Francisco Soares

An introduction to InP-based generic integration technology

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.

Optically beamformed beam-switched adaptive antennas for fixed and mobile broad-band wireless access networks

In this paper, a 3-bit optical beamforming architecture based in 2/spl times/2 optical switches and dispersive media is proposed and demonstrated. The performance of this photonic beamformer is experimentally demonstrated at 42.7 GHz in both transmission and reception modes. The progress achieved for realizing these architectures with integrated optics is also reported. Due to its advanced features (i.e., potential fast-switching, huge bandwidth, and immunity to electromagnetic interference), the architecture is a very promising alternative to traditional beamforming technologies for implementing beamformed base-station antennas in fixed and mobile broad-band wireless access networks operating in the millimeter-wave band. The study presented here has been carried out in the frame of the IST 2000-25390 OBANET project.

Validation of the Building-Block-Based Approach for the Design of Photonic Integrated Circuits

The concept of building block and circuit-model simulation in photonics is presented and discussed, pointing out their key role in a generic foundry approach. Circuit simulation based on building-block approach, in addition and alternative to the classical electromagnetic analysis, emerges as the most useful framework for a deep exploitation of the potentiality of photonics for the large-scale integration of complex circuits. The reliability of building-block-based design and simulation of photonics integrated circuits is discussed and comparisons between simulated and measured behavior of three challenging test circuits are used as proof of concept of the validity of this approach.

Hybrid InP-polymer 30 nm tunable DBR laser for 10 Gbit/s direct modulation in the C-Band

A C-Band hybrid InP-polymer tunable DBR laser for direct modulation is presented. The DBR tunes 34 nm with output powers larger 8 mW and SMSRs above 40 dB. 10 Gbit/s operation shows open eye diagrams.

Semi-insulating substrate based generic InP photonic integration platform

In the European projects EuroPIC and PARADIGM development of an InP based generic photonic integration technology is being undertaken to implement complex InP based application-specific photonic integrated circuits (ASPIC) with transmit and receive functionalities from a set of basic building blocks. The integration platform pursued at Fraunhofer HHI is building on semi-insulating substrate. Recently a variety of receiver-type PIC with up to 40 GHz bandwidth capability designed by external users was fabricated in multi-project wafer runs. Examples are demonstrated. Extension of this platform to include transmit functionalities is underway using an MOVPE based butt-coupling approach.

Progress in polymer-based components for next-generation PON applications

Polymer components for next-generation WDM PON are presented, incl. 8ch OLT-Tx and OLT-Rx devices using polymer AWGs and InP-based DFB laser and photo diode arrays together with a 40nm wide tunable InP/polymer Bragg grating laser for realizing colorless ONUs.

A Compact and Fast Photonic True-Time-Delay Beamformer with Integrated Spot-Size Converters

Spot-size converters, based on a vertical taper, have been successfully integrated with electro-optic MZI switches. A chip containing a matrix of switches has been fabricated. The fiber-chip coupling loss via the SSCs is 3.5 dB.

Photonic true-time delay beamformer for broadband wireless access networks at 40 GHz band

The design parameters, sensitivity analysis and time delay measurements of a photonic true-time delay beamformer for broadband adaptive wireless access networks in the 40 GHz band are presented. The beamforming is achieved by using a multiwavelength laser in combination with a digital delay line based on optical switches and dispersive fibers.

Photonic Integrated Circuits on InP

This chapter is devoted to photonic integrated circuits (PIC) on InP semiconductor basis. This materials platform is capable of monolithically integrating not only passive optical waveguide and receiver (Rx) devices but also transmitter (Tx) type structures, in particular optical amplifiers and lasers. In the first part the principal integration approaches of these diverse device structures will be addressed: vertical integration schemes relying on evanescent optical coupling between vertically stacked device levels; and lateral integration schemes exploiting in-plane optical coupling of the optical devices. In the latter case, butt-joint coupling, selective-area-growth, and quantum-well intermixing are being used, all of them geared to accomplish lateral band gap engineering. In the following section, recent examples of PICs based on proprietary technology solutions will be given. The second part of this chapter discusses generic photonic integration copying the foundry model successfully established in the electronics world. In this model, using defined building blocks, PIC design and manufacturing are strictly separated, thereby facilitating open access to this technology. As an example of such a generic platform, the TxRx technology developed by Fraunhofer HHI will be outlined. Selected building blocks will be described, and representative PICs made on multi-project wafer runs will be shown highlighting the viability of the foundry approach. In addition, the supply chain required for successful adoption of the foundry model will be briefly covered, including the design software environment, testing and wafer validation capabilities, and also generic packaging.

38-GHz millimeter wave beam steered fiber wireless systems for 5G indoor coverage: architectures, devices, and links

Millimeter wave (mm-wave) beam steering is a key technique for the next generation (5G) wireless communication. The 28 and 38-GHz bands are widely considered as the candidates for 5G. In the context of indoor coverage, fiber-wireless systems with multiple simplified remote antenna sites are attractive to avoid the indoor coverage problem caused by the high wall penetration loss of mm-wave signals. To allow enough antenna gain at the mm-wave bands, radio beam steering (and beamforming) is desired. Combining fiber-wireless system with remotely controlled photonic mm-wave beam steering can bring significant advances in terms of energy efficiency and cost. In this paper, we explore two kinds of indoor fiber-wireless network architectures for such mm-wave beam steering. Then, we discuss and investigate the key enabling device, which is an arrayed waveguide grating feedback loop (AWG-loop). Based on the AWG-loop, we further design two fiber-wireless links to accommodate the two network architectures. Both links with bit rates from 50 Mb/s to 8 Gb/s per spatial channel are experimentally demonstrated with a 38-GHz carrier frequency. The advanced reversely modulated optical transmitter and half-cycled 16 quadrature amplitude modulation (QAM-16) are employed to realize a simplified mm-wave beam steered fiber-wireless link with the record-breaking 16-b/s/Hz (4 spatial channels