Research On Compact Mode-locked Photonic Crystal Fiber Lasers And Source Of Correlated Photon Pairs

Photonic crystal fibers (PCF) bring new opportunities to many scientific research fields based on their unique structures and advantages. Due to the advantages of the low cost, compact structure, enhanced stability and high output power, passive mode-locking based on PCF advanced the popularization process of the femtosecond laser technology. The application in quantum information of photonic crystal fiber has become one of the most thriving research areas. Utilizing its advantages, and together with the stable ultrafast laser, PCF brought effective methods in producing compact and high efficiency correlated photon pairs. This dissertation mainly focuses on ways to realize high power, compact mode-locking PCF laser, and the production of correlated photon pairs by using PCF. Main points including:1. A new kind of high power mode-locking PCF laser with fiber facet output coupler is established by using Yb³⁺ doped large-mode-area photonic crystal fiber (LMAPCF). Semiconductor saturable absorber (SESAM) is used to achieve self-start passive mode-locking. One facet of the fiber is direct used as the cavity mirror, reducing the complexity of the bulk components, making the high power PCF laser more compact and practical to use. The numerical simulation of the PCF laser is established. The output properties of the laser system and the mode-locking mechanism in the cavity are analyzed through numerical simulation. The results of the simulation well fit the experimental results.2. Yb³⁺ doped LMAPCF mode-locked laser with fiber facet output coupler and gratings for the dispersion compensation is established. Output pulses with 3.1 W average power and 56 nJ pulses energy are directly obtained. The pulses width of direct output is 494 fs. Also, the output pulse width, spectral width, and central wavelength all can be tuned to some extend. The filter-induced breathing in spectrum and pulse width is studied.3. Yb³⁺ doped LMAPCF mode-locked laser works in all-normal dispersion regime is established. Output pulses with 2.6 W average power and 46 nJ pulses energy are directly obtained. The direct output pulse width is 1.9 fs, and can be external cavity compressed to 425 fs. Furthermore, by introducing narrow-band filter, LMAPCF mode-locked laser works in dissipative soliton regime is realized, with 828 fs direct output pulse and 30 nJ pulse energy. The peak power reaches to 36.6 kW.4. The different parameter's effect on the properties of four-wave mixing based on PCF is analyzed and also is studied experimentally. The experimental setup used for producing four-wave mixing in 800 nm wavelength by using PCF and pumped by Ti-sapphire ultrafast laser is established. Based on the configuration, the experimental setup used to probe the photons is established. The conditions appropriate to obtain high efficiency correlated photon pairs by using PCF are summarized through single channel photon counting. The experimental program of obtaining high efficiency correlated photon pairs in 1.04μm by using high energy compact LMAPCF mode-locked laser is introduced.