ABSTRACT
Large nonresonant effective nonlinear indices that are due to cascading have been observed by Z-scan and CCD camera measurements performed on quasi-phase-matched LiNbO(3). Positive and negative values of n(cascad)(2) were measured at temperatures symmetrically displayed with respect to the optimum phase-matching temperatures (2.39 x 10(-13) and -2.37 x 10(-13)cm(2)/W, respectively).
ABSTRACT
High-power single-spatial-mode near-IR laser diodes are mixed in periodically poled LiNbO(3) (PPLN) to generate broadly tunable mid IR-radiation. Conversion efficiencies to the mid IR up to 0.017%/W are demonstrated, and up to 31 microW of power is generated at the spectroscopically important 4.3-microm wavelength. We achieved broadband mid-IR tunability by mixing a wavelength-tunable laser-diode pump source with a fixed-wavelength master oscillator power amplifier laser-diode signal source in a PPLN sample that has a poling period that varies from 21.0 to 22.6 microm in the direction transverse to the beam propagation. We generated mid-IR radiation from 4.1 to 4.3 microm with these laser sources, using a fixed 22.0-microm period region of the sample.
ABSTRACT
An optical parametric amplifier (OPA) has been demonstrated in bulk, periodically poled lithium niobate and is shown to operate with a noise figure well below the classical limit. In contrast to conventional OPA's, this device uses quasi-phase matching to provide the coupling between the pump and the signal. Comparison of the measured performance with that of a theoretical model reveals that the main intrinsic contribution to the output noise is due to spatial and temporal mode mixing, which arises as a consequence of tight focusing of the incident beams. Factors that affect the performance of this amplifier are identified theoretically and their relative importance investigated for both amplification and squeezing.
