Flexible distributed-feedback colloidal quantum dot laser

Flexible distributed feedback colloidal quantum dot laser patterned by a submicron grating structure is reported. An exposed standard commercial blank digital versatile disk (DVD) was used as the mask to fabricate a submicron scale grating structure, providing a simple and low-cost approach. A UV transparent polymerisable host matrix, 1,4-cyclohexanedimethanol divinyl ether (CHDV), was then photo-cured to replicate the DVD grating structure and peeled off from the mask, resulting in a flexible grating. The thickness of the grating substrate can be controlled in the range of 50 to 300 μm. A frequency-tripled Q-switched Nd:YAG laser (5-ns pulse, 10-Hz repetition rate and 355-nm excitation wavelength) was then used to photo-pump the CQD sample. The emission evolution was investigated and a 4 mJ/cm2 lasing threshold was found, comparing favourably to other reports of CQD lasers. The polarisation of the laser emission revealed that the DFB CQD laser favours a linearly polarized (TE) emission. During the experiment, the laser performance, operating above lasing threshold at room temperature and ambient atmosphere, was stable over more than 10,000 pump pulses.