We demonstrated a mode-locked fiber laser based on a novel photonic device that combined optical microfiber coupler (OMC) and saturable absorption materials. The stable ultrafast laser was formed based on the interaction between the deposited Indium Antimonide (InSb) and the evanescent field on OMC. Different from optical microfiber (OM), OMC can directly output the mode-locked laser without additional beam splitting devices, which further improves the integrated characteristics of the fiber laser. The pulse duration of the output pulse is 405 fs at the central wavelength of 1560 nm. To the best of our knowledge, this is the first time that optical microfiber coupler based saturable absorber (OMC-SA) for mode-locked fiber laser is demonstrated.

We report, for the first time, the nonlinear absorption at the 2 µm waveband of three Sb-related materials including two Sb compounds, GaSb and InSb, and one Sb alloy, Ge₈Sb₉₂. These saturable absorbers (SAs) were coated on tapered single mode fibers by the magnetron-sputtering deposition method. By incorporating these SAs into Tm-doped fiber lasers, ultrafast mode-locked solitons could be readily obtained. Stable pulse trains with 922 fs/753 fs/1005 fs pulse durations, 31.35 mW/37.70 mW/16.60 mW output powers, 93 dB/80 dB/92 dB signal-to-noise ratios were achieved with GaSb/InSb/Ge₈Sb₉₂, respectively. Our findings demonstrate that these materials can be widely used for photonic devices in the 2 µm waveband where ultrafast optical switching and modulating are desired.

In an effort to realize a compact and integrated ultrafast fiber laser system, we propose a fiber component serving as a wavelength division multiplexer (WDM), output coupler (OC), and mode-locker by a magnetron-sputtering saturable absorber (SA) on a laboratory-tapered coupler. With the function-integrated coupler, an Er-doped mode-locked fiber laser with 112 MHz repetition rate, 286 fs pulse width, and 87 dB signal-to-noise ratio (SNR) is demonstrated. The noise feature of the mode-locked laser is also characterized. To the best of our knowledge, this is the first demonstration of a mode-locked fiber laser based on a WDM/OC/SA integrated device.

Operation stability is the main challenge that current existing saturable absorbers (SAs) are facing. In this paper, we report on two low chemical activity saturable absorbers, the tellurium dioxide and antimony trioxide thin film, for stable femtosecond pulse generation in 2 μm region. The nonlinear absorption of two oxides at 2 μm was firstly revealed and the extraordinary mode-locking performance based on two oxides was demonstrated. The phase noise and amplitude noise were also measured and analyzed, and the integrated RMS relative intensity noise was found to be 0.0196% and 0.0218% for TeO ₂ thin film and Sb ₂ O ₃ thin film respectively. Great thermal stability and long-term stability were also confirmed. Heating the oxides coated area in atmosphere for hours and the lasers still could be mode-locked. Compared to low dimensional materials, the oxides proposed in this paper could be more suitable for robust mode locking in harsh environment. The broadened working conditions tolerance also enables new applications for optical modulators.

Metasurfaces integrated with high-performance films exhibit unique optoelectronic properties and hold great potential for applications in terahertz detection. Achieving high responsivity, sensitivity, and frequency-selective detection all at once remains a major challenge for current terahertz detectors. This study developed a droplet-shaped frequency-selective terahertz detector for 6G technology, aiming to meet the demands for high performance and frequency-selective responsiveness. By utilizing a unique droplet-shaped structure and incorporating a three-layer structure of magnetically responsive materials, this detector achieves highly efficient frequency-selective detection of magnetic gain. The characteristic frequency response at 0.1 THz is enhanced by using an external magnetic field and the localized surface plasmon (LSP). The experimental results indicate that the detector has a responsivity of up to 2522 MV/W, sensitivity as low as 2.11 pW/Hz ^0.5 , under the same conditions (with 0.145 mT), the response time is only 1.8 ns, offering new insights into the functionalities and performance of 6G detectors and promising widespread development in future communication technologies.

Blood sugar is an important biomedical parameter of diabetic patients. The current blood sugar testing is based on an invasive method, which is not very friendly for patients who require long-term monitoring, while the non-invasive method is still in the developing stage. In this paper, we design a non-invasive and highly sensitive terahertz wave detector with Co₃Sn₂S₂ semimetal thin film to test sugar concentration. As different concentrations have inconsistent responses to terahertz wave, we can deduce the concentration of the sugar solution to realize real-time highly sensitive detection of blood sugar concentration. This novel method can be further expanded to 6 G edge intelligence for non-invasive and real-time monitoring of blood sugar, and promote the development of 6 G technology.