Compared with traditional WDM network, OFDM-based flexible optical networks are able to provide better spectral efficiency due to its flexible allocation of requests on finer granularity subcarriers. Survivability is a crucial issue in OFDM-based networks, although little work has been done in this topic. In this thesis, a survivable multipath provisioning scheme is presented, which provides flexible protection levels to individual demands in OFDM-based flexible optical networks. We also define the static Survivable Multipath Routing and Spectrum Allocation (SM-RSA) problem which aims to accommodate a given set of demands with minimum spectral utilization. We show that the static SM-RSA problem is NP-hard and provide ILP formulation for it. Also, an efficient heuristic algorithm is given to solve the problem. Our simulation results of both ILP solution and heuristic method show that the proposed multipath provisioning scheme achieves better spectral efficiency than the traditional single path provisioning scheme.