We report on demonstration of high energy pulse laser at 2 μm by employing a normal dispersion fiber attained by a waveguide dispersion engineering. The normal dispersion fiber has a W-type refractive index profile, with a Thulium(Tm)-doped core. In contrast to a strong anomalous dispersion at 2 μm in a step-index fiber, the design allows strong waveguide dispersion that can generate normal dispersion at the Tm emission band. Mode area scalability of this fiber is discussed under the normal dispersion requirement. The Tm-doped fiber (TDF) is deployed in a ring cavity to produce mode-locked pulses near 2 μm. Subsequently, the pulse is amplified with more than 27 dB gain through the normal dispersion TDF. The output pulse energy reaches up to ∼525 nJ at 1852 nm without pulse breaking due to the engineered dispersion. The achieved pulse energy is record high for all-fiber configuration near 2 μm, to our knowledge.

The photonic crystal fiber (PCF) with a bunch of air holes enclosing the silica core field has momentous and compelling attributes when compared with the ordinary single-mode fibers. In this work, both the birefringence and dispersion properties of a polarization-maintaining chalcogenide (ChG) photonic crystal fiber are numerically investigated by means of the finite element method. Through simulation, it is found that the birefringence of the proposed Ge 11.5 As 24 Se 64.5 PCF can reach as high as 0.03 when compared with the conventional fiber that has merely 5 × 10 −4 for wavelengths in the 2-10 μm range. The PCF is designed with zero-dispersion wavelengths for x-and y-polarized modes in the 2-10 μm range. It is also observed that over the entire MIR wavelength range, the GVD remains positive and has a maximum value of 30,000 ps 2 /nm-km. Hence, the proposed Ge 11.5 As 24 Se 64.5 PCF plays the dual role of acting as a very good polarizationmaintaining fiber due to its very high birefringence and an excellent dispersion-compensating fiber due to its large positive GVD. This Ge 11.5 As 24 Se 64.5 PCF serves as a very good candidate for ultra-broadband high bit-rate transmission. Supercontinuum generation is another important application of PCF. Supercontinuum generation is a generation of coherent and broadband light. SC generation in PCFs has several applications in optical coherence tomography (OCT), optical frequency metrology (OFM), pulse compression, and design of ultrafast femtosecond laser pulses.