We report on the development of a two-channel digital coherent optics (DCO) module, based on a monolithic InP photonic integrated circuit (PIC) transceiver and SiGe application-specific integrated circuit (ASIC), paired with a real-time 7 nm digital signal processing (DSP) ASIC. The high-performance coherent optical engine, which utilizes digital Nyquist subcarriers and probabilistic constellation shaping (PCS) techniques, enables long-haul and ultra-long-haul transmission distances over mixed fiber and amplifier types. This work discusses the performance of a DCO unit operating at multiple data rates over three practical real-world-like network distances. 800 Gb/s data transmission over a 1,000 km standard single mode fiber link was achieved using a 96 GBd, PCS-64QAM modulation format. Results of extended reaches of over 2,400 km and 5,000 km are also presented with data rates of 600 Gb/s and 400 Gb/s, respectively.

1.6 Tb/s optical engine is enabled through vertical integration of a 2-channel monolithic InP PIC with SiGe electronics and a real-time DSP ASIC operating at 100 Gbaud for 800 Gb/s transmission.

Plasmonic internal photoemission detectors (PIPED) have recently been shown to combine compact footprint and high bandwidth with monolithic co-integration into silicon photonic circuits, thereby opening an attractive route towards optoelectronic generation and detection of waveforms in the sub-THz and THz frequency range, so-called T-waves. In this paper, we further expand the PIPED concept by introducing a metal-oxide-semiconductor (MOS) interface with an additional gate electrode that allows to control the carrier dynamics in the device and the degree of internal photoemission at the metal-semiconductor interfaces. We experimentally study the behavior of dedicated field-effect (FE-)PIPED test structures and develop a physical understanding of the underlying principles. We find that the THz down-conversion efficiency of FE-PIPED can be significantly increased when applying a gate potential. Building upon the improved understanding of the device physics, we further perform simulations and show that the gate field increases the carrier density in the conductive channel below the gate oxide to the extent that the device dynamics are determined by ultra-fast dielectric relaxation rather than by the carrier transit time. In this regime, the bandwidth can be increased to more than 1 THz. We believe that our experiments open a new path towards understanding the principles of internal photoemission in plasmonic structures, leading to PIPED-based optoelectronic signal processing systems with unprecedented bandwidth and efficiency.

We report on the development of a $2\times 800$ Gbps/wave coherent module based on a monolithic InP transceiver PIC and real-time 7nm DSP ASIC capable of 800Gbps data transmission over record 1000km SMF-28 link using a 96Gbaud, PCS-64QAM modulation format.

We present our recent progress in coherent transmitters (Tx) and receivers (Rx) based on Photonic Integrated Circuits (PIC) on the InP platform. We demonstrate signal generation and transmission at 800 Gbit/s per optical channel.

We present a 1.6Tbps coherent transceiver delivering 800Gbps/wave transmission using integrated Tx/Rx functions with 50GHz bandwidth and 50kHz linewidth tunable lasers on a single 2-channel InP PIC, paired with a SiGe Driver and TIA ASIC.

Vertical optimization of DSP algorithms, analog electronics, optical components and PCB design is critical to maximize the SNR limit of the digital coherent MODEM. We demonstrate a record net ISD of 10.82b/s/Hz for a vertically optimized 256QAM transceiver operating at a symbol rate >50GBd.

Three-dimensional (3D) nano-printing of freeform optical waveguides, also referred to as photonic wire bonding, allows for efficient coupling between photonic chips and can greatly simplify optical system assembly. As a key advantage, the shape and the trajectory of photonic wire bonds can be adapted to the mode-field profiles and the positions of the chips, thereby offering an attractive alternative to conventional optical assembly techniques that rely on technically complex and costly high-precision alignment. However, while the fundamental advantages of the photonic wire bonding concept have been shown in proof-of-concept experiments, it has so far been unclear whether the technique can also be leveraged for practically relevant use cases with stringent reproducibility and reliability requirements. In this paper, we demonstrate optical communication engines that rely on photonic wire bonding for connecting arrays of silicon photonic modulators to InP lasers and single-mode fibres. In a first experiment, we show an eight-channel transmitter offering an aggregate line rate of 448 Gbit/s by low-complexity intensity modulation. A second experiment is dedicated to a four-channel coherent transmitter, operating at a net data rate of 732.7 Gbit/s - a record for coherent silicon photonic transmitters with co-packaged lasers. Using dedicated test chips, we further demonstrate automated mass production of photonic wire bonds with insertion losses of (0.7 ± 0.15) dB, and we show their resilience in environmental-stability tests and at high optical power. These results might form the basis for simplified assembly of advanced photonic multi-chip systems that combine the distinct advantages of different integration platforms.

