For the first time, Japanese researchers have demonstrated that photons can be manipulated on the surface of 3D photonic crystals. This achievement has helped to develop advanced photonic integrated circuits, highly sensitive sensors and innovative photonic nanodevices.
Photonic crystals can be used as a nanostructured material with periodic variations in certain parameters (usually the dielectric constant of a material) that produce a photon "bandgap" that affects how photons are Material spread. This so-called photonic band structure is very similar to the periodic potential in semiconductors. As early as half a century ago, physicists knew that electrons in crystals (such as semiconductors) were subjected to lattice periodicity. Potential scattering, part of the band will form an energy gap due to destructive interference, resulting in a dispersion relationship of electron dispersion (distribution), which is known as electronic band structures.
However, it was not until 1987 that E. Yablonovitch and S. John pointed out that similar phenomena exist in the photosystem: in a three-dimensional dielectric material in which the dielectric constant is periodically arranged, after the electromagnetic wave is scattered by the dielectric function, The electromagnetic wave intensity of some bands is exponentially attenuated due to destructive interference and cannot be transmitted in the system. It is equivalent to forming an energy gap in the spectrum, so the dispersion relationship also has a band structure. This is called photonic band structure (photonicband). Structures). A dielectric substance having a photonic band structure is called a photonic band-gap system (PBG system for short), or simply photonic crystals.
Similar to the case of semiconductors, the impurity state of photonic crystals also mostly falls within the energy gap, which makes the energy gap of the original "forbidden zone" appear "first-line life". The energy gap gives humans the ability to limit electromagnetic waves, and the first-line life provided by impurities gives us the possibility to guide electromagnetic waves, which is of great value in optoelectronics. Therefore, in the field of photonic crystals, impurity states are an important research topic.
For an impurity state, since the impurity is surrounded by a "forbidden zone" formed by photonic crystals, the electromagnetic wave can only be confined to the vicinity of the impurity in space distribution, so a point defect is equivalent to a microcavity (micro-cavity). ). Electromagnetic waves can travel along these defects, which is equivalent to a waveguide, so scientists can control and manipulate the photon flow by introducing impurities to form "defects."
So far, the only thing scientists can do is to control photons by introducing defects inside the crystal, but Susumu Noda and Kenji Ishizaki of Kyoto University have found that they can also manipulate photons on the surface of 3D photonic crystals. This effect will open a new door for a range of new applications, such as manipulating photons through photonic crystals on photonic integrated circuits.
The discovery of Noda and Ishizaki also proved for the first time that 3D photonic crystals have surface states, and photons can be confined to and propagate in these surface states. Next, the researchers demonstrated that photons can be localized to specific surface points (by forming a surface modemodegap and introducing surface defect structures). To their surprise, they have a quality(Q) parameter of up to 9000, which is by far the highest value achieved by 3D photonic crystal nanotechnology. The Q value mainly indicates the limit at which photons are accommodated in the nanostructure, and the higher the Q value, the better.
Since the surface of 3D photonic crystals does not absorb light, this technology can be used to create new sensors. Other emerging applications include advanced photonic integrated circuits and innovative nanodevices, such as LEDs and solar cells. performance.
The number of photonic crystal stack layers developed by Noda and Ishizaki is 8 layers, and researchers plan to add more quantities, which can better limit photons and reduce the number of photons leaking from the bottom layer.
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Defect structure and photon limitation
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3D photonic crystal surface
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3D photonic crystal surface electric field distribution diagram
Photonic crystals can be used as a nanostructured material with periodic variations in certain parameters (usually the dielectric constant of a material) that produce a photon "bandgap" that affects how photons are Material spread. This so-called photonic band structure is very similar to the periodic potential in semiconductors. As early as half a century ago, physicists knew that electrons in crystals (such as semiconductors) were subjected to lattice periodicity. Potential scattering, part of the band will form an energy gap due to destructive interference, resulting in a dispersion relationship of electron dispersion (distribution), which is known as electronic band structures.
However, it was not until 1987 that E. Yablonovitch and S. John pointed out that similar phenomena exist in the photosystem: in a three-dimensional dielectric material in which the dielectric constant is periodically arranged, after the electromagnetic wave is scattered by the dielectric function, The electromagnetic wave intensity of some bands is exponentially attenuated due to destructive interference and cannot be transmitted in the system. It is equivalent to forming an energy gap in the spectrum, so the dispersion relationship also has a band structure. This is called photonic band structure (photonicband). Structures). A dielectric substance having a photonic band structure is called a photonic band-gap system (PBG system for short), or simply photonic crystals.
Similar to the case of semiconductors, the impurity state of photonic crystals also mostly falls within the energy gap, which makes the energy gap of the original "forbidden zone" appear "first-line life". The energy gap gives humans the ability to limit electromagnetic waves, and the first-line life provided by impurities gives us the possibility to guide electromagnetic waves, which is of great value in optoelectronics. Therefore, in the field of photonic crystals, impurity states are an important research topic.
For an impurity state, since the impurity is surrounded by a "forbidden zone" formed by photonic crystals, the electromagnetic wave can only be confined to the vicinity of the impurity in space distribution, so a point defect is equivalent to a microcavity (micro-cavity). ). Electromagnetic waves can travel along these defects, which is equivalent to a waveguide, so scientists can control and manipulate the photon flow by introducing impurities to form "defects."
So far, the only thing scientists can do is to control photons by introducing defects inside the crystal, but Susumu Noda and Kenji Ishizaki of Kyoto University have found that they can also manipulate photons on the surface of 3D photonic crystals. This effect will open a new door for a range of new applications, such as manipulating photons through photonic crystals on photonic integrated circuits.
The discovery of Noda and Ishizaki also proved for the first time that 3D photonic crystals have surface states, and photons can be confined to and propagate in these surface states. Next, the researchers demonstrated that photons can be localized to specific surface points (by forming a surface modemodegap and introducing surface defect structures). To their surprise, they have a quality(Q) parameter of up to 9000, which is by far the highest value achieved by 3D photonic crystal nanotechnology. The Q value mainly indicates the limit at which photons are accommodated in the nanostructure, and the higher the Q value, the better.
Since the surface of 3D photonic crystals does not absorb light, this technology can be used to create new sensors. Other emerging applications include advanced photonic integrated circuits and innovative nanodevices, such as LEDs and solar cells. performance.
The number of photonic crystal stack layers developed by Noda and Ishizaki is 8 layers, and researchers plan to add more quantities, which can better limit photons and reduce the number of photons leaking from the bottom layer.
Defect structure and photon limitation
3D photonic crystal surface
3D photonic crystal surface electric field distribution diagram
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