A micro light-beam spot-size converter using a hemicylindrical GRIN-slab tip with high-index contrast

Author

Shiraishi, Kazuo ; Tsai, Chen S.

Author_Institution

Graduate Sch. of Eng., Utsunomiya Univ., Japan

Volume

23

Issue

11

fYear

2005

Firstpage

3821

Lastpage

3826

Abstract

A simple light-beam spot-size converter (SSC) using a microscale graded-index (GRIN)-slab tip with a hemicylindrical endface for efficient coupling between a single-mode fiber and a fine-core waveguide is reported. Numerical examples based on the finite-difference time-domain (FDTD) method have shown that the tip made of a-SiO_x:H is capable of coupling a narrow field, 0.5 μm in radius at a wavelength of 1.55 μm, to a 5.3-μm radius standard single-mode fiber with a coupling loss as low as 0.07 dB. A micro GRIN slab with an index difference of as much as 34% was successfully fabricated. It has been confirmed experimentally that a GRIN slab with a hemicylindrical endface of 27-μm radii, a thickness of 33 μm, and a length of 35 μm, is capable of converting a spot radius of a single-mode fiber (5.3 μm) into a spot radius of 1.1 μm at a wavelength of 1.55 μm.

Keywords

finite difference time-domain analysis; gradient index optics; laser beams; micro-optics; optical fabrication; optical fibre couplers; optical fibre losses; refractive index; 0.5 mum; 1.1 mum; 1.55 mum; 27 mum; 33 mum; 35 mum; 5.3 mum; coupling loss; finite-difference time-domain method; hemicylindrical GRIN-slab tip; light-beam spot-size converter; optical fabrication; single-mode fiber; Coupling circuits; Finite difference methods; Guidelines; Optical beams; Optical coupling; Optical fibers; Optical waveguides; Planar waveguides; Slabs; Time domain analysis; Optical beam focusing; optical fibers; optical propagation in nonhomogeneous media; optical waveguides; optical-fiber connecting; spot size;

fLanguage

English

Journal_Title

Lightwave Technology, Journal of

Publisher

ieee

ISSN

0733-8724

Type

jour

DOI

10.1109/JLT.2005.857741

Filename

1561413