Fiscal Year 2012
Optical diodes (optical isolators) are very important devices for fabricating optical circuits by combining optical elements. Optical diodes that can be integrated into optical circuits must be fabricated on Si substrates using the COMS process and have a small device size. Against this background, this paper describes an optical diode based on a micro ring resonator that can be fabricated on Si using a CMOS process.
In this Journal club, we will focus on the principle of operation of the photodiodes reported in this paper.
A photon source that can stably produce a single photon is necessary for quantum information processing. Recently, the luminescence from the NV center of diamond has attracted attention as a stable single-photon source at room temperature. Furthermore, it has been found that single photon generation can be enhanced by combining the luminescence from the NV center with plasmons.
In this paper, we report the fabrication of a more efficient single-photon device by applying a silver coating to a cylindrical structure containing NV centers on a diamond substrate. The top-down approach enables mass production of single-photon sources, and this research is a stepping stone for large-scale experiments using single-photon sources in the future.
Key Word; nitrogen-vacancy center, plasmon, single photon, quamtum optics
The ultimate goal in controlling light is to use single photons. However, the nonlinear optical effects of single photons are very small and difficult to achieve. Although this type of research has been achieved in Cavity QED, there is still no practical and robust way to achieve this goal.
The paper presented here proposes a single-photon optical transistor on a nanowire with a size below the diffraction limit by using the surface plasmon property. The content is explained entirely by simulation, and we plan to further develop the system by combining it with the conventional Cavity QED system.
Key Word; surface plasmon, single-photon, quamtum optics
It is widely known that "the speed of light cannot be exceeded," but this is true for a single substance in a vacuum. Using the concept of group velocity, we can derive the value of the speed faster than the speed of light. In this paper, we have created a light pulse that propagates faster than the speed of light, called "fast light," and conducted an experiment to transmit digital information "1 or 0" using this pulse. The experimental results compare the transmission of information at the speed of light with that at "fast light," proving experimentally the problem that has been discussed since the 1960s that the speed of light cannot be exceeded even in "information transmission.
In this Journal club, I would like to talk about the concept of "fast light" and experimental methods.
There are photonic crystals that excel in their ability to confine and integrate light in micro optical resonators. However, the incompatibility of these resonators with optical fibers makes it difficult to connect them to other devices. In this paper, we introduce a device that integrates a photonic crystal and an optical fiber by directly bonding the photonic crystal to the optical fiber using epoxy resin. The content mainly consists of four optical measurements using this device, and the fourth and last optical system is all integrated by optical fibers.
The Journal Club will focus on the fabrication and optical measurements of the devices, as well as the future development of these devices.
The technique of making objects invisible, known as "cloaking," has attracted much attention in recent years. The use of structures with sizes smaller than a wavelength makes it possible to freely design the refractive index distribution, which in turn makes it possible to freely manipulate the propagation path of light rays. In this paper, we succeeded in experimentally verifying cloaking in the optical domain using microstructures on silicon.
The Journal Club will focus on the progress of cloning technology and its principles.
Realization of Atomic Traps on Tapered Optical Fiber Surfaces
Atomic traps using lasers are widely used. Atomic traps are essential for observing and utilizing quantum effects. Atomic traps using optical fibers have been difficult to connect because they are hollow inside and atoms are placed in them. In this paper, we succeeded in trapping cesium atoms in an evanescent field using a tapered optical fiber. By adjusting the wavelength and intensity of the laser input to the tapered optical fiber, a potential trap was generated near the fiber surface, in which approximately 2000 cesium atoms were trapped.
In the Journal Club, we plan to explain the optical trapping technique in detail.
Quantum coherent coupling between mechanical oscillator and optical resonator modes Recently, attempts have been made to couple light and mechanical vibration modes by using micro optical resonators that confine light in a very small space. This is a coherent coupling in which the radiation pressure of light is used to excite mechanical vibration, which in turn excites light. While coherent coupling between microwaves and mechanical vibrations has only been realized in the past, in this paper we aim at coherent coupling between light and mechanical vibrations at the quantum level. Experimental results show that excitation with weak classical light pulses can induce energy exchange between light and micromechanical oscillators at the quantum level, which averages less than one quantum in the time domain.
In this Journal club, I would like to talk about EIT and OMIT, with emphasis on anit-crossing.
Quantum circuits based on spatial optics have long been considered problematic due to the instability of interference and the complexity of adjustment. In this study, we fabricated a CNOT gate, one of the basic gates of a quantum computer, on a Si chip using an existing semiconductor process. This research is expected to contribute not only to the stabilization of photon interference but also to the miniaturization and integration of quantum circuits.
In this Journal club, we plan to focus on the fundamentals of CNOT gate using photons, such as the historical background of the realization of CNOT gate and the operating principle of the gate.
Quantum coherent coupling between mechanical oscillator and optical resonator modes
Recently, attempts have been made to couple light and mechanical vibration modes using micro optical resonators that confine light in a very small space. This is a coherent coupling in which the radiation pressure of light is used to excite mechanical vibration, which in turn excites light. While coherent coupling between microwaves and mechanical vibrations has only been realized in the past, in this paper we aim at coherent coupling between light and mechanical vibrations at the quantum level. Experimental results show that excitation with weak classical light pulses can induce energy exchange between light and micro-mechanical oscillators at the level of an average of less than one quantum in the time domain.
In this Journal club, we would like to explain the basic concepts of this field called opto-mechanics, what has been achieved in this experiment, and future prospects.
This paper presents a paper on Pressure Sensitive Paint (PSP), a recently developed technology for measuring pressure on aircraft surfaces, mainly used in wind tunnel experiments. Conventional surface measurement involves making numerous holes (pressure holes) in the surface of a model and connecting pipes extending from the holes. It also has the advantage of surface measurement instead of the conventional point measurement. In this paper, we report on the results obtained during a flight from Sendai Airport to Fukushima after spraying PSP on the wings of a Beechcraft 65 airplane. I decided to present this paper because I am currently participating in an internship program at the Japan Aerospace Exploration Agency (JAXA). Therefore, I would like to talk a little about JAXA as well.
In optical circuits using surface plasmon polaritons (SPPs), it has been difficult to simultaneously increase the localization and detection efficiency of SPPs. In this study, we proposed a new SPP detection method based on near-field coupling between plasmons and nano-wire FETs. The detection efficiency of 10% is high despite its nano-size, and the signal can also be amplified for detection. In this presentation, we will focus on the principle and the advantage of using plasmons.
In this paper, we present the achievement of a high power of 110 K, which is equivalent to that of a single-crystal YAG laser, using a ceramic YAG. In principle, ceramics cannot compete with single-crystal YAG, but this result has been achieved due to the fact that the single-crystal fabrication method has not been fully established and due to improvements in the ceramic fabrication process. This lecture will focus on the performance of ceramic YAG and single-crystal YAG lasers and devices, as well as a comparison of their production aspects.
Due to the uncertainty principle, it is in principle impossible to observe the trajectory of a single photon passing through a double slit. However, in this paper, we have succeeded in observing the average trajectory of a single photon using a method called "weak measurement". In this presentation, the principle and experimental method used will be explained with special emphasis.
We will periodically announce the event.
Anyone can register.
This is an open lecture series held in Tanabe Photonic Structures Laboratory. Students who are graduate students or above will survey papers related to optics and related technologies such as photonics, materials, bioscience, etc., and explain them in an easy-to-understand manner.
Attendance is free, regardless of whether you are inside or outside of the university. The seminar will be held periodically, so if you are interested in any of the topics, please feel free to attend. No notice is required to attend, but we will prepare materials if you contact us in advance.
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