Mechanically formed loss-tunable long-period fiber gratings realized on the periodic arrayed metal wires

A new method to tune the peak loss of mechanically formed long-period fiber gratings (MLPFGs) is proposed. Periodic arrayed metal wires are used to obtain the gratings along a single mode fiber (SMF). Self-maintaining gratings are achieved by the bonding force of an UV-adhesive between two glass plates. The initial index modulation formed at room temperature creates a maximum attenuation of −9 dB and −12 dB for coated and uncoated SMF, respectively. By changing the temperature, the peak loss is tuned due to the large thermal expansion of the UV-adhesive. Thermally tunable characteristics caused by the coating layer of the SMF are also described and compared with the results of the device with an uncoated SMF.