Narrow-band, tunable 2 μm optical parametric oscillator based on MgO:PPLN at degeneracy with a volume Bragg grating output coupler
Peter Koch, Felix Ruebel, Martin Nittmann, Thorsten Bauer, Juergen Bartschke and Johannes A. L’huillier, Apl. Phys B (2011), Vol. 105; No. 4, pp. 715.