Losses in semiconductor waveguide S bends fabricated by impurity-induced layer disordering.

Area of Science:

• Semiconductor physics
• Optoelectronics
• Materials science

Background:

• Gallium arsenide-aluminum arsenide (GaAs-AlAs) superlattices are crucial for optoelectronic devices.
• Waveguide design impacts signal loss in integrated photonic circuits.
• Impurity-induced layer disordering is a method for fabricating buried waveguides.

Purpose of the Study:

• To experimentally compare the optical losses of S bends fabricated using impurity-induced layer disordering in GaAs-AlAs superlattices.
• To evaluate the performance of different S bend geometries (raised cosine vs. constant radius).

Main Methods:

• Fabrication of S bends in GaAs-AlAs superlattices via impurity-induced layer disordering.
• Experimental measurement of excess loss in single-mode S bends with varying geometries.
• Comparison of transition lengths for a 3-dB excess loss threshold.

Main Results:

• Transition lengths for a 3-dB excess loss were approximately 290 microm for raised cosine S bends and 335 microm for constant-radius S bends.
• The fabricated buried-channel S bends exhibited favorable loss characteristics.
• Losses were found to compare favorably with those of S bends formed from rib waveguides.

Conclusions:

• Impurity-induced layer disordering is an effective technique for fabricating low-loss S bends in GaAs-AlAs superlattices.
• The raised cosine S bend geometry offers slightly lower transition loss compared to constant-radius designs.
• These buried-channel bends present a viable alternative to rib waveguides for integrated photonic applications.