Rhenium Disulfide (ReS₂) has evolved as a novel 2D transition-metal dichalcogenide (TMD) material which has promising applications in optoelectronics and photonics because of its distinctive anisotropic optical properties. Saturable absorption property of ReS₂ has been utilized to fabricate saturable absorber (SA) devices to generate short pulses in lasers systems. The results were outstanding, including high-repetition-rate pulses, large modulation depth, multi-wavelength pulses, broadband operation and low saturation intensity. In this review, we emphasize on formulating SAs based on ReS₂ to produce pulsed lasers in the visible, near-infrared and mid-infrared wavelength regions with pulse durations down to femtosecond using mode-locking or Q-switching technique. We outline ReS₂ synthesis techniques and integration platforms concerning solid-state and fiber-type lasers. We discuss the laser performance based on SAs attributes. Lastly, we draw conclusions and discuss challenges and future directions that will help to advance the domain of ultrafast photonic technology.

Schmitt triggers are electronic comparators that are widely used to enhance the immunity of circuits to noise and disturbances and are inherent components of various emerging applications. Conventional Schmitt triggers, composed of operational amplifiers, suffer from some inevitable drawbacks which are not prominent in CMOS Schmitt triggers. In this paper, a review on the advancement of Schmitt trigger circuits are illustrated in different literatures is discussed with their merits and demerits.

A scheme, using two-single drive Mach–Zehnder modulators (SD-MZMs) to generate flat optical frequency comb (OFC) by an analogue driving signal, is experimentally demonstrated. The modulator is used to add equidistant sidebands to an injected carrier continuous-wave laser centred at 1550 nm. The flatness of the comb lines is achieved by tuning the DC bias voltages supplied to both modulators. Five comb lines are tested for different frequency spacing of 8.5, 10, 11.5, and 12 GHz and show good frequency tunability. Also, the effect of increasing the radio frequency (RF) modulation signal power on the number of comb lines is investigated. A total of 5 comb lines are obtained with a repetition rate of 10 GHz and 0.77 dB flatness. The proposed system is simple and cost-effective due to the utilization of a simple Mach–Zehnder modulator structure driven by one RF signal generator.