Low-noise diode-pumped intracavity-doubled laser with off-axially cut Nd:YVO_4

Abstract

Effective noise reduction in a diode-pumped intracavity-doubled Nd:YVO(4) laser is achieved with a novel cavity design in which a birefringent filter is formed with off-axially cut Nd:YVO(4) and KTP. 20-mW green output with relative intensity noise of less than -120 dB/Hz was obtained under 290-mW pumping by a broad-area laser diode.

A tunable single-frequency green laser based on a wedged Nd:YVO4 crystal and a KTP crystal

“…The light for the other oscillating modes, however, is elliptically polarized by the KTP crystal, so some loss occurs at the wedge facet of the Nd:YVO 4 crystal again. When the light is incident perpendicular to the KTP crystal, equation ( 1) becomes δ i = 2π∆nl/ λ i , which is the same as the expression of the phase difference in [9,12]. Considering both phase and polarization changes of each longitudinal mode, the Jones vector formalism is utilized to calculate the round-trip transmittance of the eigenvalues of the resonator including this form of birefringent filter.…”

“…A birefringent filter is composed of a polarization element and a phase-retardation element. In a 532 nm laser, the phaseretardation element is usually a birefringent KTP crystal, while the polarization element can be obtained in many ways, such as Brewster plate [8,9], a YVO 4 beam displacer [10], a Brewstercut Nd:YAG crystal [11] and an off-axis cut Nd:YVO 4 crystal [12]. Among these laser configurations with a birefringent filter, the first two resonators need to introduce an extra-element (a Brewster plate or a YVO 4 beam displacer) into the cavity; especially for high output power, two Brewster plates can be placed into the resonator to suppress the spatial hole burning [13,14], which greatly increases cavity complexity and intracavity-loss; a Brewster-cut Nd:YAG is suitable for laser crystals with a large volume, and an off-axis cut Nd:YVO 4 crystal has a low effective emission cross section, which results in a low output power.…”

A Nd:YVO₄/LBO Intracavity Frequency Doubling Laser Pumped by a Diode-laser

“…Among the many laser crystals suitable for DPSL, Nd:YVO 4 crystal has attracted much attention because of its excellent properties. It has become an ideal working material for small and medium power DPSL devices [6][7][8]. The 4 F 3/2 -4 I 11/2 level transition of Nd:YVO 4 crystal can produce 1.34m laser.…”

Suppressing the preferential σ-polarization oscillation in a high power Nd:YVO4laser with wedge laser crystal

“…The π-polarized lasing (lasing parallel to the c axis) is stronger in the Nd:YVO 4 crystal, compared with the σ -polarized lasing (lasing perpendicular to the c axis). [6] Lasers built with this crystal will therefore preferentially oscillate on the πpolarization and keep the polarization direction unchanged in the entire range of pump powers, in the absence of other effects that create a bias for the σ -polarization. [7,8] The stability of polarization direction is necessary for obtaining the robust unidirectional operation and the nonlinear phase-matching in intracavity frequency-doubling ring lasers.…”