Gold Nanocluster‐Modified Titanium Nitride for Ultrafast Photonics Applications

Abstract

Transition metal nitride materials exhibit unique optical characteristics and have attracted much interest for various applications, including waveguiding, photovoltaics, and nonlinear optical devices. Herein, titanium nitride (TiN), as a typical representative of biocompatible transition metal nitrides, is prepared and modified with gold nanoclusters (Au NCs) for promoting the carrier mobility, and the corresponding physical characteristics are systematically characterized. The TiN‐based saturable absorber (SA) on microfiber is fabricated and its nonlinear optical absorption property is also studied experimentally. Furthermore, the TiN‐decorated SA is applied in an ultrafast fiber laser at the communication bands. The fiber laser can generate the stable ultrashort pulses with a pulse width of 1.66 ps, a fundamental repetition rate of 7.49 MHz, and a spectral bandwidth of 2.61 nm. More importantly, the chaotic multiple pulses can be obtained, which is reported for the first time in the fiber laser based on the TiN SA on microfiber as far as it is known. The chaotic multiple pulses show many interesting characteristics, including high average pulse energy, varying pulse separations, and pulse intensities. These results have proved that the TiN shows great potential in many fields, such as advanced optical‐intensity modulator, ultrafast pulse dynamics, and optical fiber communications.

Enhancement and Inversion of Absorptive Nonlinearity Induced by Topochemically Controlled Insulator-to-Metal Transition

“…Moreover, as a result of the reverse of absorptive nonlinearity induced by the increase in oxygen deficiency, we observe a crossover of nonlinear absorption coefficients (α NL ) for samples with moderate oxygen vacancies. The calculated NLO parameters, including α NL and Im χ 3 , are quite promising compared with those of contemporary low-dimensional absorptive NLO materials (see Table S2), suggesting that these topochemically engineered oxide NPs can be further exploited for applications like saturable absorbers for pulse laser generation …”

“…The calculated NLO parameters, including α NL and Imχ 3 , are quite promising compared with those of contemporary low-dimensional absorptive NLO materials (see Table S2), suggesting that these topochemically engineered oxide NPs can be further exploited for applications like saturable absorbers for pulse laser generation. 46 To unravel the response time for the NLO absorption, we employed femtosecond pump−probe spectroscopy to study the ultrafast carrier dynamics associated with the transient change in transmission. A degenerate pump−probe setup was used with the pump and probe wavelength fixed at 1030 nm.…”

Robust and High‐Efficient Fabrication of Gold Triangles Array on Optical Fiber Tip for Laser Mode Locking

“…Note that the fiber laser in our experiment has a large absolute value of net cavity dispersion (1.96 ps 2 ), revealing that the soliton pulses are not nearly transform limited. [ 49 ] From Figure 5d, the RF spectrum displays a high peak at the repetition rate of 2.07831 MHz, corresponding to a signal‐to‐noise ratio (SNR) of 45 dB, which indicates the high stability of the mode‐locked pulses.…”

Tyrosine-Decorated Gold Nanoclusters Chelated Cerium(III) for Fluorescence Detection of Dopamine

“…Then, to explore the mechanism of the link between GNC and Ce 3+ , some experiments for chemical structure analysis were performed, except for X-ray diffraction (XRD). It is considered that no crystal diffraction peak of nanoclusters could be observed in XRD because of their ultrasmall sizes. , In X-ray photoelectron spectroscopy (XPS), the peak corresponding to C–OH (285.3 eV) showed an increase after adding Ce 3+ , while the intensity of CO (286.5 eV) showed a relative decrease (Figure A,B). This was consistent with previous studies, suggesting the coordination interactions between carboxylic acid groups and Ce 3+ .…”