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High-Q CMOS-integrated photonic crystal microcavity devices.

Mehta KK, Orcutt JS, Tehar-Zahav O, Sternberg Z, Bafrali R, Meade R, Ram RJ - Sci Rep (2014)

Bottom Line: Integrated optical resonators are necessary or beneficial in realizations of various functions in scaled photonic platforms, including filtering, modulation, and detection in classical communication systems, optical sensing, as well as addressing and control of solid state emitters for quantum technologies.Quasi-1D resonators in lateral p-i-n structures allow for resonant defect-state photodetection in all-silicon devices, exhibiting voltage-dependent quantum efficiencies in the range of a few 10 s of %, few-GHz bandwidths, and low dark currents, in devices with loaded Qs in the range of 4,300-9,300; one device, for example, exhibited a loaded Q of 4,300, 25% quantum efficiency (corresponding to a responsivity of 0.31 A/W), 3 GHz bandwidth, and 30 nA dark current at a reverse bias of 30 V.This work demonstrates the possibility for practical integration of PhC microresonators with active electro-optic capability into large-scale silicon photonic systems.

View Article: PubMed Central - PubMed

Affiliation: Department of Electrical Engineering & Computer Science and Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA, USA 02139.

ABSTRACT
Integrated optical resonators are necessary or beneficial in realizations of various functions in scaled photonic platforms, including filtering, modulation, and detection in classical communication systems, optical sensing, as well as addressing and control of solid state emitters for quantum technologies. Although photonic crystal (PhC) microresonators can be advantageous to the more commonly used microring devices due to the former's low mode volumes, fabrication of PhC cavities has typically relied on electron-beam lithography, which precludes integration with large-scale and reproducible CMOS fabrication. Here, we demonstrate wavelength-scale polycrystalline silicon (pSi) PhC microresonators with Qs up to 60,000 fabricated within a bulk CMOS process. Quasi-1D resonators in lateral p-i-n structures allow for resonant defect-state photodetection in all-silicon devices, exhibiting voltage-dependent quantum efficiencies in the range of a few 10 s of %, few-GHz bandwidths, and low dark currents, in devices with loaded Qs in the range of 4,300-9,300; one device, for example, exhibited a loaded Q of 4,300, 25% quantum efficiency (corresponding to a responsivity of 0.31 A/W), 3 GHz bandwidth, and 30 nA dark current at a reverse bias of 30 V. This work demonstrates the possibility for practical integration of PhC microresonators with active electro-optic capability into large-scale silicon photonic systems.

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(a) Optical micrograph of a single cavity device, with grating couplers and tapers for input/output light coupling. (b) SEM image of pSi in a fabricated PhC device, with FDTD-calculated mode profile overlaid. (c) and (d) Measured transmission spectra through cavities with resonant wavelengths λ0 ≈ 1512 (a = 320 nm, w = 450 nm) and λ0 ≈ 1549 nm (a = 330 nm, w = 470 nm), respectively. Curves and fits for cavities with 8, 12 and 18 pairs of mirror holes are shown for each (black, red and blue curves), with (e) peak resonant transmissions fit to theoretical predictions as function of total quality factor, allowing extraction of intrinsic Qs of 58,000 (black curve for λ0 = 1512 nm cavity) and 51,000 (red curve, λ0 = 1549 nm).
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f2: (a) Optical micrograph of a single cavity device, with grating couplers and tapers for input/output light coupling. (b) SEM image of pSi in a fabricated PhC device, with FDTD-calculated mode profile overlaid. (c) and (d) Measured transmission spectra through cavities with resonant wavelengths λ0 ≈ 1512 (a = 320 nm, w = 450 nm) and λ0 ≈ 1549 nm (a = 330 nm, w = 470 nm), respectively. Curves and fits for cavities with 8, 12 and 18 pairs of mirror holes are shown for each (black, red and blue curves), with (e) peak resonant transmissions fit to theoretical predictions as function of total quality factor, allowing extraction of intrinsic Qs of 58,000 (black curve for λ0 = 1512 nm cavity) and 51,000 (red curve, λ0 = 1549 nm).

Mentions: To allow efficient electrical contact to the resonator without introducing large optical loss, thin ≈ 50 nm-thick pSi “wings” were placed adjacent to the cavity. However, continuous slabs, in conjunction with the SiN liner layers, had effective indices large enough to couple to some Fourier components of the resonant mode, resulting in optical leakage, which could be reduced by patterning the wings with a 2D lattice of triangular low index holes; this had the effect also of reducing the resonant mode field's evanescent decay into the wings, allowing doped regions to be brought closer to the cavity (see Supplementary Information). This patterning was done with a lattice of r = 0.3a holes here. An SEM image of a resulting structure along with the FDTD-calculated resonant electric field profile is shown in Fig. 2(b). The intrinsic radiative Q of the contacted structure was calculated to be ≈ 300,000, and the mode volume 0.8(λ/n)3.


