The amount of reflected light fed back in the coupling of semiconductor lasers and tapered hemisphericalend (TH) fiber is estimated. Reflection from incident hemisphere is estimated to be below -50 dB, from the loss in the coupling between the laser and its virtual image. For multimode TH fiber reflection of backward-propagating light from connections can be reduced to below -50 dB by an ~10-µm lateral displacement parallel to the junction plane; there is a small penalty in forward-coupling efficiency. The reduction of reflection is confirmed by measuring relative intensity noise of coupled laser light.
© 1983 Optical Society of America
Hideo Kuwahara, Yoshihito Onoda, Masami Goto, and Takakiyo Nakagami, "Reflected light in the coupling of semiconductor lasers with tapered hemispherical end fibers," Appl. Opt. 22, 2732-2738 (1983)