dc.description.abstract | Optical parametric oscillators (OPOs) have been widely employed to achieve a wavelength tunable coherent light source for various applications such as spectroscopy, communication, and remote sensing. Besides the tunability, a narrow spectral-line operation of the light source is usually demanded for these applications. Therefore, in this thesis, we design and fabricate a monolithic APPLN which can simultaneously achieve bandwidth narrowing and tunable multi-wavelength coherent light output.
The laser system consists of three key elements including a Nd:YVO4 as laser gain medium, an EO Bragg PPLN as an active Q-switcher , and an EO APPLN simultaneously as an EO polarization mode converter (EO PMC) and an optical parametric generator. The EO Bragg PPLN is designed to diffract 1064nm light when applying electric field along z direction to pulse the 1064nm light. The APPLN EO PMC is designed to produce narrow-line and multi-wavelength output. When it is pumped by 1064nm and driven by certain electric field along y direction, the output spectrum can be manipulated to desired multi-peak spectrum.
In operation, the EO Bragg crystal is driven at 170V and its Bragg angle is 0.7°. Without driving electric field along y axis, the APPLN EO PMC produces optical parametric oscillator’s signal at 1532nm when pumped by pulsed 1064nm. The signal’s peak power is 296 Watts, pulse width is 3.8879 ns and the bandwidth is 1.5nm at diode pump of 5.083 Watts. After driving the APPLN EO PMC in different electric fields along y axis, the laser system can produce different peak numbers, besides of those are the narrow-line signals. When the EO PMC is driven by 200 V/mm along y axis, there is one peak in the spectrum and its bandwidth is narrowed to 0.2nm, which is 7.5 times narrower than the output bandwidth without applying Ey field. When the EO PMC is driven by 400V/mm along y axis, two peaks can be found as the desired design and its bandwidths of 0.3nm and 0.2nm can be obtained. The measurement results are corresponding with the calculated results at certain and designed y field. | en_US |