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H1 photonic crystal nanocavities with a short sub-wavelength air-slot that can concentrate an electric field to one antinode with V<0.025(λ/n)3 experimentally exhibited a Q factor over 2×105 and a Q/V reaching 107.
We demonstrate a photonic-crystal photodetector under a forward bias voltage maintaining a 0.88-A/W responsivity and a 40-Gbit/s bitrate. This will allow an ultralow-energy receiver with high-impedance termination that requires neither amplifiers nor a bias circuit.
Generating correlated photons is an essential technology for photonic quantum information experiments. Increasing the generation efficiency of photon pairs via the enhancement of material nonlinearity is important for various applications including a near-on-demand single photon source based on multiplexed photon pair sources [1]. In this regard, photonic crystal nanocavities are attractive nonlinear...
Short distance optical communication is required to reduce power consumption of ICT systems and continuously improve performance of datacentres and HPCs [1]. Reduced energy consumption and increased bandwidth density [2-3] are required to develop optical interconnects between chips and on chips. Therefore, lasers and detectors with ultra-low operating energy have to be connected by Si nanowire waveguides...
Straight and curved waveguides in 2D photonic crystals with wide transmission bands were realized using coupled high-Q L2 nanocavities. A channel drop filter was created by combining two coupled curved nanocavities and an H0 nanocavity.
A plasmonic waveguide with a deep-subwavelength Si core is integrated with a Si photonic waveguide. By utilizing horizontal Al-Si-Al structure, we obtained a 4-dB/μm propagation loss with a 60 × 60 nm2 surface-oxidized Si core.
Performance of slow-light coupled-resonator optical waveguides (CROW) in a photonic crystal was analysed, and found to be limited by disorder-induced localisation. Localised modes were directly measured through out-of-plane loss.
We propose a parity-time symmetric coupled resonator waveguide based on buried heterostructure photonic crystal nanocavities. We show theoretically the potential to greatly tune its group velocity using the parity-time phase transition for the first time.
A photonic-crystal photodetector having a <1-fF junction capacitance, 1-A/W responsivity, and 40-Gbit/s eye opening was demonstrated. Its resistor-loaded configuration unveiled a light-to-voltage conversion with a kV/W efficiency without amplifiers, promising for an fJ/bit-energy on-chip receiver.
We have numerically simulated graphene-loaded silicon photonic crystal waveguides. We found that it is possible to create a nanocavity mode induced by graphene, and Fermi energy modulation of graphene enables us to control cavity formation.
Integrated optical circuits with nanophotonic devices have attracted significant attention due to its low power dissipation and light-speed operation. With light interference and resonance phenomena, the nanophotonic device works as a voltage-controlled optical pass-gate like a pass-transistor. This paper first introduces a concept of the optical pass-gate logic, and then proposes a parallel adder...
We present our latest research results about ultralow power integrated nanophotonic devices based on photonic crystals and some more nanophotonics. We will also discuss the possibility to employ these integrated nanophotonics for putting optical computing technologies into a processor chip.
Ultrasmall photonic-crystal photodetector-modulator integration provides a highly efficient alloptical functionality for high-bit-rate optical signals thanks to the high RC bandwidth. Wavelength conversion for 10-Gb/s optical signals was confirmed in a simulation and a preliminary experiment.
Enhanced coupling in slanted L3 nanocavity array expanded bandwidth to 4 THz at telecom wavelength. High-Q tuned L3 nanocavity realized 1,000 coupled cavities with acceptable propagation loss and delay-bandwidth product over 100.
Systematic multi-hole tuning of H0 nanocavity with theoretical Q of ∼107 is reported that outperforms L3 and other a-few-missing-hole nanocavities over a wide slab-thickness range. Experimental Q of ∼106 is achieved.
We achieved three-dimensional mode conversion between a Si-wire waveguide and a deep sub-λ plasmonic slot waveguide (60 χ 50 nm2) for the first time. The coupling loss was only about 2 dB.
Ultrasmall InGaAsP optical modulators were realized using a photonic crystal waveguide/nanocavity with a small-capacitance p-i-n junction and the Franz-Keldysh effect. Eye patterns reaching 56 Gb/s and a record-low charging energy of <100 aJ/bit were evaluated.
1.7-μm-long InGaAs photonic crystal photodetectors connected to a load resistor were demonstrated towards realizing ultralow-power photoreceivers without electrical amplifiers. A high light-to-voltage conversion efficiency of 4 kV/W was confirmed with electro-optic probing technique.
We evaluated high-speed behaviour of electrically driven photonic crystal lasers by direct modulations and found that they had 17.8-GHz 3-dB bandwidth. A 25-Gbit/s eye diagram was also demonstrated with a bias current as low as 150 μA.
We discuss why large-scale integration of nano-photonics is needed in future ICT, and describe our on-going research of integrated nanophotonics based on photonic crystals.
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