title: Efficient, low-threshold collinear and noncollinear beta-barium borate optical parametric oscillators.
abstract: The performance of collinear and noncollinear pulsed barium borate optical parametric oscillators with third-harmonic Nd:YAG pumping is analyzed. The effects of tangential phase matching and pump Poynting vector walk-off compensation are shown to enhance noncollinear operation. However, we show that these effects are mutually exclusive for a typeI beta-barium borate optical parametric oscillator and furthermore that tangential phase matching is dominant. The selection of a collinear or a noncollinear configuration is determined by pump divergence and spot size as well as by crystal aperture. With a pump divergence of 4mrad, noncollinear operation is optimal. The highest slope efficiency, 37%, and the lowest threshold, 5mJ, are obtained with nearly perfect tangential phase matching. For a pump divergence of less than 2mrad and a similar spot size, collinear operation gives the lowest threshold, 3.2mJ, and the highest slope efficiency, 33%.
authors.forename: A L
authors.initials: AL
authors.lastname: Oien
authors.forename: I T
authors.initials: IT
authors.lastname: McKinnie
authors.forename: P
authors.initials: P
authors.lastname: Jain
authors.forename: N A
authors.initials: NA
authors.lastname: Russell
authors.forename: D M
authors.initials: DM
authors.lastname: Warrington
authors.forename: L A
authors.initials: LA
authors.lastname: Gloster