Deok Woo Kim

Currently at PhD student
Ultrafast lasers and Photonics Laboratory (ULPL), Lab homepage (URL)
Department of physics, KAIST
Supervisor: Fabian Rotermund
Contact
dwkim96@kaist.ac.kr / ys89827@hotmail.com
Personal instagram (URL)

Research Interests

Solid-state lasers

Solid-state lasers are currently widely used in optical science, material science, and industry applications. Specially mode-locked lasers are actively applied in a wide range of optical science research fields, such as optical atomic clocks, ultrafast pump-probe spectroscopy, and frequency comb metrology, due to their superior properties, including equidistant frequency mode spacing, ultrashort pulse duration, and wide spectral bandwidth.

Recently, I have been particularly interested in transitioning from continuous wave operation to mode-locked pulsed operation using solid-state laser gain medium with an ultra-compact laser cavity size.

Waveguide lasers

Recently, femtosecond laser-inscribed waveguide platforms in crystalline optical active media have garnered considerable interest for enhancing laser efficiency and miniaturizing optical cavities up to a few centimeters.

I am particularly interested in the dynamic operations of ultra-compact laser systems, ranging from Q-switched to mode-locked operations in waveguide laser systems.

Quadratic/Cubic nonlinear optics

Since the 1990s, cascading nonlinear optical frequency conversion and its application techniques have been an essential part of the optical science field, requiring wavelength tunable properties.

I am especially interested in periodically poled lithium niobate (PPLN), a quasi-phase matched ferroelectric crystal, because it has a very high nonlinear optical coefficient (~30 pm/V) compared to other crystals such as KTP, KDP, and BBO. And we can control the converted frequency simply by changing the crystal temperature and poling period.

Dielectric thin film metrology

High-precision measurement of dielectric thin film parameters (refractive index and thickness) ranging from hundreds of nanometers to several micrometers is necessary and a challenging process. For example, precise phase shift control in a nonlinear optical process must be based on exact refractive index information.

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

Computational physics

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.