Optical transceiver sub-system package based on SiOB with 8×14Gbps two-way bandwidth

Abstract

In this article a parallel optical sub-system package is designed and fabricated. An 850nm vertical cavity surface emitting laser (VCSEL) array with a laser driver are used as the light sources of the transmitter, and a photodiode (PD) array with a trans-impedance amplifier plus limiting amplifier (TIA/LA) are used as the detectors of the receiver. Two chips including VCSEL array and PD array are integrated on a high impedance silicon substrate through flip-chip process. The solder bumps are planted on substrate as input and output electrical interface. Passive alignment with high coupling efficiency and large tolerance is achieved. Electrical design for high frequency and high density package is critical, due to the issues related to Signal Integrity (SI) and Power Integrity (PI). Electrical interconnection based on substrate for highspeed signal and power integrity are also analyzed. The assembly of sub-package based on silicon substrate and PCB is finished. And an 8×14Gbps SOP parallel optical transceiver is developed. The back to back eye diagram measured results shows that bit rate of each channel is able to reach up to 14Gbps. IntroductionParallel optical interconnect is a good choice to complete the short distance, high speed communication compared with copper and serial optical interconnect, and applied to meet the high bandwidth requirement of rack to rack and chip to chip. Parallel optical transmitter (TX) and receiver (RX) multi-chip module with 1310nm and 850nm wavelength has been covered. Multi-mode applications allow higher coupling tolerances that reduce the packaging costs that are quite high for photonic devices package at single-mode transmission. ASICs and microprocessors drive the need for parallel optical links for both high performance computing (HPC) in data centers and in consumer applications as high-definition multimedia interfaces (HDMI) [1][2]. This requires large bandwidths on the physical link layer. Protocol standards are evolving to meet higher performance requirements, Optical modules QSFP and CXP for Infiniband applications supporting multi-Gbps per channel have been proposed [3][4][5]. However, optical package is challenging because of combining thermal, electrical and optical design, process and reliability requirements. Generally speaking, two key parts determine the performance of an optical transceiver and cost. One is the optical design, which should provide for stable optical alignment between the electro-optic active elements and the fiber channels. The majority of current parallel optical transceivers are faced with the problem of complex structures. A combination of 45° mirrors to realize 90°optical links turning and micro lens r mounted on flexible PCB are widely

A Surface Mounting Embedded Optical Transceiver with Bi-Directional Data Rate of Eight Channels × 10 Gbps

“…Compared with the embedded module with a BGA solder interface, these differences are apparently brought about by the mechanical connector. The performance of the traditional pluggable optical transceiver is thus limited by connecter performance and pluggable electrical interface, which was analyzed in [4]. Figures 7a and 7b show the complete optical transceiver mounted on the test board and the experimental test platform for eye diagram measurement and the bit-error rate (BER) of the embedded optical transceiver.…”

“…Optical modules SFP, QSFP, and CXP for Infiniband applications supporting multi-Gbps per channel have been proposed [3][4][5]. However, these pluggable optical transceivers can only be deployed at the board edge and require extra connectors, which bring multiple impedance mismatches and seriously deteriorate the channel transmission characteristic [4]. To get rid of the mechanical connectors and optimize system performance, some non-standard module and opto-electronics integration have been researched [6][7][8].…”

“…Protocol standards are evolving to meet higher performance requirements, for example, 100-gigabit Ethernet, Peripheral Component Interconnect Express Gen4, and Infiniband 100 Gigabit, which involves an optical links solution proposal [1,2]. Optical modules SFP, QSFP, and CXP for Infiniband applications supporting multi-Gbps per channel have been proposed [3][4][5]. However, these pluggable optical transceivers can only be deployed at the board edge and require extra connectors, which bring multiple impedance mismatches and seriously deteriorate the channel transmission characteristic [4].…”