individual channels reach error free operati...

We present a novel resonant Mach–Zehnder modulator whose arms are each loaded with five identical resonators. Size and power consumption are aggressively reduced compared to conventional modulators based on linear phase shifters. At the same time, a large optical bandwidth of 3.8 nm is maintained. We experimentally demonstrate open eye diagrams at...

Siliconphotonics modulators based on carrier depletion are a promising approach for optical interconnects due to their outstanding high-speed capabilities, fabrication with CMOS compatible processes and high reliability. The mainstream configurations are two-fold: ring resonator modulators (RRM) and Mach-Zehnder interferometer modulators (MZM). RRM...

We demonstrate an 8 by 14 Gbps compatible WDM link based on a single-section semiconductor mode-locked laser, silicon photonics resonant ring modulators and joint channel reamplification with a semiconductor optical amplifier operated in the linear regime. Individual channels reach a data rate of 25 Gbps with signal quality-factors above 7.

We report on the design of Silicon Mach-Zehnder carrier depletion modulators relying on epitaxially grown vertical junction diodes. Unprecedented spatial control over doping profiles resulting from combining local ion implantation with epitaxial overgrowth enables highly linear phase shifters with high modulation efficiency and comparatively low in...

High-speed silicon modulators based on the plasma effect in reverse-biased p(i)n junction phase shifters have been extensively investigated. The main challenge for such modulators is to maximize their modulation efficiency without compromising high-speed performance and insertion losses. Here, we propose a highly efficient silicon modulator based o...

We demonstrate a wavelength domain-multiplexed (WDM) optical link relying on a single section semiconductor mode-locked laser (SS-MLL) with quantum dash (Q-Dash) gain material to generate 25 optical carriers spaced by 60.8 GHz, as well as silicon photonics (SiP) resonant ring modulators (RRMs) to modulate individual optical channels. The link requi...

We demonstrate wavelength domain multiplexed (WDM) data transmission with a data rate of 14 Gbps based on optical carrier generation with a single-section semiconductor mode-locked laser (SS-MLL) and modulation with a Silicon Photonics (SiP) resonant ring modulator (RRM). 18 channels are sequentially measured, whereas the best recorded eye diagrams...

We present a multilayer 4 × 4 Butler matrix based on corrugated slot-coupled structures, which operates over the complete UWB band (3.1 to 10.6 GHz) with excellent phase and amplitude performance. A prototype has been fabricated which covers the UWB band with a measured return loss better than 21 dB, an isolation better than 24 dB, an amplitude imb...

In this paper, a novel frequency-locked loop (FLL) architecture for phase-noise reduction of wideband voltage-controlled oscillators (VCO) is presented. The circuit makes use of a phase-shifterless frequency discriminator, which completely avoids the use of any control circuitry to keep the loop in its quadrature condition, highly simplifying the l...

A six-port-based frequency discriminator for phase noise measurement is proposed. This circuit makes use of a delay line discriminator configuration, thus not requiring reference oscillator. Furthermore, the use of a six-port network allows an extremely simple and completely passive solution well suited for low power oscillator measurement. A detai...

In this work we propose the utilization of the Butler matrix as a six-port I/Q demodulator. The inherent symmetry of its topology allows to overcome the intrinsic amplitude and phase imbalances of the traditional approaches making it more suitable for the design of high performance six-port networks. To demonstrate the validity of the proposal a Bu...

A frequency locked loop (FLL) for phase noise reduction of wideband voltage controlled oscillators is proposed. The key building block of the system is a low noise (-160 dBV/Hz) and high sensitivity (22 V/GHz) delay line frequency discriminator with 5-8 GHz coverage, which makes use of a high performance multilayer hybrid. The authors derive closed...

Some achievements on multiport direct conversion receivers at microwave and optical frequencies are reported. Several sixport junctions with full UWB band (3.1-10.6 GHz) coverage will be presented and compared which, due to their low imbalances, allow to develop a six-port direct conversion receiver with analog I/Q recovery for the complete UWB ban...

In this paper a novel varactor-tuned frequency discriminator that makes use of two tunable dual-mode microstrip resonators is demonstrated which doubles the discriminator tuning bandwidth. To prove its validity a prototype of the tunable dual-mode microstrip resonator is manufactured and the measured results are used to study the frequency discrimi...

In this paper a robust technique for the design of high performance directional couplers is proposed. It combines the advantages of wiggly coupled lines and slot-coupled lines but overcomes their main limitations. The key to this novel technique is a new corrugated slot that allows perfect compensation of the even and odd mode phase velocities and...

A wide bandwidth and very well balanced six-port junction is reported. It makes use of recent theoretical results which show that six-port networks are extremely tolerant to common phase errors of some of its building blocks. This property can be advantageously used to implement an improved six-port juction made up of four hybrids and a 90° phase s...

In this work some of the latest advances in multi-port technology in microwave and optical frequencies are reviewed. At microwaves frequencies, multilayer technologies are clearly improving the capabilities of six-port networks designs to cover wider frequency bands with minimum imbalances. This is making feasible new applications such as ultra-wid...

A coherent receiver based on a 120° downconverter architecture, inherited from previous approaches at the microwave and optical fields, is proposed, analyzed, numerically evaluated and compared to the conventional 90° downconverter alternative. It is shown that, due to its superior calibration procedure, the new downconverter architecture allows fu...

In this work a high performance six-port junction is presented, which operates over the complete UWB 3.1 to 10.6 GHz band. A prototype has been fabricated which exhibits a return loss better than 21 dB, isolation better than 30 dB and centres with an amplitude imbalance of less than ±0.75 dB and a phase imbalance of less than ±5° across the whole U...

Since its introduction in 1994 direct conversion six-port receivers have attracted a considerable attention at microwave frequencies, with most recent work focusing on the so called six-port receivers with analog I/Q generation. Besides its applications at microwave frequencies, six-port receivers with I/Q regeneration play a crucial role in the op...

This paper presents a six-section multi-layer asymmetric 10 dB directional coupler based on offset broadside coupled striplines, using Low Temperature Co-fired Ceramic (LTCC) technology, which operates over a decade bandwidth from 1.8 to 18 GHz. It features high performance transitions between the external signal layer and the buried signal layers,...

We present a three-section quadrature hybrid based on slot-coupled directional couplers, which operates over a bandwidth from 3.1 to 10.6 GHz. A prototype has been fabricated which exhibits a return loss better than 20 dB, isolation around 20 dB, an amplitude imbalance between output ports of less than plusmn0.75 dB and a phase imbalance between +1...