Solid-state blue laser offers extended tunability
Although continuous-wave blue diode lasers are available, output power, beam quality, and tunability are limited.
Although continuous-wave blue diode lasers are available, output power, beam quality, and tunability are limited. And although frequency doubling of Ti:sapphire laser output can provide tuning in the 400 to 500 nm range, both cost and complexity of this option are high. Using an alternative method based on second-harmonic generation in the cavity of a green-laser-pumped optical parametric oscillator (OPO), researchers at Institut de Ciencies Fotoniques and Institucio Catalana de Recerca i Estudis Avancats, both in Barcelona, Spain, have developed a blue, compact solid-state laser that offers practical output power, single-mode operation, and a wide tuning range.
A magnesium-oxide doped stoichiometric lithium tantalite (MgO:sPPLT) nonlinear crystal is placed between two concave reflectors and a bismuth borate (BIBO) nonlinear crystal is placed between two plane mirrors, comprising a ring OPO cavity. Temperature tuning of the MgO:sPPLT crystal varies the resonant signal wavelength (produced by the green laser at 532 nm pumping the cavity) from 850 to 978 nm, while angular tuning of the BIBO crystal produces the corresponding second-harmonic generation wavelength in the blue from 425 to 489 nm. The blue output has a power level ranging from 45 mW up to 448 mW. The tuning range can be extended to cover 300 to 530 nm using different gratings in the MgO:sPPLT crystal. Contact Majid Ebrahim-Zadeh at firstname.lastname@example.org.