On the other hand, triangular lattice holes Fig. The cancellation effect at the center of the beam in Fig. In this case, the polarization is also different , being linear. Introducing such a nonsymmetrical effect is a key factor in achieving high optical output power by enabling a greater optical extraction efficiency in the perpendicular direction as described in the next section. Note that in the next section, a significantly asymmetric structure in the form of right-isoscelestriangle- shaped air holes was employed for much higher power operation.
Fig 3. Near-field pattern with lasing spectra at various points of the device. Electromagnetic field distribution in various photonic crystal lasers. The phase in each region was shifted by across the boundary where the phase shift was introduced. In the previous section, the photonic crystal was embedded in the device by a wafer-bonding technique, where bonded interface may contain many defect states which absorb the lasing light and make it difficult to realize high power operation.
To avoid such degradation of performance, we changed the method to introduce the photonic crystal into the device from a wafer bonding to a crystal growth technique such as organometallic vapor phase epitaxy OMVPE [10,11], and found that the air holes of photonic crystal can be retained even by the crystal growth technique.
Note that the growth direction was downward. Figure 6 b shows a plan-view scanning electron microscope SEM image of the photonic crystal with right-isosceles-triangle-shaped air holes before the crystal growth. It is clearly seen that the air holes were successfully embedded in the device, where the air holes become narrower towards the lower side of the device, whereas the upper parts of the air holes maintain an almost uniform shape with vertical side walls.
I then describe the lasing characteristics of the fabricated device  under the room-temperature RT continuous -wave CW condition. The corresponding experimental results are shown in Fig.
A maximum CW output power of 1. When the output power was less than 0. For an ideal Gaussian beam, M2 is known to be unity, but it increases when the beam quality is degraded due to the transverse multimode. Lasers with such a nar row beam divergence should enable unique applications that do not require any lens. We examined the direct irradiation of a sheet of paper placed 8.
The light output was set to 0. The paper was burnt, forming a small hole immediately after radiation, as shown in Fig. Although this is just a simple demonstration, it shows the potential of lens-free applications.
I have described the current status and recent developments in the field of photonic-crystal lasers. It has been shown that the band-edge effect of twodimensional photonic crystals enables large-area single longitudinal and t ransver se mode lasing oscillation, as well as complete control over the beam patterns obtained. It has been also described that a device with an output power exceeding 1.
We have witnessed the series of evolution of the small lasers over a few decades , from the 1D VCSEL to the 2D photonic crystal laser and back to the 1D. Appendix. Photonic crystal lasers: future integrated devices. Introduction. The technology of photonic crystals has produced a large variety of new devices.
Our work represents an important milestone for innovation in the field of lasers because it provides a route towards overcoming limitations in applications that suffer from low beam quality, which opens the door to a wide range of applications in material processing, laser medicine, nonlinear optics, sensing and so on. Imada, S. Noda, A. Chutinan, T. Tokuda, M. Murata, and G. Sasaki : "Coherent twodimensional lasing action in surface-emitting laser with triangular-lattice photonic crystal structure," Appl. Noda, M. Yokoyama, M.
Imada, A. Chutinan, M. Chut inan, S.
Noda, and M. Mochi zuki , "Mult idi rect ional ly di st r ibuted feedback photonic crystal lasers", Physical Review B , Vol. Sakai, E. Miyai, T.
Sakaguchi, D. Ohnishi, T. Okano, and S.
Okano, M. Imada, and S. Miyai, K. Sakai, T. Okano, W, Kunishi, D. Ohnishi, and S. Noda, "Lasers producing tailored beams", Nature , Vol. Matsubara, S. Yoshimoto, H. Saito, Y.
Jianglin, Y. Tanaka, and S. Noda, "GaN photonic-crystal surface-emitting laser at blue-violet wavelengths", Science , Vol. Kurosaka, S. Iwahashi, Y. Liang, K. Miyai, W. Kunishi, D. Liang, P. On the application level, the development of photonic crystal lasers with low threshold and increased output power is crucial for most of their proposed commercial applications.
In addition, the development of a single quantum dot laser would be of great importance for ultra-low-power laser applications, as the structure would have lower threshold than any conventional laser. On the fundamental level, the demonstration of a single quantum dot laser would open opportunities to study cavity QED and quantum optics in the solid state instead of using atoms trapped inside cavities. Finally, as part of this project, the PI will also develop an integrated research and educational program ranging from fundamental science quantum optics, quantum information science, and mesoscopic physics to engineering photonics and optoelectronics.
The PI believes that an investment into education of a new generation of researchers and technologists will enable exploitation of photonic crystals and quantum optics at their full potential in the future. Moreover, by making researchers in other fields of science familiar with his work, he will possibly create new applications and research directions.
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