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We demonstrate a 3 × 25 Gbit/s SFP transceiver assembly using 3D-printed optical coupling elements to connect multimode multi-core fibers to linear VCSEL and photodiode arrays. Passive alignment yields average coupling losses below 0.7 dB, ensuring conformity with the IEEE 802.3 power budget.

Key advances which enabled the InP photonic integrated circuit (PIC) and the subsequent progression of InP PICs to fully integrated multichannel DWDM system-on-chip (SOC) PICs are described. Furthermore, the current state-of-the-art commercial multichannel SOC PICs are reviewed as well as key trends and technologies for the future of InP-based PICs in optical communications.

We demonstrate a fully integrated multi-channel InP-based coherent transmitter photonic integrated circuits (PICs) with extended C-band tunability, operating at 33 and 44 Gbaud per channel under 16-QAM dual-polarization modulation. PICs are demonstrated integrating up to 14-channels enabling multi-Tb/s total PIC capacities.

Complex photonic-integrated circuits (PIC) may have strongly non-planar topologies that require waveguide crossings (WGX) when realized in single-layer integration platforms. The number of WGX increases rapidly with the complexity of the circuit, in particular when it comes to highly interconnected optical switch topologies. Here, we present a concept for WGX-free PIC that relies on 3D-printed freeform waveguide overpasses (WOP). We experimentally demonstrate the viability of our approach using the example of a 4 × 4 switch-and-select (SAS) circuit realized on the silicon photonic platform. We further present a comprehensive graph-theoretical analysis of different n × n SAS circuit topologies. We find that for increasing port counts n of the SAS circuit, the number of WGX increases with n4, whereas the number of WOP increases only in proportion to n2.

Fully integrated monolithic, multi-channel InP-based coherent receiver PICs and transceiver modules with extended C-band tunability are described. These PICs operate at 33 and 44 Gbaud per channel under dual polarization (DP) 16-QAM modulation. Fourteen-channel monolithic InP receiver PICs show integration and data rate scaling capability to operate at 44 Gbaud under DP 16-QAM modulation for combined 4.9 Tb/s total capacity. Six channel simultaneous operation of a commercial transceiver module at 33 Gbaud is demonstrated for a variety of modulation formats including DP 16-QAM for >1.2Tbit/s aggregate data capacity.

A single wavelength 66 GBd DP-1024QAM transceiver with a coded bit rate of 1.32 Tb/s is demonstrated. Constellation shaping is employed to tailor the symbol distribution to achieve a net bit rate of 680 Gb/s and spectral efficiency of 9.35 b/s/Hz after 400 km transmission.

We report InP-based coherent transmitter PICs with hybrid integrated SiGe drivers operating at 100GBd, 32QAM back-to-back (1 Tb/wave capable), and at 100GBd, 16QAM over 1400km. Coherent Tx (Rx) PICs with hybrid integrated drivers (amplifiers) operate at 66GBd, 64QAM over 200km.

Nanophotonic modulators and photodetectors are key building blocks for high-speed optical interconnects in datacom and telecom networks. Besides power efficiency and high electro-optic bandwidth, ultra-compact footprint and scalable co-integration with electronic circuitry are indispensable for highly scalable communication systems. In this paper, we give an overview on our recent progress in exploring nanophotonic modulators and photodetectors that combine the specific strengths of silicon photonic and plasmonic device concepts with hybrid integration approaches. Our work comprises electro-optic modulators that exploit silicon-organic hybrid (SOH) and plasmonic-organic hybrid (POH) integration to enable unprecedented energy efficiency and transmission speed, as well as waveguide-based plasmonic internal photo-emission detectors (PIPED) with record-high sensitivities and bandwidths.

We generate record-high line rates of 400 Gbit/s (100 GBd 16QAM) using a silicon-based IQ modulator. With a BER=1.9×10"2 we transmit a net data rate of 333 Gbit/s, the highest value for a semiconductor-based modulator.

Driven by optical communications, a powerful toolbox for photonic integration has emerged over the last years. We review specific opportunities that can be unlocked by applying these technologies to the field of metrology and sensing.

100 Gbit/s three-level (50 Gbit/s 00K) signals are generated using a silicon-organic hybrid modulator and a BiCMOS duobinary driver IC at a BER of 8.5x10(-5)(

We report on the hybrid integration of silicon-on-insulator slot waveguides with organic electro-optic materials. We investigate and compare a polymer composite, a dendron-based material, and a binary-chromophore organic glass (BCOG). A record-high in-device electro-optic coefficient of 230 pm/V is found for the BCOG approach resulting in silicon-organic hybrid Mach-Zehnder modulators that feature low $U_{\pi }L$ -products of down to 0.52 Vmm and support data rates of up to 40 Gbit/s.

