Broadband Linearized Fiber Optic Transmitter Module

Communications applications have utilized the intrinsic broadband characteristics of analog fiber optic links for myriad purposes. Today's transmitter technology of choice for these broadband applications is an InP-based electro-absorption modulator (EAM), because of its record levels of integration, size, efficiency, dynamic range and bandwidth. However, due to the lack of availability of adaptive broadband linearization technology, the performance of applications using these links has been strictly limited. Linear Photonics, L.L.C., has successfully demonstrated that the linearity performance of EAMs can be improved dramatically using electrical predistortion circuitry. In other words, combining EAMs with inherently adaptive, broadband predistortion circuitry results in robust, compact and highly-linear transmitter modules. LPL proposes to provide a solution to the problem of limited broadband performance of analog fiber optic links by building a compact, hybrid-integrated 1-18 GHz transmitter module with RF input, optical output and DC power supply interfaces. The transmitter design will target 125 to 130 dB-Hz2/3 SFDR and will be inherently adaptive over bandwidth, temperature, and an input-modulating signal envelope. This module will be further enhanced by a highly-linear EAM that is optically linearized for improved even-order performance, as well as electronic predistortion circuitry that reduces odd-order nonlinearity to achieve the target SFDR.