Abstract: A fiber Chirped Pulse Amplification (CPA) laser system includes a photonics band gap (PBG) fiber to function as a compressor. The PBG fiber is spliced with a fiber end cap that has an core expander for increasing a mode area of the PBG fiber. With increased mode area, the laser system is enabled to sustain an increased damage threshold energy thus is capable of producing short pulse laser with higher pulse energy.