Over the past years, interest in wireless THz communications with so-called T-waves has tremendously increased [1]-[4], because the large carrier frequencies in the range 0.2 THz to 0.9 THz support wide signal band-widths and consequently large data rates. Transmission over hundreds of meters and line rates exceeding 100 Gbit/s were demonstrated [5]-[10]. Typical atmospheric losses are 0.2 dB/100 m at 0.2 THz, 0.5 dB/100 m at 0.3 THz, 1.5 dB/100 m at 0.4 THz, and 5 dB/100 m at 0.9 THz. For transmission over a 100 m-distance, however, the unity-gain free-space propagation loss a L=100m dB = 10lg(4πL/λ) 2 = 120dB (λ = 1mm, f = 0.3THz) dominates. To combat this propagation loss, multiple directional antennas with a high gain per sector can be employed at the base station to boost the reach and the data throughput on transmission and reception.

The information rate (IR) of a digital coherent transceiver is constrained by the inherent practical signal-tonoise ratio (SNR) limit. Coded modulation, which is the combination of multi-level modulation and forward error correction, aims to maximize the IR within this SNR envelope. While probabilistic constellation shaping has enhanced this methodology by providing an increase in IR over conventionally employed square quadrature amplitude modulation (QAM) formats, it is the ability to eloquently tune the per wavelength IR by varying the symbol probabilities that has gained this scheme significant traction within optical communications in recent years. As commercial line cards continue their evolution towards 100 GBd and to modulation formats beyond 64QAM, we discuss the merits of probabilistic shaping for high symbol rate digital coherent transceivers in the presence of a practical SNR limit.

Chip-scale frequency comb generators have the potential to become key building blocks of compact wavelength-division multiplexing (WDM) transceivers in future metropolitan or campus-area networks. Among the various comb generator concepts, quantum-dash (QD) mode-locked laser diodes (MLLD) stand out as a particularly promising option, combining small footprint with simple operation by a DC current and offering flat broadband comb spectra. However, the data transmission performance achieved with QD-MLLD was so far limited by strong phase noise of the individual comb tones, restricting experiments to rather simple modulation formats such as quadrature phase shift keying (QPSK) or requiring hardware-based compensation schemes. Here we demonstrate that these limitations can be overcome by digital symbol-wise blind phase search (BPS) techniques, avoiding any hardware-based phase-noise compensation. We demonstrate 16QAM dual-polarization WDM transmission on 38 channels at an aggregate net data rate of 10.68 Tbit/s over 75 km of standard single-mode fiber. To the best of our knowledge, this corresponds to the highest data rate achieved through a DC-driven chip-scale comb generator without any hardware-based phase-noise reduction schemes.

We show 100 GBd 32QAM transmission enabled by hybrid integration of InP PICs featuring 40 kHz linewidth widely tunable lasers and SiGe electronics. A mean Q-factor of 6.2 dB after 500 km transmission is measured, demonstrating the feasibility of 800 Gbit/s waves for extended-reach applications.

Quantum-dash (QD) mode-locked laser diodes (MLLD) lend themselves as chip-scale frequency comb generators for highly scalable wavelength-division multiplexing (WDM) links in future data-center, campus-area, or metropolitan networks. Driven by a simple DC current, the devices generate flat broadband frequency combs, containing tens of equidistant optical tones with line spacings of tens of GHz. Here we show that QD-MLLDs can not only be used as multi-wavelength light sources at a WDM transmitter, but also as multi-wavelength local oscillators (LO) for parallel coherent reception. In our experiments, we demonstrate transmission of an aggregate net data rate of 3.9 Tbit/s (23 × 45 GBd PDM-QPSK, 7% FEC overhead) over 75 km standard single-mode fiber (SSMF). To the best of our knowledge, this represents the first demonstration of a coherent WDM link that relies on QD-MLLD both at the transmitter and the receiver.

