Abstract
A single-fanout cascaded grating quasi-phase-matched nonlinear optical monolithic crystal and wavelength conversion and tunable laser system using the same are disclosed. The monolithic crystal includes a quasi-phase-matched single period grating having a first grating period along a first direction; and a quasi-phase-matched fanout grating having a second grating period along the first direction, wherein the second grating period is tunable along a second direction, the level of the second grating period continuously varies depending on the displacement of the crystal along the second direction, and the first direction is perpendicular to the first direction. By cascading the single period grating with the fanout grating, the wavelength conversion of the laser can be performed at a constant temperature or within a specific temperature range. When a laser system employs such monolithic crystal, although the single-fanout cascaded grating quasi-phase-matched nonlinear optical monolithic crystal is kept at a constant temperature, the most appropriate grating period can be selected continuously by moving the position of the crystal transversely (i.e. along the second direction). Whereby, the quasi-phase-matched conditions of two gratings are reached so as to achieve the purpose of converting the wavelength continuously. In addition, the wavelength of the laser can be converted in wider wavelength range by changing the temperature of the crystal and matching the single period grating with the grating period of the fanout grating.