Periodically poled potassium niobate for second-harmonic generation at 463 nm

Abstract

We report on the fabrication and characterization of quasi-phase-matched potassium niobate crystals for second-harmonic generation. Periodic 30-mum -pitch antiparallel ferroelectric domains are fabricated by means of poling in an electrical field. Both birefrigence and periodic phase shift of the generated second harmonic contribute to phase matching when the d(31) nonlinear optical tensor element is used. 3.8 mW of second-harmonic radiation at 463 nm is generated by frequency doubling of the output of master-oscillator power-amplifier diode laser in a 5-mm-long crystal. The measured effective nonlinear coefficient is 3.7pm/V. The measured spectral acceptance bandwidth of 0.25 nm corresponds to the theoretical value.

Optical Parametric Generators and Amplifiers

“…4 shows the distribution of the MIR power in PPKTP optical parametric oscillator generating 1.5 W of average power in a 1.72 µm signal and a 2.789 µm idler [46]. Recently, this family of oxide ferroelectrics, where QPM structures have been realized and are of interest for the MIR spectral region, was joined by KNbO 3 [47] and near-stoichiometric compositions of LiNbO 3 [48] and LiTaO 3 [49,50]. The latter crystals are substantially easier to pole than their congruent counterparts.…”

Quasi-Phase-Matched Third Harmonic Generation in Optical Fibers Using Refractive-Index Gratings

“…The application of this idea for effective generation of the second harmonic has been first theoretically studied in [13], [14]. In recent works the grating-assisted generation of the second harmonic has been demonstrated experimentally in lithium niobate waveguide periodically poled by applying an external field in [15], and also in potassium niobate [16], GaAs-AlAs superlattice waveguide [17] and in silica glass fiber [18]. More recently, the QPM method has been applied to generate coherent extreme-UV light through a modulated hollow-core waveguide filled with various gases [19].…”

Efficient second-harmonic generation of ultrashort pulses with simultaneous quasi-phase matching and group velocity matching in periodic 90° domain structures of potassium niobate

“…Several ferroelectric materials, such as MgO-doped lithium niobate (LiNbO 3 ) [7], potassium titanyl phosphate (KTiOPO 4 ) [9], and potassium niobate (KNbO 3 ) [10], were used to achieve an efficient broadband frequency doubling using the method. KNbO 3 is one of the most attractive materials for high-power application of QPM devices because it has large nonlinear optical and electro-optical coefficients, high resistance to photorefraction, an extremely low coercive field (<0.5 kV/mm) for domain inversion [11][12][13], and wide optical transparency from 0.4 to 5.0 lm [14]. The ideal structure for QPM is a 180°domain inverted periodic structure.…”