Fabrication of low index contrast semiconductor based
photonic crystals
Mikael Mulot
Laboratory of Photonics and Microwave Engineering (FMI)
Department of Microelectronics and Information Technology (IMIT)
Royal Institute of Technology (KTH)
Electrum 229, 164 40 Kista
Sweden
ABSTRACT:
We demonstrate low-loss photonic-crystal (PC) waveguides realized in InP by
Ar/Cl2 based Chemically Assisted Ion Beam Etching. The waveguides are
obtained as line defects in a triangular lattice of holes etched through a
three-layer InP/GaInAsP/InP heterostructure. By optimizing the etching
parameters so that the physical and the chemical components are balanced we
succeed in obtaining holes deeper than 2 m even for a hole diameter as
small as 220 nm. The quality of the PCs etched by two different process
conditions are compared by using the shape and the position of one of the
mode-gap as an assessment tool. The measured transmission spectra indicate
that the PC waveguides etched with an optimized process exhibit losses
smaller than 1dB/100µm. This is to date the lowest loss value reported for
PC waveguides in semiconductor heterostructures at optical communication
wavelengths.