A femtosecond fiber laser based on Yb-doped single polarization large-mode-area photonic crystal fiber (LMA-PCF) is demonstrated. The photonic crystal fiber acts as laser gain medium. Since the single mode area of the fiber is an order higher than that of conventional fibers, the fiber nonlinearity is effectively scaled down, and much higher energy laser pulse output is achieved. The laser is based on a linear cavity design, and a piece of semiconductor saturable absorber mirror is used to initiate mode-locking operation. A pair of gratings are used as intracavity dispersion compensation, and the fiber laser operates in the stretched-pulse regime where the amount of net cavity dispersion is in the vicinity of zero. For negative net cavity dispersion, the laser generates 500 fs pulses with an average power of 400 mW at a repetition rate of 47 MHz (corresponding to a single pulse energy of 8.5 nJ), and the pulses are dechirped to 98 fs after extracavity dispersion compensation. For positive net cavity dispersion, the laser generates 1.76 ps pulses with a single pulse energy of 10.6 nJ, and the pulses are extracavity dechirped to 160 fs.