Vertical cavity surface emitting laser (VCSEL) is a strong candidate for short pulse generation among the other semiconductor lasers in the era of laser technology. A 1550 nm, low power VCSEL is excited under different current shapes and the chief laser parameters are found out. The concept of gain switching under various current profiles are utilized effectively to bring out maximum laser power with minimum pulse width, which are the essential factors for long haul high speed optical data transmission. For a haversine electrical current input with 3.7 Ith amplitude, a laser peak power of 2.2 mW at 57 ps pulse width is obtained. In the case of trapezoidal pulse, 67 ps pulse width is obtained for 2.6 Ith current amplitude. It is also observed that square pulse of amplitude 2 Ith produces short optical pulse of 0.887 mW peak power and 89 ps width which shows the best performance when compared to other forms of pulses discussed in this work at the same input condition.

Terahertz (THz) frequency sources such as quantum cascade lasers (QCLs) offer a variety of new applications in far-infrared frequency bands. For better understanding of their behavior, a device-specific modeling approach is used to predict the optical output power under current modulation and chip temperature. This letter reports the numerical simulation of gain switching to evaluate temperature dependence for short pulse generation in QCLs. Modified rate equations are used for self-consistent computation of emitted THz optical power from QCLs. The device emits at 116 µ m and is driven by various inputs such as haversine, tangential hyperbolic and square electrical pulses. From the simulation it is evident that the square input pulse requires the least magnitude current (0.83 A) at 15 K to generate pulses with minimum full width half maximum (FWHM). Moreover, when the peak amplitude of the square input signal is 1.01 A, it generates optical pulses with the least FWHM of 19.42 ps at 45 K. In the case of the haversine input with peak amplitude of 1.8A, a peak power of 27.86 mW is generated at 15 K.

The COVID-19 pandemic is changing the way we connect, communicate, and collaborate. the crisis rapidly re-shape both the “what” and the “how” of companies. Businesses now move to doing business online, that involves selling of products, generating leads and connecting with customers. The chatbot, a software application designed for human-like conversations, emerged as a trend that is helping to close the social distance gap between customers and businesses. Many business have incorporated the tool in their communication strategy, this paper aims to understand to what extent, tries to put-forward an understanding of chatbots marketing and the use of chatbots in online shopping process. Furthermore, the paper tries to speaks extensively about the design in such a way that it will peak its performance for user acquisition.