Abstract

Wideband continuously tunable single-frequency lasers are required in a wide range of spectroscopic, communications, and sensor applications. To date, tensile stress has been used to achieve continuous tuning in Bragg-grating fiber lasers.¹ Strain tuning yields a Bragg-wavelength change of approximately 1.2 nm/millistrain in the 1.55-µm regime and is limited by the fiber strength. Young's modulus for SiO₂ is 1.02×10⁷ psi (5.27×10⁸ Torr). For fiber proof tested at 100 kpsi (5.17 M Torr), a maximum strain of roughly 1% can be applied without degrading the fiber strength and eventually breaking the fiber. This limits tensile strain tuning to the 10-nm regime. Fiber strength limitations associated with tensile stress are relieved with compressive stress is implemented because silica is 23 times as strong under compression as it is under tension.² A single-frequency erbium-doped, Bragg-grating fiber laser that uses uniform compression to continuously tune over a 32-nm range while maintaining uniform power is described.

© 1995 Optical Society of America