Co-packaging of optics and electronics for data center switches has been proposed to reduce system-level power consumption by minimizing power-hungry electrical interconnects. Co-packaging optical components near high-temperature electronics, however, can diminish their performance and reliability. Moreover, limitations of the switch environment, such as restricted footprint, power, and number of fiber attachments can limit practical co-packaging implementations. Here, we study four architectures for co-packaged optical interfaces using either single- or multi-wavelength light sources that can be either external to or integrated with the optical interfaces. We model the temperature- and current-dependent performance and reliability of the sources and calculate the link budget for switch bandwidths up to 102.4 Tb/s. We compare architectures based on coherent and direct detection and find that all coherent detection architectures support 102.4 Tb/s switching with over 13 dB link budget, while most direct detection architectures scale to 51.2 Tb/s or 102.4 Tb/s switching with link budgets less than 5 dB. In addition, we demonstrate that external-source architectures require wavelength-division multiplexing at lower switch bandwidths and consequently have link budgets 1-5 dB lower than integrated source architectures. Further, we demonstrate that higher-power lasers can scale external architectures to 102.4 Tb/s switching with over 4 dB link budgets. Finally, for 51.2 Tb/s switching, we show that a reduction in integrated source temperature improves link budgets by 2-4 dB and direct detection external-source architectures can achieve greater than 5 dB link budget with fewer than 300 fiber attachments.

External vs. Integrated Light Sources for Intra-Data Center Co-Packaged Optical Interfaces

Review of the technology of a single mode fiber coupling to a laser diode

Generalized Model and Configuration Design of Multiple-Axis Flexure Hinges

We have demonstrated an effective approach to fabricating ultrathin lensed photonic crystal fibers (PCFs) with long working distances. The analytic function of the maximum working distance of lensed PCF has been first revealed, agreeing well with the numerical solutions. Our specific lensed PCF can be experimentally optimized in terms of the collapsed PCF length and fiber tip curvature by use of a graphite filament furnace. A maximum collimating working distance up to 4.84 mm for a lensed PCF with the diameter of 125 μm is demonstrated, which is more than four times as long as previous lensed PCFs. The ultrawide working bandwidth over 770 nm is also demonstrated. The significantly enhanced features in terms of key performance parameters such as working distances and bandwidth will accelerate a variety of applications using such ultrathin lensed PCFs.

Ultrathin Lensed Photonic Crystal Fibers with Wide Bandwidth and Long Working Distances

Influence of positioning errors of the laser collimator on the beam shape and coupling efficiency

Allowable aperture considerations for laser diode coupling to cylindrical lensed fiber: Efficiency computation with ABCD matrix

Optoelectronic packaging is an important component of optical communication systems. However, it is a challenge for the packaging equipment to simultaneously have multiple degrees of freedom (DOF), wide range, and high precision. In this article, a six-degree-of-freedom (6-DOF) compliant parallel platform with all these features is presented. This platform has a parallel basic structure with large-stroke flexible joints. Based on elastokinematic analysis, the inverse kinematics solution of the platform is derived, and the effectiveness of the platform is proved by analyzing the 6-DOF motion via finite element analysis. The reachable workspace of the platform is analyzed, and its solution process is simplified using the inverse distance weighted method. Furthermore, a prototype of the proposed platform is presented and its accuracy is evaluated through experiments. Error compensation is used to significantly improve the motion accuracy of the platform. A closed-loop control that uses optical power meters instead of a multi-DOF detection device is proposed for optoelectronic packaging. The performance of the prototype applied to the packaging of coaxial optoelectronic devices is also demonstrated by experiments. The results demonstrate that the 6-DOF compliant parallel platform can successfully carry out the optical alignment of optoelectronic devices.

A Six-Degree-of-Freedom Compliant Parallel Platform for Optoelectronic Packaging

The manufacturing cost of coaxial optical communication lasers mainly occurs during the packaging process, and the key technology of the packaging process is the coupling alignment of photonic devices. Therefore, a high-precision and high-efficiency alignment algorithm is of great importance to reduce the cost and improve the quality of coaxial optical communication lasers. The traditional alignment algorithm that is currently used has the following shortcomings: (1) it cannot achieve multidegree-of-freedom alignment at the same time; (2) it easily falls into a local extreme point. Particle swarm optimization (PSO) can achieve simultaneous alignment of multiple degrees of freedom, and it does not easily fall into a local optimum. According to the optical principle, the coupling efficiency function of a coaxial optical communication laser can be obtained. Then, PSO can be used to find the maximum value of the function. The simulation results showed that the PSO algorithm could locate 99% of the maximum optical power. Coupling search can be used for coaxial optical communication laser devices using PSO on packaged devices. The experimental results also proved that the PSO algorithm has high reliability and can realize multidegree of freedom simultaneous search.

Hongwei Xu

Papers

Review of the technology of a single mode fiber coupling to a laser diode

Allowable aperture considerations for laser diode coupling to cylindrical lensed fiber: Efficiency computation with ABCD matrix

A Six-Degree-of-Freedom Compliant Parallel Platform for Optoelectronic Packaging

Three degree of freedom automatic coupling alignment of coaxial optical communication laser