Integrated channel-shared optical true time delay line array based on grating-assisted contradirectional couplers for phased array antennas

The grating-assisted contradirectional couplers based delay line attracts a lot of attentions due to its advantages of continuously tunable delay, low insertion loss and fast beam switching. Though much progress in single delay line has been made, there are still several problems yet to be solved in the multi-channel delay lines array, such as overlong chip length and large chip footprint. In this paper, channel-shared delay line array is proposed to solve above problems based on cascade delay line and inserted power divider. For 6 channels array, the channel-shared delay line array in this paper has only 1/3 chip length and 1/3 footprint of the channel-separated delay line array adopted in other literatures. Beside, we simulated the transmission and group delay spectra of a channel-shared 6-channel delay line array, all the channels show a same passband between 1544 nm to 1556 nm, the inter-channel delay differences are almost equal and can be tuned by the wavelength of light carrier.