Photonics might play a key role in future wireless communication systems that operate at THz carrier frequencies. A prime example is the generation of THz data streams by mixing optical signals in high-speed photodetectors. Over the previous years, this concept has enabled a series of wireless transmission experiments at record-high data rates. Reception of THz signals in these experiments, however, still relied on electronic circuits. In this paper, we show that wireless THz receivers can also greatly benefit from optoelectronic signal processing techniques, in particular when carrier frequencies beyond 0.1 THz and wideband tunability over more than an octave is required. Our approach relies on a high-speed photoconductor and a photonic local oscillator for optoelectronic down-conversion of THz data signals to an intermediate frequency band that is easily accessible by conventional microelectronics. By tuning the frequency of the photonic local oscillator, we can cover a wide range of carrier frequencies between 0.03 THz and 0.34 THz. We demonstrate line rates of up to 10 Gbit/s on a single channel and up to 30 Gbit/s on multiple channels over a distance of 58 m. To the best of our knowledge, our experiments represent the first demonstration of a THz transmission link that exploits optoelectronic signal processing techniques both at the transmitter and the receiver.

Get PDF Email Share Share with Facebook Tweet This Post on reddit Share with LinkedIn Add to CiteULike Add to Mendeley Add to BibSonomy Get Citation Copy Citation Text R. Going, S. Wolf, R. Maher, P. Studenkov, V. Lal, H. Tsai, S. Corzine, J. Zhang, B. Behnia, C. Di Giovanni, T. Vallaitis, J. Yan, J. Osenbach, M. Kuntz, T. Frost, H. Mousavi, S. Porto, S. Buggaveeti, H. Hodaei, Z. Wang, X. Xu, P. Evans, J. Rahn, T. Butrie, M. Ziari, D. Welch, and F. Kish, "InP-based Coherent PICs for 100 Gbaud Operation," in OSA Advanced Photonics Congress (AP) 2019 (IPR, Networks, NOMA, SPPCom, PVLED), OSA Technical Digest (Optica Publishing Group, 2019), paper SpM4E.3. Export Citation BibTex Endnote (RIS) HTML Plain Text Citation alert Save article

We propose a low-complexity digital implementation of the Kramers-Kronig receiver and analyze its performance and complexity. In simulations and experiments, we find that a relatively small number of filter taps is sufficient to achieve a reasonably high accuracy for the phase retrieval and for the reconstruction of the complex field. We show that the Kramers-Kronig receiver performance strongly depends on details of the system design. Unnecessarily broad optical filters decrease the reception quality, because additional noise makes the violation of the minimum-phase condition more likely. Narrow optical filters, however, impose high local oscillator laser stability and reduce the flexibility of this kind of receiver architecture. Further, we demonstrate Kramers-Kronig reception of 16 QAM signals at a net data rate of 267 Gbit/s after transmission over 300 km of standard single-mode fiber. We compare the performance with a conventional intradyne receiver. In a back-to-back setting, we increase the net data rate to 300 Gbit/s.

Hybrid photonic integration allows to combine the complementary advantages of different material platforms while maintaining the processing and scalability advantages of monolithically integrated systems. Here we give an overview on our research in the field of hybrid integration, combining multi-chip approaches on a package level with hybrid on-chip integration using both back-end-of-line (BEOL) and front-end-of-line (FEOL) processes.

In selective laser melting processes, the precise synchronization of mirror motion and laser illumination is one of the major influential factors, determining the quality of additively manufactured metal parts. Utilizing a novel laser beam diagnostic approach, we are able to determine timing errors on the scale of a few its. Since the method does not involve the structuring of test specimens with certain processing windows, the analysis is applicable over a wide range of power levels, allowing the direct observation of power dependent laser switching delays, and their influence on the aspired shape accuracy. We present investigations of power dependent start/stop-point displacement over a variation of 400 W and devised a quick and convenient calibration procedure.