Solid-state lasers have currently widely been used in optical science, material science and industry applications. Specially mode-locked lasers actively applied to wide optical science research field such as optical atomic clock, ultrafast pump-probe spectroscopy, frequency comb metrology due to its superior properties which are equi-distance frequency mode spacing, ultrashort pulse duration and wide spectral bandwidth.

Recently and specifically, I am interested in the continuous wave operation to mode-locked pulsed operation based on solid-state laser gain medium with ultra compact size laser cavity. 

Since 1990s, cascading nonlinear optical frequency conversion and its application techniques have been essential part of optical science field which require wavelength tunable property.

I am specially interested in the periodically poled lithium niobate (PPLN) which is quasi-phase matched ferroelectric crystal because this crystal has very high nonlinear optical coefficient (~30 pm/V) rather than other crystals (KTP, KDP, BBO etc.) and we can simply control converted frequency by changing crystal temperature and poling period. 

High precise measurement of dielectric thin film parameters (refractive index and thickness) ranging from hundres of nm to several micrometers are necessary and challenge process. For example, precise phase shift control in nonlinear optical process must be based on exact refractive index information.

I am specially interested in the precise measurement of dielectric thin film parameters (refractive index and thickness orders of 0.0001 and 10 nm) with a prism coupler whose structure is planar waveguide by analyzing excited waveguide mode in statistically. Also, we can obtain these same physical properties by analyzing interference fringe pattern in statistical analysis (Fringe method). 

Some experimental data or physical situations have difficulty in analyzing analytically, so we have to solve it by numerical computer simulations.

Specially,

– Excited waveguide mode analysis using statistical nonlinear least square method

– Optical pulse propagation or evolution by numerically solving the Nonlinear schrodinger equation with the Split-step Fourier method

– Optical eigen-mode profile analysis in waveguide by Finite-difference method.

– Solving all differential equations in optics written any forms.

My frequently used numerical calculator is MATLAB.