We present theory and simulations for a spectral narrowing scheme for laser diode arrays (LDAs) that employs optical feedback from a diffraction grating. We calculate the effect of the so-called smile of the LDA and show that it is possible to reduce the effect by using a cylindrical lens set at an angle to the beam. The scheme is implemented on a 19-element LDA with smile of 7.6 μm and yields frequency narrowing from a free-running width of 2 to 0.15 nm. The experimental results are in good agreement with the theory.
© 2005 Optical Society of America
Lasers and Laser Optics
Original Manuscript: January 7, 2005
Revised Manuscript: April 8, 2005
Manuscript Accepted: April 13, 2005
Published: October 10, 2005
C. L. Talbot, M. E. J. Friese, D. Wang, I. Brereton, N. R. Heckenberg, and H. Rubinsztein-Dunlop, "Linewidth reduction in a large-smile laser diode array," Appl. Opt. 44, 6264-6268 (2005)