No abstract

The zero‐dimensional metallic nanoparticles (NPs) have attracted tremendous attention in various areas owing to the collective oscillation of electron gas that couples with electromagnetic field, known as localized surface plasmon resonance (LSPR). In practical applications, the tailoring of LSPR effect is of significant importance for promising photonic devices with designed nanocomposite systems and enhanced optical properties. Ion beam technology has been demonstrated to be an efficient method to fabricate NPs embedded in dielectrics for LSPR tailoring and material modification. By manipulating the parameters of ion beams, the shape, size, and structure of NPs can be well controlled, which enables the dielectrics to possess novel linear and nonlinear optical properties. In this review, the latest research progress on the ion beam synthesis of various NPs is systematically summarized. The tailoring of linear and nonlinear optical properties of dielectrics by NPs is discussed in detail. Selected applications are presented to indicate the development of the plasmonic NPs in dielectric systems for photonic applications.

Plasmonic Au nanoparticles embedded in LiNbO3 crystals as efficient saturable absorbers to realize 74.1 ps mode‐locked laser pulse generation at 1 µm are reported. The system is fabricated by Au ion implantation and subsequent annealing, a well‐developed chip technology. The strong optical absorption band peaking at 640 nm is observed due to the localized surface plasmon resonance. Z‐scan investigation shows that the LiNbO3 crystals with embedded Au nanoparticles possess ultrafast saturable absorption properties at near‐infrared 1 µm wavelength. With this feature the Au nanoparticles embedded LiNbO3 wafer is applied as saturable absorber into a laser‐written Nd:YVO4 waveguide platform. Stable laser pulses at 1064 nm based on an efficient passive Q‐switched mode‐locking process, reaching a fundamental repetition rate of 6.4 GHz and a pulse duration of 74.1 ps, are obtained. Since LiNbO3 has broadband applications in various optical systems, this work opens the way to develop intriguing devices in LiNbO3‐based photonic circuits by using embedded metallic nanoparticles.

We report on the enhancement and modulation of nonlinear optical response in an Nd:Y 3 Al 5 O 12 (Nd:YAG) laser crystal through embedded silver nanoparticles (NPs) fabricated by Ag + ion implantation. The linear absorption spectrum of the sample clearly reveals a localized surface plasmon resonance (SPR) band from 350 to 700 nm correlated to the Ag NPs. By using the Z-scan technique with femtosecond pulses at a wavelength of 515 nm, which is considered as an optical excitation within the SPR band, the nonlinear refraction index reaches values as high as ∼10 –12 cm 2 /W, enhanced by ∼4 orders of magnitude in comparison to that of unimplanted Nd:YAG (without Ag NPs). In addition, it has been shown that embedded Ag NPs in the Nd:YAG host reveal saturable absorption signifying the nonlinear responses. We have also observed that the nonlinear absorption coefficients depend significantly on the excitation energy and can be modulated by varying the fluence of Ag + ions.

We report on the synthesis of embedded gold (Au) nanoparticles (NPs) in Nd:YAG single crystals using ion implantation and subsequent thermal annealing. Both linear and nonlinear absorption of the Nd:YAG crystals have been enhanced significantly due to the embedded Au NPs, which is induced by the surface plasmon resonance (SPR) effect in the visible light wavelength band. Particularly, through a typical Z-scan system excited by a femtosecond laser at 515 nm within the SPR band, the nonlinear absorption coefficients of crystals with Au NPs have been observed to be nearly 5 orders of magnitude larger than that without Au NPs. This giant enhancement of nonlinear absorption properties is correlated with the saturable absorption (SA) effect, which is the basis of passive Q-switching or mode-locking for pulsed laser generation. In addition, the linear and nonlinear absorption enhancement could be tailored by varying the fluence of implanted Au ions, corresponding to the NP size and concentration modulation. Finally, the Nd:YAG wafer with embedded Au NPs has been applied as a saturable absorber in a Pr:LuLiF crystal laser cavity, and efficient pulsed laser generation at 639 nm has been realized, which presents superior performance to the MoS saturable absorber based system. This work opens an avenue to enhance and modulate the nonlinearities of dielectrics by embedding plasmonic Au NPs for efficient pulsed laser operation.