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CMOS compatible high-Q photonic crystal nanocavity fabricated with photolithography on silicon photonic platform.

Ooka Y, Tetsumoto T, Fushimi A, Yoshiki W, Tanabe T - Sci Rep (2015)

Bottom Line: Here we show that a 2D-PhC-NC fabricated with deep-UV photolithography on a silica-clad silicon-on-insulator (SOI) structure will exhibit a high-Q of 2.2 × 10(5) with a mode-volume of ~ 1.7(λ/n)(3).This is the highest Q demonstrated with photolithography.We also show that this device exhibits an efficient thermal diffusion and enables high-speed switching.

View Article: PubMed Central - PubMed

Affiliation: Department of Electronics and Electrical Engineering, Faculty of Science and Technology, Keio University, 3-14-1, Hiyoshi, Kohoku-ku, Yokohama 223-8522, Japan.

ABSTRACT
Progress on the fabrication of ultrahigh-Q photonic-crystal nanocavities (PhC-NCs) has revealed the prospect for new applications including silicon Raman lasers that require a strong confinement of light. Among various PhC-NCs, the highest Q has been recorded with silicon. On the other hand, microcavity is one of the basic building blocks in silicon photonics. However, the fusion between PhC-NCs and silicon photonics has yet to be exploited, since PhC-NCs are usually fabricated with electron-beam lithography and require an air-bridge structure. Here we show that a 2D-PhC-NC fabricated with deep-UV photolithography on a silica-clad silicon-on-insulator (SOI) structure will exhibit a high-Q of 2.2 × 10(5) with a mode-volume of ~ 1.7(λ/n)(3). This is the highest Q demonstrated with photolithography. We also show that this device exhibits an efficient thermal diffusion and enables high-speed switching. The demonstration of the photolithographic fabrication of high-Q silica-clad PhC-NCs will open possibility for mass-manufacturing and boost the fusion between silicon photonics and CMOS devices.

No MeSH data available.


Related in: MedlinePlus

Nonlinear measurement.(a) Transmission spectra of the width-modulated cavity (Q = 2.1 × 105) at different CW input powers Pin (shown in the graph). The centre wavelength shift is caused by the thermo optic effect, where the bistable threshold is at 19 μW. (b) Schematic illustration of the switching experiment. ATT: attenuator, DSO: digital sampling oscilloscope (20-GHz bandwidth), PD: photodiode (40-GHz bandwidth). BPF: band-pass filter. (c) All-optical switching experiment. Transmittance waveform of the signal light when the device is pumped with a picosecond pulse laser that is above the mode gap of the barrier line defects. The modulation is due to the carrier plasma dispersion effect caused by the excitation of the two-photon absorption carriers. The carrier lifetime is 0.12 ns.
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f3: Nonlinear measurement.(a) Transmission spectra of the width-modulated cavity (Q = 2.1 × 105) at different CW input powers Pin (shown in the graph). The centre wavelength shift is caused by the thermo optic effect, where the bistable threshold is at 19 μW. (b) Schematic illustration of the switching experiment. ATT: attenuator, DSO: digital sampling oscilloscope (20-GHz bandwidth), PD: photodiode (40-GHz bandwidth). BPF: band-pass filter. (c) All-optical switching experiment. Transmittance waveform of the signal light when the device is pumped with a picosecond pulse laser that is above the mode gap of the barrier line defects. The modulation is due to the carrier plasma dispersion effect caused by the excitation of the two-photon absorption carriers. The carrier lifetime is 0.12 ns.

Mentions: Figure 3a shows the output spectrum from the nanocavity which has Q of 2.1 × 105 at different input powers. The laser is swept from a short to a long wavelength, and we observe an asymmetric transmittance spectrum resulting from the TO bistability. The threshold power is 19 μW (intra-cavity power), which indicates that a 2D-PhC structure suffers much less from the TO effect than an 1D nanobeam cavity. Indeed the threshold value for an 1D nanobeam cavity was 1 μW when the Q is almost the same13. In addition, we measured the TO effect of an air-bridge sample to investigate the thermal diffusion through the SiO2 clad. When the SiO2 clad is removed, the threshold power decreased at 4.5 μW (intra cavity power) for a cavity with a Q of 2.3 × 105. It indicates that the surrounding SiO2 clad also contribute to a smaller TO effect. The small TO effect is usually preferred in photonic devices.


