Dedicated multi-project wafer (MPW) runs for photonic integrated circuits (PICs) from Si foundries mean that researchers and small-to-medium enterprises (SMEs) can now afford to design and fabricate Si photonic chips. While these bare Si-PICs are adequate for testing new device and circuit designs on a probe-station, they cannot be developed into prototype devices, or tested outside of the laboratory, without first packaging them into a durable module. Photonic packaging of PICs is significantly more challenging, and currently orders of magnitude more expensive, than electronic packaging, because it calls for robust micron-level alignment of optical components, precise real-time temperature control, and often a high degree of vertical and horizontal electrical integration. Photonic packaging is perhaps the most significant bottleneck in the development of commercially relevant integrated photonic devices. This article describes how the key optical, electrical, and thermal requirements of Si-PIC packaging can be met, and what further progress is needed before industrial scale-up can be achieved.

Fluorescence spectroscopy has been extensively investigated for disease diagnosis. In this framework, optical tissue phantoms are widely used for validating the biomedical device system in a laboratory environment outside of clinical procedures. Moreover, it is fundamental to consider that there are several scattering components and chromophores inside biological tissues and the interplay between scattering and absorption may result in a distortion of the emitted fluorescent signal. In this work, the photophysical behaviour of a set of liquid, tissue-like phantoms containing different compositions was analysed: phosphate buffer saline (PBS) was used as the background medium, low fat milk as a scatterer, Indian ink as an absorber and protoporphyrin IX (PpIX) dissolved in dimethyl formamide (DMF) as a fluorophore. We examined the collected data in terms of the impact of surfactant Tween-20 on the background medium, scattering effects and combination of scattering and absorption within a luminescent body on PpIX. The results indicated that the intrinsic emission peaks are red shifted by the scattering particles or surfactant, whilst the scattering agent and the absorbent can alter the emission intensity substantially. We corroborated that phantoms containing higher surfactant content (>0.5% Tween 20) are essential to prepare stable aqueous phantoms.

A directly modulated laser diode module with over 10 Gb/s transmission and its performance, packaging process, and manufacturability are presented. The butterfly package consists of a V-connector, heat sink, and L-shaped microstrip line (MSL) which includes an integrated impedance matching resistor. The optical system consists of a 1.3- distributed feedback laser and a micro lens with isolator. A large modulation bandwidth of up to 15 GHz was obtained, and the eye diagram for 10 Gb/s modulation was clearly visible. Importantly, using an L-shaped MSL with integrated impedance matching resistor design, the module design is significantly simplified and can provide flexibility to insert various optical coupling systems. Moreover, since the laser was mounted directly on Kovar heat sink, optical output power reduction by thermal effects was 1 dB up to 50°C without active cooling. As a result of the simplified module configuration with flexibility, the module packaging process may be highly efficient for mass production.

In this paper, the influence of packaging-induced RF signal degradation on an optoelectronic modulator module is investigated. A directly modulated laser (DML) is modeled and packaged in a butterfly-type package. A distributed 3-D electromagnetic model is built based on this laser module. In the packaging assembly procedure, impedance mismatching and ground discontinuity on microwave transmission will cause unwanted signal decays and resonances. We specify the RF degradation in three regions: 1) the RF connector, 2) the RF substrate, and 3) the mode transition region between the optoelectronic subsystem and the package. The RF transmission characteristics in these regions are extracted and analyzed in detail. The results indicate that by optimizing the packaging design, strong resonances and signal decays can be eliminated or compensated over a wide frequency range. The measured scattering parameters show that the proposed packaging assembly has a resonance-free bandwidth of 31.2 GHz, and the DML module exhibits a wide 3 dB bandwidth of 15.1 GHz.