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Proceedings ArticleDOI

Tapering and size reduction of single-mode silicon waveguides by maskless RIE

02 Jul 2012-pp 655-656
TL;DR: Two-step reactive ion etching process has been optimized to demonstrate small cross-section single-mode silicon waveguides as mentioned in this paper, which has helped to reduce the insertion loss of compact integrated photonic devices in SOI platform up to 3 dB.
Abstract: Two-step reactive ion etching process has been optimized to demonstrate small cross-section single-mode silicon waveguides This technique has helped to reduce the insertion loss of compact integrated photonic devices in SOI platform up to 3 dB
Citations
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Journal ArticleDOI
TL;DR: In this paper, a reactive ion etching chemistry has been optimized for trimming of rib waveguides and an empirical model has been developed to obtain the resulting waveguide geometries.
Abstract: Surface trimming of rib waveguides fabricated in 5-μm SOI substrate has been carried out successfully without any significant increase of propagation losses. A reactive ion etching chemistry has been optimized for trimming and an empirical model has been developed to obtain the resulting waveguide geometries. This technique has been used to demonstrate smaller footprint devices like multimode interference based power splitters and ring resonators after defining them photolithographically with relatively large cross-section rib waveguides. We have been also successful to fabricate 2D tapered spot-size converter useful for monolithic integration of waveguides with varying heights and widths. The taper length is again precisely controlled by photolithographic definition. Minimum insertion loss of such a spot-size converter integrated between waveguides with 3-μm height difference has been recorded to be ∼2 dB. It has been also shown that the overall fiber-to-chip coupling loss can be reduced by >3 dB by using such spot-size converters at the input/output side of the waveguides.

3 citations

References
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Journal ArticleDOI
TL;DR: In this article, mode-matching and beam-propagation methods are used to analyze single-mode operation of optical GeSi-Si and Si-SiO/sub 2/ semiconductor rib waveguides.
Abstract: Mode-matching and beam-propagation methods are used to analyze single-mode operation of optical GeSi-Si and Si-SiO/sub 2/ semiconductor rib waveguides. The waveguide dimensions that allow only the fundamental HE/sub 00/ or EH/sub 00/ mode to propagate have been determined. For both material systems, it is found that the rib can be several microns wide and several microns high, thus allowing efficient coupling to single-mode fibers. Numerical examples are given for monomode guiding group-IV materials, but the results apply to III-V rib waveguides. It is shown that single-mode rib guides with large cross sections are feasible as long as the waveguide is at least several millimeters long. >

696 citations


"Tapering and size reduction of sing..." refers background or methods in this paper

  • ...The design parameters W0, H0, and h0 of a single-mode LCRW structure are usually estimated by the well-known Soref's conditions [1]....

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  • ...There have been three types of single-mode waveguide structures investigated thoroughly in SOI platform: large cross-section rib waveguide (LCRW) [1], reduced cross-section rib waveguide (RCRW) [2] and photonic wire waveguide (PhWW) [3]....

    [...]

Journal ArticleDOI
TL;DR: A high-efficiency broadband grating coupler for coupling between silicon-on-insulator (SOI) waveguides and optical fibers and the size of the grooves is optimized numerically.
Abstract: We have designed a high-efficiency broadband grating coupler for coupling between silicon-on-insulator (SOI) waveguides and optical fibers. The grating is only 13 µm long and 12 µm wide, and the size of the grooves is optimized numerically. For TE polarization the coupling loss to single-mode fiber is below 1 dB over a 35-nm wavelength range when using SOI with a two-pair bottom reflector. The tolerances to fabrication errors are also calculated.

676 citations


"Tapering and size reduction of sing..." refers background in this paper

  • ...Conventionally, tapered waveguides [4] or grating couplers [5] are used to overcome this limitation....