Organic materials combined with strongly guiding silicon waveguides open the route to highly efficient electro-optical devices. Modulators based on the so-called silicon-organic hybrid (SOH) platform have only recently shown frequency responses up to 100 GHz, high-speed operation beyond 112 Gbit/s with fJ/bit power consumption. In this paper, we review the SOH platform and discuss important devices such as Mach-Zehnder and IQ-modulators based on the linear electro-optic effect. We further show liquid-crystal phase-shifters with a voltage-length product as low as V pi L = 0.06 V.mm and sub-mu W power consumption as required for slow optical switching or tuning optical filters and devices.

Advanced wavelength-division multiplex-ing (WDM) requires both efficient multi-wavelength light sources to generate optical carriers and highly scalable photonic-electronic interfaces to encode data on these carriers. In this paper, we give an overview on our recent progress regarding silicon-organic hy-brid (SOH) integration and comb-based WDM transmission.

Low-cost photonic integrated circuits (PIC) become increasingly important in medical applications like optical coherence tomography (OCT) for eye care and endoscopy as well as in industrial metrology for distance scanning of surfaces and volumes. We report on two OCT systems fully integrated on a silicon-on- insulator (SOI) chip. With an on-chip reference path, we image objects in distances (5…10)mm from the chip edge with a depth resolution of 11µm and a dynamic range of 53dB . Employing an off-chip reference path, objects are imaged in distances (8000…8010)mm from the chip with a depth resolution of 30µm and a dynamic range of 60dB.

Limitations of silicon photonics can be overcome by hybrid integration of silicon photonic or plasmonic circuits with organic materials or by photonic multi-chip systems. We give an overview on our recent progress regarding both silicon-organic hybrid (SOH) integration and multi-chip integration enabled by photonic wire bonding.

With a silicon-based modulator we generate single-polarization 16QAM signals at symbol rates of 63 GBd (252 Gbit/s, 22 fJ/bit, BER = 4.1×10∼3). The experiments show a path towards Si-based 500 Gbit/s dual-polarization single-wavelength transmitters.

We demonstrate the generation of higher-order modulation formats using silicon-based inphase/quadrature (IQ) modulators at symbol rates of up to 100 GBd. Our devices exploit the advantages of silicon-organic hybrid (SOH) integration, which combines silicon-on-insulator waveguides with highly efficient organic electro-optic (EO) cladding materials to enable small drive voltages and sub-millimeter device lengths. In our experiments, we use an SOH IQ modulator with a {\pi}-voltage of 1.6 V to generate 100 GBd 16QAM signals. This is the first time that the 100 GBd mark is reached with an IQ modulator realized on a semiconductor substrate, leading to a single-polarization line rate of 400 Gbit/s. The peak-to-peak drive voltages amount to 1.5 Vpp, corresponding to an electrical energy dissipation in the modulator of only 25 fJ/bit.

[invited] We introduce ABC laminate metamaterials composed of layers of three different dielectrics. Each layer has zero bulk second-order optical nonlinearity, yet centro-symmetry is broken locally at each inner interface. To achieve appreciable effective bulk metamaterial second-order nonlinear optical susceptibilities, we densely pack many inner surfaces to a stack of atomically thin layers grown by conformal atomic-layer deposition. For the ABC stack, centro-symmetry is also broken macroscopically. Our experimental results for excitation at around 800 nm wavelength indicate interesting application perspectives for frequency conversion or electro-optic modulation in silicon photonics.

We demonstrate a silicon-organic hybrid (SOH) Mach-Zehnder modulator suitable for 100 Gbit/s on-off keying (OOK) with peak-to-peak drive voltages of 1.4 V and energy consumption below 100 fJ/bit. Devices were fabricated using standard processes on a commercial silicon photonic platform.

Silicon-organic hybrid (SOH) integration combines silicon photonic devices with electro-optic organic cladding materials. We demonstrate that SOH modulators can be used to generate advanced modulation formats with high symbol rates at low operating voltages and low energy consumption. Moreover, we show that the SOH approach can be extended to plasmonic waveguide structures, leading to the plasmonic-organic hybrid (POH) concept.

