In this paper, we propose an off-axis tilted fiber Bragg grating (OTFBG) in which the grating structure is limited to one side of the fiber core cross section. The tilted grating planes are fabricated using a femtosecond laser with a phase mask. The wavelength range of the OTFBG cladding mode resonance could be twice that of a conventional tilted fiber Bragg grating with the same tilt angle. The resonance intensity of the OTFBG core mode is significantly enhanced. We also fabricate a serial-double-angle OTFBG (SOTFBG) and a parallel-double- angle OTFBG (POTFBG). The wavelength ranges of their cladding mode resonances are effectively extended. The SOTFBG and POTFBG with tilt angles of 5° and 10° possess a wavelength range of cladding mode resonances of approximately 120 nm. They are capable of measuring the surrounding refractive index (SRI) with a refractive index (RI) sensible range from 1.24 to 1.45. A significantly wide range of cladding mode resonances is achieved by an SOTFBG with tilt angles of 10° and 15°, which is as wide as 215 nm. The RI sensible range of this SOTFBG is estimated to be from approximately 1.00 to 1.41, thereby making it suitable for SRI measurements in both gaseous media and aqueous solutions.

We demonstrated a wide-range wavelength-tunable passively mode-locked fiber laser based on the fiber Bragg grating (FBG) fabricated by femtosecond laser as the wavelength selection element. A ring fiber cavity with the nonlinear-optical loop mirror as its saturable absorber was employed for mode-locking operation. The peak wavelength of the fiber laser was 1547.9 nm with a spectral full-width-at-half-maximum of 0.90 nm at room temperature. The pulse duration of the fiber laser was about 2.94 ps closed to the Fourier-limited pulse duration of 2.80 ps by assuming sech2 pulse shape. The repetition rate was 860.5 kHz and the pulse peak power was about 56.2 W. The wavelength tuning range of the fiber laser achieved 14.2 nm by varying the FBG temperature from 25 °C to 1000 °C.

Ehretia macrophylla fruit is a traditionally used but underutilized functional resource that is noted for its diverse phytochemical composition, which includes flavonoids and polyphenols. However, the systematic metabolic transformations that occur in the fruit during post-harvest storage—particularly those associated with its traditional processing into dark fruit tea—remain largely unknown, limiting efforts to optimize quality and processing strategies. In the study, to address this gap, we employed a widely targeted metabolomics approach based on ultra-performance liquid chromatography–tandem mass spectrometry (UPLC-MS/MS) to dynamically profile the fruit metabolome across four storage stages (T0, T4, T8, T12). A total of 1101 metabolites were putatively annotated, and day 8 (T8) emerged as a potential pronounced metabolic inflection point. From T8 onward, 30–40% of metabolites showed differential accumulation, characterized by a gradual rise in nutrition-relevant lipids, amino acids, and vitamins. In contrast, key antioxidant-related metabolites, including phenolics and flavonoids, increased transiently before T8 but declined sharply thereafter. These coordinated shifts correlated with an increased representation of lipid- and alkaloid-related metabolic pathways, whereas flavonoid-associated features showed a relative decline. Collectively, these findings provide insights into the biochemical processes potentially associated with fruit blackening and the marked decline in antioxidant capacity during traditional processing. Our study provides the first metabolic blueprint connecting traditional processing practices with phased metabolic remodeling, offering a scientific foundation for quality assessment and the development of informed post-harvest strategies for processing E. macrophylla fruit.