A tunable single-passband microwave photonic filter is proposed and demonstrated,based on a laser diode (LD) array with multiple optical carriers and a Fabry-Perot (F-P) laser diode.Multiple optical carriers in conjunction with the F-P LD will realize a filter with multiple passbands.By adjusting the wavelengths of the multiple optical carriers,multiple passbands are merged into a single passband with a broadened bandwidth.By varying the number of the optical carrier,the bandwidth can be adjusted.The central frequency can be tuned by adjusting the wavelength of the multiple optical carriers simultaneously.A single-passband filter implemented by two optical carriers is experimentally demonstrated.