High-Q CMOS-integrated photonic crystal microcavity devices.

Mehta KK, Orcutt JS, Tehar-Zahav O, Sternberg Z, Bafrali R, Meade R, Ram RJ - Sci Rep (2014)

(a) Optical micrograph of a single cavity device, with grating couplers and tapers for input/output light coupling. (b) SEM image of pSi in a fabricated PhC device, with FDTD-calculated mode profile overlaid. (c) and (d) Measured transmission spectra through cavities with resonant wavelengths λ0 ≈ 1512 (a = 320 nm, w = 450 nm) and λ0 ≈ 1549 nm (a = 330 nm, w = 470 nm), respectively. Curves and fits for cavities with 8, 12 and 18 pairs of mirror holes are shown for each (black, red and blue curves), with (e) peak resonant transmissions fit to theoretical predictions as function of total quality factor, allowing extraction of intrinsic Qs of 58,000 (black curve for λ0 = 1512 nm cavity) and 51,000 (red curve, λ0 = 1549 nm).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3921634&req=5

f2: (a) Optical micrograph of a single cavity device, with grating couplers and tapers for input/output light coupling. (b) SEM image of pSi in a fabricated PhC device, with FDTD-calculated mode profile overlaid. (c) and (d) Measured transmission spectra through cavities with resonant wavelengths λ0 ≈ 1512 (a = 320 nm, w = 450 nm) and λ0 ≈ 1549 nm (a = 330 nm, w = 470 nm), respectively. Curves and fits for cavities with 8, 12 and 18 pairs of mirror holes are shown for each (black, red and blue curves), with (e) peak resonant transmissions fit to theoretical predictions as function of total quality factor, allowing extraction of intrinsic Qs of 58,000 (black curve for λ0 = 1512 nm cavity) and 51,000 (red curve, λ0 = 1549 nm).
Mentions: To allow efficient electrical contact to the resonator without introducing large optical loss, thin ≈ 50 nm-thick pSi “wings” were placed adjacent to the cavity. However, continuous slabs, in conjunction with the SiN liner layers, had effective indices large enough to couple to some Fourier components of the resonant mode, resulting in optical leakage, which could be reduced by patterning the wings with a 2D lattice of triangular low index holes; this had the effect also of reducing the resonant mode field's evanescent decay into the wings, allowing doped regions to be brought closer to the cavity (see Supplementary Information). This patterning was done with a lattice of r = 0.3a holes here. An SEM image of a resulting structure along with the FDTD-calculated resonant electric field profile is shown in Fig. 2(b). The intrinsic radiative Q of the contacted structure was calculated to be ≈ 300,000, and the mode volume 0.8(λ/n)3.

Bottom Line: Integrated optical resonators are necessary or beneficial in realizations of various functions in scaled photonic platforms, including filtering, modulation, and detection in classical communication systems, optical sensing, as well as addressing and control of solid state emitters for quantum technologies.Quasi-1D resonators in lateral p-i-n structures allow for resonant defect-state photodetection in all-silicon devices, exhibiting voltage-dependent quantum efficiencies in the range of a few 10 s of %, few-GHz bandwidths, and low dark currents, in devices with loaded Qs in the range of 4,300-9,300; one device, for example, exhibited a loaded Q of 4,300, 25% quantum efficiency (corresponding to a responsivity of 0.31 A/W), 3 GHz bandwidth, and 30 nA dark current at a reverse bias of 30 V.This work demonstrates the possibility for practical integration of PhC microresonators with active electro-optic capability into large-scale silicon photonic systems.

View Article: PubMed Central - PubMed

Affiliation: Department of Electrical Engineering & Computer Science and Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA, USA 02139.

ABSTRACT
Integrated optical resonators are necessary or beneficial in realizations of various functions in scaled photonic platforms, including filtering, modulation, and detection in classical communication systems, optical sensing, as well as addressing and control of solid state emitters for quantum technologies. Although photonic crystal (PhC) microresonators can be advantageous to the more commonly used microring devices due to the former's low mode volumes, fabrication of PhC cavities has typically relied on electron-beam lithography, which precludes integration with large-scale and reproducible CMOS fabrication. Here, we demonstrate wavelength-scale polycrystalline silicon (pSi) PhC microresonators with Qs up to 60,000 fabricated within a bulk CMOS process. Quasi-1D resonators in lateral p-i-n structures allow for resonant defect-state photodetection in all-silicon devices, exhibiting voltage-dependent quantum efficiencies in the range of a few 10 s of %, few-GHz bandwidths, and low dark currents, in devices with loaded Qs in the range of 4,300-9,300; one device, for example, exhibited a loaded Q of 4,300, 25% quantum efficiency (corresponding to a responsivity of 0.31 A/W), 3 GHz bandwidth, and 30 nA dark current at a reverse bias of 30 V. This work demonstrates the possibility for practical integration of PhC microresonators with active electro-optic capability into large-scale silicon photonic systems.

No MeSH data available.


Related in: MedlinePlus