Chinese Journal of Lasers, Volume. 50, Issue 8, 0802401(2023)
Research Progress on Femtosecond Laser Fabrication of Nonlinear Photonic Crystals
The fabrication strategy for nonlinear photonic crystals has drawn substantial research interest because of their highly efficient nonlinear optical interactions. Femtosecond laser engineering has distinct advantages over conventional methods for the fabrication of nonlinear structures. These advantages include its high precision, resolution, and flexibility. This paper summarizes the research progress of femtosecond laser processing technology for constructing nonlinear photonic crystals and provides a brief introduction to the quasi-phase matching theory involved. The processing mechanism of femtosecond-laser-induced ferroelectric domain inversion and laser erasure of second order nonlinear polarization coefficients (
This paper summarizes the research progress of femtosecond laser processing technology for constructing nonlinear photonic crystals and also provides a brief introduction to the quasi-phase matching theory involved. The processing mechanism of femtosecond-laser-induced ferroelectric domain inversion and laser erasure of
Tightly focused femtosecond laser pulses can induce a thermoelectric field in the ferroelectric crystal that inverts the direction of spontaneous polarization. On the basis of this mechanism, an arbitrary arrangement of 2D inverted domains can be constructed to enhance the second-harmonic emission from the crystal, and quasi-phase-matching structures can be integrated in the LiNbO3 waveguide to achieve efficient frequency conversion (Fig. 4). This technique can also be used to fabricate 3D nonlinear photonic crystals in multi-domain/single-domain Ba0.77Ca0.23TiO3(BCT)/ Ca0.28Ba0.72Nb2O6(CBN) crystals, which demonstrate second harmonic diffraction with 3D quasi-phase matching (Fig. 5). Another technique that relies on the laser-induced amorphization of the crystal to partially erase
The spatial distribution of
While substantial progress has been made in the femtosecond laser processing of nonlinear photonic crystals, some challenges remain.
When processing inside the crystal, the aberration resulting from the mismatch of the refractive index causes an axial shift of the focal spot, which seriously limits the axial resolution as well as the fabrication quality of the structures. Reasonable diffractive optical components for aberration compensation must be implemented during fabrication. One method is to introduce a spatial light modulator into the femtosecond laser processing system, thereby eliminating the effect of aberration by loading a specific phase hologram.
To date, few attempts have been made to combine nonlinear photonic crystals with other optical devices to extend their functionalities. Various functional optical devices, such as electro-optic modulators, resonators, waveguides, and nonlinear frequency converters, can be integrated within a single ferroelectric crystal by combining the flexibility of the femtosecond laser and other processing techniques. The integrated photonic chip will exhibit more powerful functions in modern optical signal processing and quantum computing.
Currently,
In addition to the aforementioned development trends, certain topics, such as the development of a fabrication strategy with high efficiency to lay the foundation for mass production, must be investigated further. With improved femtosecond laser processing technology, nonlinear photonic crystals show promising prospects.
Get Citation
Copy Citation Text
Longfu Li, Leran Zhang, Liqun Xu, Xin Li, Changrui Liao, Yiping Wang, Dong Wu. Research Progress on Femtosecond Laser Fabrication of Nonlinear Photonic Crystals[J]. Chinese Journal of Lasers, 2023, 50(8): 0802401
Category: Laser Micro-Nano Manufacturing
Received: Jul. 18, 2022
Accepted: Aug. 31, 2022
Published Online: Apr. 14, 2023
The Author Email: Li Xin (lixinkiller@nudt.edu.cn), Liao Changrui (cliao@szu.edu.cn)