Experimental demonstration of PT-symmetric stripe lasers

Recently, the coexistence of a parity-time (PT) symmetric laser and absorber has gained tremendous research attention. While PT-symmetric lasers have been observed in microring resonators, the experimental demonstration of a PT-symmetric stripe laser is still absent. Here, we experimentally study a PT-symmetric laser absorber in a stripe waveguide. Using the concept of PT-symmetry to exploit the light amplification and absorption, PT-symmetric laser absorbers have been successfully obtained. In contrast to the single-mode PT-symmetric lasers, the PT-symmetric stripe lasers have been experimentally confirmed by comparing the relative wavelength positions and mode spacing under different pumping conditions. When the waveguide is half-pumped, the mode spacing is doubled and the lasing wavelengths shift to the center of every two initial lasing modes. All these observations are consistent with the theoretical predictions and well confirm the PT-symmetry breaking. (Figure presented.) .