Silicon photonics offers tremendous potential for inexpensive high-yield photonic-electronic integration by enabling fabless fabrication and joint processing of photonic and electronic circuitry. Besides conventional dielectric waveguides, plasmonic structures can also be efficiently realized on the silicon photonic platform, thereby reducing the device footprint by more than an order of magnitude. Silicon and metals, however, fall short of certain optical properties that are indispensable for high-performance photonic devices. In particular, neither material exhibits an appreciable second-order optical nonlinearity, thereby making efficient electro-optic modulators challenging.

We demonstrate silicon-organic hybrid (SOH) modulators for generating advanced modulation formats at high data rates and with low energy consumption. SOH integration combines slot waveguides on conventional silicon-on-insulator substrates with highly efficient electro-optic materials. With this approach we generate 16QAM signals at symbol rates of 28 GBd and 40 GBd leading to gross data rates (net data rates) of up to 160 Gbit/s (133 Gbit/s) for a single polarization. This is the highest value achieved by a silicon-based modulator up to now. With a maximum symbol rate of 28 GBd, low drive voltages of only 0.6 Vpp are sufficient and result in a record-low energy consumption of only 19 fJ/bit. This is the lowest energy consumption that has so far been reported for a 16QAM modulator at 28 GBd.

Limitations of silicon photonics can be overcome by hybrid integration or by photonic multi-chip systems. We give an overview on recent progress regarding silicon-organic hybrid (SOH) integration as well as multi-chip integration enabled by photonic wire bonding.

We show 64 GBd 4ASK signaling with a silicon-organic hybrid Mach-Zehnder modulator, allowing data rates of up to 128 Gbit/s. The device is operated at room temperature and at 80 °C.

Chip-scale frequency comb sources are likely to become key elements of future terabit/s optical transceivers. We investigated and demonstrate the viability of different comb generation schemes for transmission at data rates beyond 1 Tbit/s.

High-speed interconnects in data-center and campus-area networks crucially rely on efficient and technically simple transmission techniques that use intensity modulation and direct detection (IM/DD) to bridge distances of up to a few kilometers. This requires electro-optic modulators that combine low operation voltages with large modulation bandwidth and that can be operated at high symbol rates using integrated drive circuits. Here we explore the potential of silicon-organic hybrid (SOH) Mach-Zehnder modulators (MZM) for generating high-speed IM/DD signals at line rates of up to 120 Gbit/s. Using a SiGe BiCMOS signal-conditioning chip, we demonstrate that intensity-modulated duobinary (IDB) signaling allows to efficiently use the electrical bandwidth, thereby enabling line rates of up to 100 Gbit/s at bit error ratios (BER) of 8.5 x 10(-5). This is the highest data rate achieved so far using a silicon-based MZM in combination with a dedicated signal-conditioning integrated circuit (IC). We further show four-level pulse-amplitude modulation (PAM4) at lines rates of up to 120 Gbit/s (BER = 3.2 x 10(-3)) using a high-speed arbitrary-waveform generator and a 0.5 mm long MZM. This is the highest data rate hitherto achieved with a sub-millimeter MZM on the silicon photonic platform. (C) 2017 Optical Society of America

We demonstrate 16QAM and QPSK modulation at symbol rates of 40 GBd and 45 GBd using a silicon-based IQ modulator. The device enables data rates up to 160 Gbit/s in a single polarization with an estimated energy consumption of 120fJ/bit.

We demonstrate generation and transmission of QPSK and 16QAM signals by directly interfacing highly efficient silicon-organic hybrid (SOH) modulators to GTH ports of an FPGA. Peak-to-peak voltages amount to only 0.41 V-pp. Neither digital-to-analog converters (DAC) nor drive amplifiers are required.

High-speed optical interconnects rely on advanced wavelength-division multiplexing (WDM) schemes. However, while photonic-electronic interfaces can be efficiently realized on silicon-on-insulator chips, dense integration of the corresponding light sources still represents a major challenge. Chip-scale frequency comb sources present an attractive alternative for providing a multitude of optical carriers for WDM transmission. In this paper, we give an overview on our recent progress towards terabit communications with chip-scale frequency comb sources. In a first set of experiments, we demonstrate frequency comb generation based on silicon-organic hybrid (SOH) electro-optic modulators, enabling transmission data rates of up to 1.152 Tbit/s. A second set of experiments demonstrates Kerr comb generation in nonlinear integrated microcavities, leading to data rates of up to 1.44 Tbit/s. Our experiments demonstrate that frequency comb generation in chip-scale devices represents a viable approach to terabit/s communications.

