Single transverse–mode operation of broad area–coupled waveguide lasers enabled by parity‐time (PT) symmetry is demonstrated. The PT‐symmetric laser operates on coupled waveguide cavities with electrically tuned gain and loss. Such a counterintuitive waveguide design enables PT‐symmetric breaking, causing unique mode selection and ultimately enables single‐mode operation. By electrically tuning the loss in the loss region of the coupled waveguide cavity, several different PT‐symmetric phases are analyzed theoretically, and the corresponding PT‐symmetric phase transition is demonstrated experimentally in the coupled waveguide laser.
InAs quantum dot (QD) laser heterostructures have been grown by molecular beam epitaxy system on GaAs substrates, and then transferred to silicon substrates by a low temperature (250 C) Pdmediated wafer bonding process. A low interfacial resistivity of only 0.2 X cm 2 formed during the bonding process is characterized by the current-voltage measurements. The InAs QD lasers on Si exhibit comparable characteristics to state-of-the-art QD lasers on silicon substrates, where the threshold current density J th and differential quantum efficiency g d of 240 A/cm 2 and 23.9%, respectively, at room temperature are obtained with laser bars of cavity length and waveguide ridge of 1.5 mm and 5 lm, respectively. The InAs QD lasers also show operation up to 100 C with a threshold current density J th and differential quantum efficiency g d of 950 A/cm 2 and 9.3%, respectively. The temperature coefficient T 0 of 69 K from 60 to 100 C is characterized from the temperature dependent J th measurements. V
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.