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Journal ArticleDOI
TL;DR: In this article, two types of low-loss converters between different optical waveguides on silicon-on-insulator are demonstrated, and the fabrication of both structures is based on a simple two-step etch process with a relaxed mask alignment tolerance and no need for epitaxy.
Abstract: Two types of low-loss converters between different optical waveguides on silicon-on-insulator are demonstrated. A vertical taper between 9.4- and 3.8-/spl mu/m-thick single-moded rib waveguides gives an excess loss of 0.7/spl plusmn/0.2 dB with negligible polarization dependency. The second structure converts a 9.7-/spl mu/m-thick rib waveguide into an equally thick and highly multimoded strip waveguide with a negligible loss (<0.07 dB) for the fundamental mode. The fabrication of both structures is based on a simple two-step etch process with a relaxed mask alignment tolerance and no need for epitaxy.

56 citations

Journal ArticleDOI
TL;DR: In this article, a dispersion-free interleaver design has been proposed, fabricated, and characterized to separate alternate DWDM channels with 100 GHz spacings with a uniform inter-channel extinction of 18 dB.
Abstract: Integrated optical asymmetric Mach-Zehnder interferometer-based dense wavelength division multiplexing (DWDM) channel interleaver structures (2 × 2) have been theoretically studied using various single-mode waveguide geometries in silicon-on-insulator platform. Subsequently, a dispersion-free interleaver design has been proposed, fabricated, and characterized. It was designed to separate alternate DWDM channels with 100 GHz spacings. Some of the fabricated prototype devices have been fiber pigtailed and packaged in a suitably designed metal housing. The transmitted spectra (1520 nm <; λ <; 1600 nm) at each of the output ports reveal that alternate DWDM channel wavelengths are separated with a uniform inter-channel extinction of ~ 18 dB. Each of the channel passbands shows their 3-dB bandwidth of ~ 40 GHz.

17 citations


"Tapering and size reduction of sing..." refers background in this paper

  • ...Again, single-mode RCRW and PhWW structures can be designed by proper scaling of these three parameters [2]....

    [...]

  • ...There have been three types of single-mode waveguide structures investigated thoroughly in SOI platform: large cross-section rib waveguide (LCRW) [1], reduced cross-section rib waveguide (RCRW) [2] and photonic wire waveguide (PhWW) [3]....

    [...]

Proceedings ArticleDOI
08 Feb 2007
TL;DR: In this article, the authors have demonstrated various optical devices based on silicon photonic-wire waveguides, which include a directional coupler, a tunable optical add-drop multiplexer, and some ultra-compact 1 x N optical switches.
Abstract: Silicon photonic-wire waveguide is one of the most promising platforms in constructing compact optical devices, since the waveguide can be bent with a radius of less then several microns. Recently, we have demonstrated various optical devices based on silicon photonic-wire waveguides, which include a directional coupler, a tunable optical add-drop multiplexer, and some ultra-compact 1 x N optical switches. The optical coupling length of the directional coupler was just around 10 microns, due to its high coupling efficiency. The tunable optical add-drop multiplexer was constructed with Bragg grating waveguides. It was about 700-μm-long, and was controlled through thermo-optic effect. The maximum center-wavelength shift of the tunable optical add-drop multiplexer was 6.6 nm, which was obtained at a tuning power of 0.82 W. The 1 x N optical switches were Mach-Zehnder interferometer types and were also thermally controlled. The 1 x 2 switch was compact with a footprint of 85 x 30 μm 2 . Its maximum extinction ratio exceeded 30 dB. The switching power and switching time was about 90 mW and 100 μsec, respectively. The 1x4 optical switch was constructed based on the 1 x 2 switch. Its operation was successfully demonstrated. The 1 x 4 optical switch was believed to be the smallest switch in the world. A 1 x 8 optical switch was also demonstrated with its switching operations. Further, we are fabricating a compact packaged switch module with a size of 15 x 8 x 5 (height) mm 3 , which includes a 1 x 4 optical switch and the input and output fiber couplers assembly.

9 citations


"Tapering and size reduction of sing..." refers background in this paper

  • ...There have been three types of single-mode waveguide structures investigated thoroughly in SOI platform: large cross-section rib waveguide (LCRW) [1], reduced cross-section rib waveguide (RCRW) [2] and photonic wire waveguide (PhWW) [3]....

    [...]