The paper reports on novel effects exhibited by closely coupled twin-stripe lasers, Two forms of bistability have been observed. One effect is possibly caused by switching of waveguiding mechanisms from gain guiding to self-focusing. The second mechanism exhibits a large shift in near-field distribution from one side of the laser to the other. The speed of this bistable switching has been found to be between 800 and 900 ps. The effect of optical injection on bistability is also noted. Finally, twin-stripe lasers allow picosecond pulses as short as 20 ps to be generated, and the paper records the dependence of picosecond pulsewidth on asymmetric waveguiding.