Fabrication And Research Of Nanowires/microfiber Hybrid Structure Laser

Semiconductor lasers based on cadmium sulfide (CdS), zinc oxide (ZnO), cadmium selenium (CdSe) nanowires have gained considerable attentions. In previous studies, a semiconductor nanowire is not only a gain medium, but also acts as a laser cavity. However, due to the small diameter of the nanowire and the existence of substrate, significant evanescent field exists outside the nanowire body that may introduce significant losses and limit the quality factor (Q factor). On the other hand, further progress with these nanowire structures and their potential use as photonic circuit elements could be limited by poor control of the coupling of light into and out of the nanowires. Both theoretical and experimental works have shown the potential to achieve high Q factor optical cavities and low threshold lasers based on hybrid nanowire structures.Based on reviewing of the recent progress of micro-/nanofiber and microcavity laser, we systematically studied the mechanically fabrication of micro-/nanofiber, CdS nanowire and silica microfiber. hybrid laser and multicolor hybrid laser. Some innovative results were obtained:(1) In this paper, we build a mechanical system to fabricate MNFs which based on controlled flame and stepper motor. The controlled flame is hydrogen-oxygen flame which made by electrolysis water. We use hydrogen-oxygen flame to heat the fiber and at the same time using the stepper motor to draw the fiber. By single side drawing, we got a MNFs which had the diameter of 400 nm and the length of 400mm. By bilateral side drawing, we got a MNFs which had the diameter of 2μm and the length of 10mm. In addition, we have made some trying of laser-heated and electric taper drawing.(2) We made a hybrid structure laser based on CdS nanowire and microfiber which is fabricated by the mechanical machine as mentioned above. The diameter and length of the nanowire are 394nm and 49μm, respectively. And the diameter of the microfiber is 3.9μm. The pump source is a frequency-tripled neodymium doped yttrium aluminum garnet (Nd:YAG) laser (355 nm,6 ns, and 10 Hz). The exciting of the nanowires and the collection of the photoluminescence (PL) are implemented by means of evanescent coupling through the same silica microfiber. The wavelength is at the center of 518nm, the threshold is about 0.45pJ, the Q factor is 863, and the mode spacing is 0.42nm.(3) Similarly to the above structure, we attached a CdSe nanowire (153-μm-length, 977-nm-diameter), CdS nanowire (66.7-μm-length,370-nm-diameter) and ZnO nanowire (72.6-μm-length,306-nm-diameter) to a 3.3-μm-diameter silica microfiber. When pump energy higher than 1.3μJ, three spatially and spectrally distinct lasing groups can be measured at the same output port simultaneously.The hybrid laser provides low threshold and high efficiency due to the combination of high gain of semiconductor nanowires and high coupling efficiency. The approach can be extended to other materials to produce hybrid lasers that cover ultraviolet to near infrared spectral regions.