Mid-infrared Suspended Membrane Waveguide and Ring Resonator on Silicon-on-Insulator

Abstract

Theoretical and experimental studies of mid-infrared (mid-IR) suspended membrane waveguide (SMW) and suspended membrane ring (SMR) resonator are presented. An array of periodical holes beside the rib waveguide facilitates the local removal of buried oxide to form suspended membrane devices on silicon-on-insulator (SOI). The waveguide design is optimized in terms of hole size, etch depth, and bend radius to minimize device strain and optical loss. We calculate waveguide dimension to attain the wide low-dispersion ( <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$\pm$</tex> </formula> 100 ps/nm/km) bandwidth for the wavelength range from 2.0 to 8.0 <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$\mu \hbox{m}$</tex></formula> , and optical nonlinearity is also studied. The SMWs are fabricated on a commercial SOI wafer and characterized by an <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$\hbox{Er}^{3+} - \hbox{Pr}^{3+}$</tex></formula> codoped fiber laser at 2.75 <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$\mu\hbox{m}$</tex></formula> . Negligible bending losses are measured for a 40- <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$\mu\hbox{m}$</tex></formula> radius bend. The minimum waveguide loss of 3.0 <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$\pm$</tex></formula> 0.7 dB/cm is measured experimentally. The SMR resonator has a quality factor ( <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$Q$</tex></formula> ) of <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$\sim$</tex></formula> 10 000 and an extinction ratio of <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$\sim$</tex></formula> 13 dB in near-IR. In mid-IR, the resonator has a <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$Q$</tex></formula> of <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$\sim$</tex></formula> 8100.