CMOS compatible high-Q photonic crystal nanocavity fabricated with photolithography on silicon photonic platform.

Ooka Y, Tetsumoto T, Fushimi A, Yoshiki W, Tanabe T - Sci Rep (2015)

Nonlinear measurement.(a) Transmission spectra of the width-modulated cavity (Q = 2.1 × 105) at different CW input powers Pin (shown in the graph). The centre wavelength shift is caused by the thermo optic effect, where the bistable threshold is at 19 μW. (b) Schematic illustration of the switching experiment. ATT: attenuator, DSO: digital sampling oscilloscope (20-GHz bandwidth), PD: photodiode (40-GHz bandwidth). BPF: band-pass filter. (c) All-optical switching experiment. Transmittance waveform of the signal light when the device is pumped with a picosecond pulse laser that is above the mode gap of the barrier line defects. The modulation is due to the carrier plasma dispersion effect caused by the excitation of the two-photon absorption carriers. The carrier lifetime is 0.12 ns.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4471896&req=5

f3: Nonlinear measurement.(a) Transmission spectra of the width-modulated cavity (Q = 2.1 × 105) at different CW input powers Pin (shown in the graph). The centre wavelength shift is caused by the thermo optic effect, where the bistable threshold is at 19 μW. (b) Schematic illustration of the switching experiment. ATT: attenuator, DSO: digital sampling oscilloscope (20-GHz bandwidth), PD: photodiode (40-GHz bandwidth). BPF: band-pass filter. (c) All-optical switching experiment. Transmittance waveform of the signal light when the device is pumped with a picosecond pulse laser that is above the mode gap of the barrier line defects. The modulation is due to the carrier plasma dispersion effect caused by the excitation of the two-photon absorption carriers. The carrier lifetime is 0.12 ns.
Mentions: Figure 3a shows the output spectrum from the nanocavity which has Q of 2.1 × 105 at different input powers. The laser is swept from a short to a long wavelength, and we observe an asymmetric transmittance spectrum resulting from the TO bistability. The threshold power is 19 μW (intra-cavity power), which indicates that a 2D-PhC structure suffers much less from the TO effect than an 1D nanobeam cavity. Indeed the threshold value for an 1D nanobeam cavity was 1 μW when the Q is almost the same13. In addition, we measured the TO effect of an air-bridge sample to investigate the thermal diffusion through the SiO2 clad. When the SiO2 clad is removed, the threshold power decreased at 4.5 μW (intra cavity power) for a cavity with a Q of 2.3 × 105. It indicates that the surrounding SiO2 clad also contribute to a smaller TO effect. The small TO effect is usually preferred in photonic devices.

Bottom Line: Here we show that a 2D-PhC-NC fabricated with deep-UV photolithography on a silica-clad silicon-on-insulator (SOI) structure will exhibit a high-Q of 2.2 × 10(5) with a mode-volume of ~ 1.7(λ/n)(3).This is the highest Q demonstrated with photolithography.We also show that this device exhibits an efficient thermal diffusion and enables high-speed switching.

View Article: PubMed Central - PubMed

Affiliation: Department of Electronics and Electrical Engineering, Faculty of Science and Technology, Keio University, 3-14-1, Hiyoshi, Kohoku-ku, Yokohama 223-8522, Japan.

ABSTRACT
Progress on the fabrication of ultrahigh-Q photonic-crystal nanocavities (PhC-NCs) has revealed the prospect for new applications including silicon Raman lasers that require a strong confinement of light. Among various PhC-NCs, the highest Q has been recorded with silicon. On the other hand, microcavity is one of the basic building blocks in silicon photonics. However, the fusion between PhC-NCs and silicon photonics has yet to be exploited, since PhC-NCs are usually fabricated with electron-beam lithography and require an air-bridge structure. Here we show that a 2D-PhC-NC fabricated with deep-UV photolithography on a silica-clad silicon-on-insulator (SOI) structure will exhibit a high-Q of 2.2 × 10(5) with a mode-volume of ~ 1.7(λ/n)(3). This is the highest Q demonstrated with photolithography. We also show that this device exhibits an efficient thermal diffusion and enables high-speed switching. The demonstration of the photolithographic fabrication of high-Q silica-clad PhC-NCs will open possibility for mass-manufacturing and boost the fusion between silicon photonics and CMOS devices.

No MeSH data available.


Related in: MedlinePlus