Abstract: For the status quo of traveling wave detector array which can synthesize output power but can't improve work bandwidth, this paper proposes a new L-type array detector. Using a capacitance, a photodiode, and two inductance in series to form a single array unit, the L-type array detector has a cascade cell array structure. The results show that L-type detector can carry on power synthesis of the RF output signal, increaseworking bandwidth to 67 GHz at the same time; Compared with the traditional photoelectric detector, the work bandwidth is tripled. The reasoning method proposed in this paper can be adopted to flexible design of ideal photodiodes, providing a theoretical foundation for future study of photoelectric detectors.