Tunable WDM filter with 0.8-nm channel spacing using a pair of long-period fiber gratings

A strain-tuned wavelength-division-multiplexing filter with 0.8-nm channel spacing has been demonstrated by using a pair of long-period optical fiber gratings. The response of a transmission spectrum to applied axial strain is studied theoretically and experimentally. A large operation bandwidth of over 20 nm and a linear tuning rate of -0.6 pm/μ/spl epsiv/ within a near 3-nm range have been achieved.