Photonic integrated circuits (PICs) are considered as the way to make photonic systems or subsystems cheap and ubiquitous. PICs still are several orders of magnitude more expensive than their microelectronic counterparts, which has restricted their application to a few niche markets. Recently, a novel approach in photonic integration is emerging which will reduce the R&D and prototyping costs and the throughput time of PICs by more than an order of magnitude. It will bring the application of PICs that integrate complex and advanced photonic functionality on a single chip within reach for a large number of small and larger companies and initiate a breakthrough in the application of Photonic ICs. The paper explains the concept of generic photonic integration technology using the technology developed by the COBRA research institute of TU Eindhoven as an example, and it describes the current status and prospects of generic InP-based integration technology.

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An introduction to InP-based generic integration technology

Modern data centers increasingly rely on interconnects for delivering critical communications connectivity among numerous servers, memory, and computation resources. Data center interconnects turned to optical communications almost a decade ago, and the recent acceleration in data center requirements is expected to further drive photonic interconnect technologies deeper into the systems architecture. This review paper analyzes optical technologies that will enable next-generation data center optical interconnects. Recent progress addressing the challenges of terabit/s links and networks at the laser, modulator, photodiode, and switch levels is reported and summarized.

Recent advances in optical technologies for data centers: a review

Graphene is an ideal material for optoelectronic applications. Its photonic properties give several advantages and complementarities over Si photonics. For example, graphene enables both electro-absorption and electro-refraction modulation with an electro-optical index change exceeding 10$^{-3}$. It can be used for optical add-drop multiplexing with voltage control, eliminating the current dissipation used for the thermal detuning of microresonators, and for thermoelectric-based ultrafast optical detectors that generate a voltage without transimpedance amplifiers. Here, we present our vision for grapheme-based integrated photonics. We review graphene-based transceivers and compare them with existing technologies. Strategies for improving power consumption, manufacturability and wafer-scale integration are addressed. We outline a roadmap of the technological requirements to meet the demands of the datacom and telecom markets. We show that graphene based integrated photonics could enable ultrahigh spatial bandwidth density , low power consumption for board connectivity and connectivity between data centres, access networks and metropolitan, core, regional and long-haul optical communications.

Graphene-Based Integrated Photonics For Next-Generation Datacom And Telecom

Graphene is an ideal material for optoelectronic applications. Its photonic properties give several advantages and complementarities over Si photonics. For example, graphene enables both electro-absorption and electro-refraction modulation with an electro-optical index change exceeding 10−3. It can be used for optical add–drop multiplexing with voltage control, eliminating the current dissipation used for the thermal detuning of microresonators, and for thermoelectric-based ultrafast optical detectors that generate a voltage without transimpedance amplifiers. Here, we present our vision for graphene-based integrated photonics. We review graphene-based transceivers and compare them with existing technologies. Strategies for improving power consumption, manufacturability and wafer-scale integration are addressed. We outline a roadmap of the technological requirements to meet the demands of the datacom and telecom markets. We show that graphene-based integrated photonics could enable ultrahigh spatial bandwidth density, low power consumption for board connectivity and connectivity between data centres, access networks and metropolitan, core, regional and long-haul optical communications.

Graphene-based integrated photonics for next-generation datacom and telecom

Photonic switches are increasingly considered for insertion in high performance datacenter architectures to meet the growing performance demands of interconnection networks. We provide an overview of photonic switching technologies and develop an evaluation methodology for assessing their potential impact on datacenter performance. We begin with a review of three categories of optical switches, namely, free-space switches, III-V integrated switches and silicon integrated switches. The state-of-the-art of MEMS, LCOS, SOA, MZI and MRR switching technologies are covered, together with insights on their performance limitations and scalability considerations. The performance metrics that are required for optical switches to truly emerge in datacenters are discussed and summarized, with special focus on the switching time, cost, power consumption, scalability and optical power penalty. Furthermore, the Pareto front of the switch metric space is analyzed. Finally, we propose a hybrid integrated switch fabric design using the III-V/Si wafer bonding technique and investigate its potential impact on realizing reduced cost and power penalty.

Photonic switching in high performance datacenters [Invited]

We present what is to our knowledge the first active-passive monolithically integrated 16×16 switch. The active InP/InGaAsP elements provide semiconductor optical amplifier gates in a multistage rearrangeably nonblocking switch design. Thirty-two representative connections, including the shortest, longest, and comprehensive range of intermediate paths have been assessed across the switch circuit. The 10  Gb/s signal routing is demonstrated with an optical signal-to-noise ratio up to 28.3  dB/0.1  nm and a signal extinction ratio exceeding 50 dB.

Monolithic active-passive 16 × 16 optoelectronic switch.

We propose, characterise and demonstrate a photonic multistage switching circuit operating at 160 Gb/s serial line rates. The circuit is realised on a re-grown active-passive wafer exploiting multiple stages of loss-compensating semiconductor optical amplifier crossbar switch elements. Excellent 40 dB crosstalk extinction is achieved, with signal to noise ratios of up to 39 dB/0.06 nm. Low loss circuit operation is presented, with the prospect of gain if antireflection coatings are applied at the input and output facet.

Monolithic Multistage Optoelectronic Switch Circuit Routing 160 Gb/s Line-Rate Data

A highly compact quantum dot semiconductor optical amplifier based crossbar switch is proposed, fabricated and demonstrated at a wavelength of 1550 nm. Power penalty measurements at 10 Gbit/s show minimal path dependence with values of 0.15 to 0.25 dB and an extinction ratio of 24 dB.

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Integrated 2 X 2 quantum dot optical crossbar switch in 1.55 μm wavelength range

A monolithic 4×4 WDM cross-connect is presented comprising a broadcast select switch and four wavelength selective switches. Multi-path routing is demonstrated for both co-and counter-propagating data with under 1dB power penalty indicating negligible crosstalk.

Multi-path routing in an monolithically integrated 4×4 broadcast and select WDM cross-connect

A remotely reconfigurable wavelength selective switch is proposed which implements label detection and signal gating in the same SOA array. A proof of principle monolithic circuit is presented showing dynamic nanosecond label-controlled switching.

A. Albores-Mejia

Papers

Monolithic active-passive 16 × 16 optoelectronic switch.

Monolithic Multistage Optoelectronic Switch Circuit Routing 160 Gb/s Line-Rate Data

Integrated 2 X 2 quantum dot optical crossbar switch in 1.55 μm wavelength range

Multi-path routing in an monolithically integrated 4×4 broadcast and select WDM cross-connect

Fast remotely reconfigurable wavelength selective switch