Ion-exchanged waveguides in periodically poled Rb-doped KTiOPO₄ for efficient second harmonic generation

Abstract

An ion-exchange process has been developed for periodically poled Rb-doped KTiOPO4 (RKTP) which warrants high efficiency and low loss channel waveguides. The domain stability was investigated, and it was found that domain gratings with uncharged walls could stand the ion-exchange process without deterioration. 3.1 mW of blue second harmonic light was generated from 74 mW of radiation at 940.2 nm coupled into an 8 µm wide and 7 mm long waveguide, corresponding to a normalized conversion efficiency of 115%/Wcm2. Waveguides in PPRKTP open the possibility for stable operation at high optical powers, as well as generating entangled photons at low optical powers, and enable the investigation of novel nonlinear processes such as counter-propagating interactions in a waveguide format.

Backward wave optical parametric oscillation in a waveguide

“…Currently, the most efficient KTP QPM waveguides are fabricated by first implementing the QPM grating through electric field poling, followed by waveguide inscription via ion exchange [12]. However, the finely pitched ferroelectric domains required for realizin g BWOPO are susceptible to back-switching at the high temperatures used for waveguide fabrication [26], which has hindered the development of waveguide BWOPOs.…”

3D Laser Writing of Low‐Loss Cross‐Section‐Variable Type‐I Optical Waveguide Passive/Active Integrated Devices in Single Crystals

“…[7,8] Among the various optical gain media, single crystals activated with rareearth (RE) ions have garnered significant attention as gain materials for WGs in integrated optics, due to their advantages, including low optical losses in visiblenear-infrared-mid-infrared band, excellent thermal conductivity and thermal mechanical performance, large damage threshold, large peak emission cross-section, and high doping concentrations. [9][10][11] Traditional methods for fabricating WGs in bulk crystals encompass techniques such as metal-ion diffusion, [12] ion exchange, [13] ion implantation, [14] and photolithography. [15,16] However, these methods exhibit limitations, including complex processes, low efficiency, high cost, stringent requirements for a complex vacuum environment, and inability to create 3D WG devices.…”

Infrared LiF ridge waveguide fabricated by carbon ion irradiation

“…Waveguide structures based on optical materials with different properties can be used as photonic devices with different functions, such as waveguide directional couplers, modulators, optical switches, optical amplifiers, waveguide lasers and frequency converters, etc [9,10]. Due to the important application value of waveguide structures, many methods have been developed to fabricate waveguide structures, including ion implantation, swift heavy ion irradiation, ion exchange, ion diffusion, thin film deposition, focused proton beam direct writing and femtosecond laser direct writing, etc [11][12][13][14][15][16][17][18][19][20]. Among them, ion implantation and swift heavy ion irradiation are two of the effective methods for fabricating a waveguide.…”