Influence of Wavelength and Temperature Changes on Optical Performance of Fiber Joints With Small Gap

We have investigated the characteristics of optical fiber joints with a small gap over wide wavelength and temperature ranges. When there is a small air gap between fiber ends, the insertion loss increases between 0.0 and 0.6 dB over a wide wavelength range of 0.7–1.7$mu$m and a wide temperature range of$-$40$^circ$C to$+$80$^circ$C. The return loss varies greatly and the worst value is about 9 dB. The return loss depends on temperature with fiber end joints that employ index matching material. The value varies from more than 50 dB to a worst value of 35 dB at low temperature.