Research Projects

A temporal soliton is a pulse that maintains its profile on propagation through a medium. Temporal solitons in optical fibers, which arise due to a balance between the anomalous dispersion and Kerr nonlinearity, were first observed in 1980 by Mollenauer et al [1]. Optical solitons are typically created using ultrashort pulses from a mode-locked laser (MLL). The pulse train from a MLL is equivalent to a comb in the frequency domain. This simple relationship between the time and frequency domain response of mode-locked pulses led to breakthrough discoveries in the last two decades of the twentieth century, which resulted in 2005 Nobel prize in Physics [2] to Theodor W Hänsch [3,4] and John L Hall [5,6] for frequency comb metrology. Since then, the field of frequency combs has emerged as a frontier research area in physics and has led to several breakthrough developments in fundamental and applied physics [7-15]. Figure 1 shows the evolution of frequency combs over the last six decades. The early combs were generated from bulky MLLs, which give stable comb lines. After the 2005 Nobel Prize for frequency combs, a major research thrust for creating compact frequency combs started. In 2007 [16], frequency combs were demonstrated, for the first time, in a compact platform exploiting the Kerr effect in microresonators [17-19]. These microresonator combs, however, have large noise which makes them less superior to MLL-based combs. It took nearly six years to achieve the more stable and low-noise microcomb solitons, which were first observed in 2013 [20,21]. The work proposed in this project is motivated by the discovery of microcomb solitons, which are driving the development of new technologies [22] and precise measurement of time through development of optical atomic clocks and fundamental physical constants e.g. fine structure constant.

Frequency combs, Kerr nonlinearity, Microresonators, Brillouin scattering, Soliton combs, Nonlinear Optics