Distributed feedback semiconductor laser

Abstract

Abstract PURPOSE:To enable a distributed feedback laser to oscillate in a uniaxial mode up to a high output level, by correcting an equivalent refractive index or diffraction grating cycle of a region having intense optical intensity distribution so as to be smaller than that of a region having weak optical intensity distribution. CONSTITUTION:Diffraction grating 12 having lambda/4 phase shift is formed on an n-type InP substrate 11. Then, an n-type 1.3 mum GaInAsP optical waveguide layer 13, an undoped 1.55 mum active layer 14, a P-type InP clad layer 15 and p<+>type GaInAsP contact layer 16 for example are deposited in that order by means of liquid-phase epitaxy. The width of the optical waveguide stripe including the active layer is varied by means of an appropriate mask, exposure and mesa etching such that the width of a region 17a having a smaller distance between the lambda/4 phase shift position 12a and the cleaved face is smaller than the width of a region 17b having a larger such distance, by about o.15 mum for example. A BH (buried hetero) structure is provided and p electrode 19 and an n electrode 20 are formed. This element is then cleaved such that the lambda/4 phase shift position 12a is deviated from the center of the length of a resonator of 300 mum by 30 mum for example. Si3N4 single-layer films are applied on the opposite end faces.

Inventors

• 👤 Junichi Kinoshita
• 👤 順一 木下

Bibliographic Details