We demonstrate a synthetic-wavelength interferometry system on a silicon photonic chip, comprising an interferometer with tunable power splitting ratio and photodetectors. The system enables distance measurements with errors below 5 μm and acquisition times of 14 μs.

We demonstrate a waveguide-based frequency shifter on the silicon photonic platform, enabling frequency shifts up to 10 GHz. The device is realized by silicon-organic hybrid (SOH) integration. Temporal shaping of the drive signal allows the suppression of spurious side-modes by more than 23 dB.

We demonstrate a waveguide-based frequency shifter on the silicon-organic hybrid (SOH) platform, enabling frequency shifts up to 10 GHz. Spurious side-modes are suppressed by more than 23 dB using temporal shaping of the drive signal.

Silicon-organic hybrid (SOH) integration can extend the capabilities of silicon photonics by combining silicon-on-insulator (SOI) waveguides with functional organic cladding materials. This enables energy-efficient electro-optic modulators and ultra-compact phase shifters. We review recent progress in SOH integration, discussing both fundamental device concepts and experimental demonstrations.

A compact micro-optical interferometer is presented that combines two optical 90° hybrids or, alternatively, four delay interferometers into one interferometer structure sharing one tunable delay line. The interferometer can function as a frontend of either a coherent receiver or of a self-coherent receiver by adjusting the waveplates and the delay line. We built a prototype on a LIGA bench. We characterized the device and demonstrated its functionality by successful reception of a 112 Gbit/s signal.

Silicon modulators are maturing and it is anticipated that they are going to substitute state-of-the art modulators. We review current silicon modulator approaches and then discuss the silicon-organic hybrid (SOH) approach in more detail. The SOH approach has recently enabled the operation with an energy consumption of 60 fJ/bit and demonstrated the generation of up to 112 Gbit/s per polarization in a compact silicon modulator of 1.5 mm length.

The functionality of silicon photonics can be extended by combination with organic materials and by multi-chip integration. We give an overview of the underlying concepts of silicon-organic hybrid (SOH) integration and photonic wire bonding.

A compact polarization-diversity self-coherent receiver with reduced complexity is proposed. Requirements on input polarization tracking is relaxed by a variant CMA equalizer. Ex-periments are performed for 50 and 100 Gb/s PolMUX-NRZ-QPSK signals.

Structuring optical materials on a nanometer scale can lead to artificial effective media, or metamaterials, with strongly altered optical behavior. Metamaterials can provide a wide range of linear optical properties such as negative refractive index, hyperbolic dispersion, or magnetic behavior at optical frequencies. Nonlinear optical properties, however, have only been demonstrated for patterned metallic films which suffer from high optical losses. Here we show that second-order nonlinear metamaterials can also be obtained from non-metallic centrosymmetric constituents with inherently low optical absorption. In our proof-of-principle experiments, we have iterated atomic-layer deposition (ALD) of three different constituents, A = Al$_2$O$_3$, B = TiO$_2$ and C = HfO$_2$. The centrosymmetry of the resulting ABC stack is broken since the ABC and the inverted CBA sequences are not equivalent - a necessary condition for non-zero second-order nonlinearity. To the best of our knowledge, this is the first realization of a bulk nonlinear optical metamaterial., Comment: 3 figures, 11 pages; v2: corrected email

A dual-quadrature coherent receiver based on a polymer planar lightwave circuit (PLC) is presented. This receiver comprises two separate optical 90 degrees-hybrid chips made of polymer waveguides and hybridly integrated with InGaAs/InP photodiode (PD) arrays. The packaged receiver was successfully operated in 112 Gbit/s dual-polarization quadrature phase-shift keying (QPSK) transmission experiments. In back-to-back configuration the OSNR requirement for a BER value of 10(-3) was 15.1 dB which has to be compared to a theoretical limit of 13.8 dB.

Silicon-organic hybrid (SOH) and plasmonic-organic hybrid (POH) integration combines organic clectro-optic materials with silicon photonic and plasmonic waveguides, The concept enables fast and power-efficient modulators that support advanced modulation formats such as QPSK and 16QAM.

We demonstrate a silicon-based 16QAM modulator with a record-low drive voltage of 0.6Vpp and an energy consumption of 19fJ/bit. The device employs silicon slot waveguides with electro-optic organic cladding and enables data transmission at 112Gbit/s.