This paper reviews the work on cavity quantum electrodynamics of free atoms. In recent years, cavity experiments have also been conducted on a variety of solid-state systems resulting in many interesting applications, of which microlasers, photon bandgap structures and quantum dot structures in cavities are outstanding examples. Although these phenomena and systems are very interesting, discussion is limited here to free atoms and mostly single atoms because these systems exhibit clean quantum phenomena and are not disturbed by a variety of other effects. At the centre of our review is the work on the one-atom maser, but we also give a survey of the entire field, using free atoms in order to show the large variety of problems dealt with. The cavity interaction can be separated into two main regimes: the weak coupling in cavity or cavity-like structures with low quality factors Q and the strong coupling when high-Q cavities are involved. The weak coupling leads to modification of spontaneous transitions and level shifts, whereas the strong coupling enables one to observe a periodic exchange of photons between atoms and the radiation field. In this case, atoms and photons are entangled, this being the basis for a variety of phenomena observed, some of them leading to interesting applications in quantum information processing. The cavity experiments with free atoms reached a new domain with the advent of experiments in the visible spectral region. A review on recent achievements in this area is also given.

https://iopscience.iop.org/article/10.1088/0034-4885/69/5/R02/pdf

Cavity quantum electrodynamics

The modification and control of exciton–photon interactions in semiconductors is of both fundamental1,2,3,4 and practical interest, being of direct relevance to the design of improved light-emitting diodes, photodetectors and lasers5,6,7. In a semiconductor microcavity, the confined electromagnetic field modifies the optical transitions of the material. Two distinct types of interaction are possible: weak and strong coupling1,2,3,4. In the former perturbative regime, the spectral and spatial distribution of the emission is modified but exciton dynamics are little altered. In the latter case, however, mixing of exciton and photon states occurs leading to strongly modified dynamics. Both types of effect have been observed in planar microcavity structures in inorganic semiconductor quantum wells and bulk layers1,2,3,4,5,6,7,8. But organic semiconductor microcavities have been studied only in the weak-coupling regime9,10,11,12,13,14,15,16,17,18. Here we report an organic semiconductor microcavity that operates in the strong-coupling regime. We see characteristic mixing of the exciton and photon modes (anti-crossing), and a room-temperature vacuum Rabi splitting (an indicator of interaction strength) that is an order of magnitude larger than the previously reported highest values for inorganic semiconductors. Our results may lead to new structures and device concepts incorporating hybrid states of organic and inorganic excitons19, and suggest that polariton lasing20,21,22 may be possible.

Strong exciton–photon coupling in an organic semiconductor microcavity

We review the family of optoelectronic devices whose performance is enhanced by placing the active device structure inside a Fabry‐Perot resonantmicrocavity. Such resonantcavity enhanced (RCE) devices benefit from the wavelength selectivity and the large increase of the resonant optical field introduced by the cavity. The increased optical field allows RCE photodetector structures to be thinner and therefore faster, while simultaneously increasing the quantum efficiency at the resonant wavelengths. Off‐resonance wavelengths are rejected by the cavity making RCE photodetectors promising for low crosstalk wavelength division multiplexing(WDM) applications. RCE optical modulators require fewer quantum wells so are capable of reduced voltage operation. The spontaneous emission spectrum of RCE light emitting diodes(LED) is drastically altered, improving the spectral purity and directivity. RCE devices are also highly suitable for integrated detectors and emitters with applications as in optical logic and in communication networks. This review attempts an encyclopedic overview of RCE photonicdevices and systems. Considerable attention is devoted to the theoretical formulation and calculation of important RCE device parameters. Materials criteria are outlined and the suitability of common heteroepitaxial systems for RCE devices is examined. Arguments for the improved bandwidth in RCE detectors are presented intuitively, and results from advanced numerical simulations confirming the simple model are provided. An overview of experimental results on discrete RCE photodiodes, phototransistors, modulators, and LEDs is given. Work aimed at integrated RCE devices,optical logic and WDM systems is also covered. We conclude by speculating what remains to be accomplished to implement a practical RCE WDM system.

Resonant cavity enhanced photonic devices

Quantum well excitons in semiconductor microcavities : unified treatment of weak and strong coupling regimes

The semiconductor laser is the cornerstone of modern technology and science. It is being incorporated into an increasing number of applications, ranging from element detection through telecommunications to entertainment. This wide spread of applications is due to the spectral range of the semiconductor laser, which extends from the blue to the far IR, and the attainable output power of several tens of watts. Since light-emitting organic materials are also semiconductors, it is an obvious step to try to introduce their inherent advantages into the laser field. While the direct benefits of incorporating organic lasers into applications are very stimulating, the process of making a laser can also teach us much about its constituent material properties. Since organic materials are constantly evolving, the making of lasers incorporates valuable contributions from a variety of disciplines, extending from organic chemistry through physics to device engineering. With this in mind, this review is also intended for those not necessarily familiar with lasers. The rest of the article is organized as follows: A start is made by looking at the definition of a laser and discussing the issues associated with determining its threshold. A historical overview is then given, spanning from the 1960s to the 1990s. Section 5.1 reviews the recent progress in optically pumped lasers and Section 5.2 is devoted to electrical properties of light-emitting diodes (LEDs), which may affect the performance of future electrically pumped lasers. The figures used in this work are largely taken from data acquired by the author and his colleagues. However, the rapid progress in this field is due to a large number of research groups, as the text will show.

Lasers Based on Semiconducting Organic Materials

Line Broadening of Semiconductor Lasers (C. Henry). Modulation and Noise Spectra of Complicated Laser Structures (O. Nilsson, et al.). Frequency Tunability, Frequency Modulation, and Spectral Linewidth of Complicated Structure Lasers (Y. Yoshikuni). Spectroscopy by Semiconductor Lasers (M. Ohtsu & K. Nakagawa). Coherent Detection Using Semiconductor Lasers: System Design Concepts and Experiments (T. Hodgkinson). Traveling--Wave Semiconductor Laser Amplifiers (T. Saitoh & T. Mukai). Semiconductor Laser Amplifiers in High--Bit--Rate and Wavelength--Division--Multiplexed Optical Communication Systems (R. Jopson & T. Darcie). Injection--Locked Semiconductor Laser Amplifiers (S. Kobayashi). Photon Statistics and Mode Partition Noise of Semiconductor Lasers (P. Liu). Squeezed--State Generation by Semiconductor Lasers (Y. Yamamoto, et al.). Generation of Photon--Number--Squeezed Light by Semiconductor Incoherent Light Sources (M. Teich, et al.). Controlled Spontaneous Emission in Microcavity Semiconductor Lasers (Y. Yamamoto, et al.). Index.

喜久山本

Papers

Coherence, amplification, and quantum effects in semiconductor lasers

喜久 山本

Papers

Coherence, amplification, and quantum effects in semiconductor lasers

喜久山本