Development Of Multi-channel Spatial Interconnection Optical Rotary Joint

The development of rotary joint is systematically described in this dissertation.The advantages and disadvantages of single channel fiber optic rotary joint (FORJ)and multi-channel FORJ are discussed in detail. The significance of developingmulti-pass rotary joint is analyzed. The influence of assembly misalignments on coupling efficiency of the FORJ isinvestigated in detail, including lateral misalignment, end separation, and angularmisalignment of the fiber collimator. The optical power coupling loss due to lateralmisalignment, end separation, and angular misalignment is modeled and calculated,respectively. The results showed that the coupling loss of this system is more sensitiveto angular misalignment than lateral misalignment. And the influence of endseparation on the order of centimeters can be neglected. Based on the abovetheoretical analysis, two kinds of single channel FORJs were designed using singlemode fiber collimator and multi-mode fiber collimator. The insertion loss due tomechanical misalignments and mechanical rotation are tested and analyzed in detail. Multi-pass spatial interconnect fiber optic rotary joint using dense wavelengthdivision multiplexing (DWDM) technique is proposed based on the fabricated singlechannel FORJ for high-speed optical signal transmission. This optical rotary joint cantransmit bidirectional optical signals. The insertion loss, channel isolation andmechanical rotation induced insertion loss variation of this multi-channel FORJ aremeasured. A new dual channel optical rotary joint has been proposed via infraredcoupling technique to transmit optical signals across rotational interfaces to ensurecontinuously transmitting signal for low-speed optical signal transmission.The major innovations of this dissertation are as follows: 1. The single channel fiber optic rotary joint was designed using C-Lens fibercollimator. Low loss signals transmission was realized. The insertion loss of themulti-mode FORJ is less than 1.71dB, the insertion loss variation due to rotation is0.29dB; the insertion loss of single mode fiber optic rotary joint is less than 1.68, theinsertion loss variation due to rotation is 0.35dB. 2. The structure of dual channel optical rotary joint using infrared technologywas proposed. The signals transmission capability is tested in different and sameoperating system between two computers. The results showed that the practical IItransmission efficiency of infrared optical rotary joint relates to the operating systemsof the transmitter and receiver. The effective bandwidth under Win 2000 is the highest,1.437 Mbps, in the same operating system. 3. Multi-pass spatial interconnect fiber optic rotary joint using wavelengthdivision multiplexing (WDM) technique is proposed based on the fabricated singlechannel FORJ. The feasibility of multi-pass spatial interconnect FORJ was tested onboth 1310nm and 1550nm wavelength bands. This FORJ has a simple structure,which can be implemented at low cost. It is found that the insertion loss and thecoupling variation due to rotation of bidirectional transmission system are almostunchanged compared to unidirectional transmission system.