Optical isolator

Abstract

Abstract PURPOSE:To reduce the size of optical isolators, by longitudinally connecting the second and third optical fibers, each of which has a different refractive index distribution, to the optical fiber which is stuck a light absorbing substance on the side face of the tapered section and forms a spherical lens at the front end of the tapered section. CONSTITUTION:A converged type (GI) fiber 13 has a tapered section 17 and a light absorbing substance 12 is stuck on the side face of the tapered section 17. Moreover, at the front end of the tapered section 17, a spherical lens 16 is formed to make optical couplings with a semiconductor laser 11. Beams emitted from the laser 11 are converged into the core of the tapered section 17 by a lens 16. The lower grade mode light of the fiber 13 passes through a stepped index (SI) fiber 14, and is made incident the GI fiber 15. In the fiber 15, all modes are energized and the beam from the laser 11 behaves as shown by the solid line. A part of the beam is reflected by an end face of fiber 18 and proceeds as shown by the broken line. The reflected beam which proceeds along the broken line runs out from the core in the tapered section 17 and is absorbed by the substance 12. In this way, the fiber 14 is formed to have a diameter of several mm., and a sufficient isolation can be obtained.

Inventors

• 👤 Shigeru Oshima
• 👤 Takeshi Koseki
• 👤 Toshifumi Tamura

Bibliographic Details