Research On Optical Interconnection Module In Free Space Based On LTCC

With the development of information technology, high speed electronic devices are used widely, but electrical interconnections might not be able to satisfy the requirement of high speed information transmission. As its excellent immunity of electromagnetic interference, great suppression of crosstalk and wide bandwidth, optical interconnection is expected to replace the electrical interconnection as a new generation of interconnection technology. At present, optical fiber and optical waveguide are two applied and mature technologies of optical interconnection. Although researches of free space optical interconnection are still in primary stage, this is more attractive for optical interconnection.A module of free space optical interconnection in near range is developed in this thesis, which uses low temperature co-fired ceramic as the substrate. The testing results confirm the great transmission performance of the module, which is up to 2.5 Gb/s for free space optical interconnecting in near range.This dissertation focuses on the free space optical interconnection technology. Firstly, the research background, development status and basic principles of optical interconnection are presented. Secondly, the key technologies of free space optical interconnection achieving are introduced, such as LTCC technique, transmitter and receiver modules, and the transmission principle and property of differential transmission lines. The transmitter and receiver modules are the critical parts to implement free space optical interconnection. The laser transmitter and drive circuit of transmitter module are discussed, as well as the laser detector, preamplifier, main amplifier and buffer circuit of receiver module. Thirdly, the basic characteristics of Gauss beam which is the laser transmitted from laser transmitter are presented, such as light intensity and light power. Then, the transmission loss of Gauss beam in free space is obtained by simulation. Fourthly, the overall design scheme of a free space optical interconnection module is proposed, including the chip selection of transmitter and receiver modules, the installation and overall arrangement of optical transceiver pins. There also have two practical approaches for alignment and installation of optical transceiver. Finally, the testing principle and process of the free space optical interconnection module is presented. The testing performances of the developed module are better than design targets. It is concluded from testing results that the change of matching resistance can improve the transmission efficiency. Furthermore, the most effective way is controlling the impedance and placing the differential lines strictly according to the high speed differential line rules. This work provides a significant guidance for further researches of free space optical interconnection.