Improvements relating to faraday-effect elements

Abstract

Abstract 1,269,102. Modulating light. NIPPON SELFOC CO. Ltd. 3 July, 1969 [5 July, 1968 (2)], No. 33664/69. Heading H4F. [Also in Divisions C1 and G2] A glass fibre suitable for use as a Faraday effect element, e.g. in an optical isolator, contains oxides of lead, silicon and one of thallium and caesium, the concentration of the thallium or caesium oxide decreasing towards the surface of the fibre so that the refractive index n r of the fibre decreases from the centre to the surface according to the law n r = n 0 (1 - ar<SP>2</SP>) where r is the distance from the fibre axis, n 0 is the refractive index at the axis and a is a constant, so that divergence of the light is minimized. The fibre may be straight and disposed within a helical electrical conductor (solenoid) or the conductor may be straight and disposed within a helical fibre, Figs. 3 and 4 (not shown). The fibre is produced from one of uniform refractive index by substituting some of its constituent ions by others having a smaller ratio of electronic polarizability to (ion radius)<SP>3</SP>, e.g. by immersion of glasses containing thallium, or thallium and sodium, or caesium and sodium, or terbium and thallium, in a KNO 3 bath at 400‹ C. The distribution of lead ions in at least two examples appeared unaffected by this method and Vedet's constant appeared to be substantially uniform across such fibres.

Inventors

• 👤 Teiji Uchida
• 👤 Motoaki Furukawa
• 👤 Shogo Yoshikawa
• 👤 Ichiro Kitano
• 👤 Ken Koizumi

Bibliographic Details