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PHOTONIC CRYSTAL LASER meetings

Foreign code F180009427
File No. 外0154,5712
Posted date Jun 28, 2018
Country WIPO
International application number 2018JP007246
International publication number WO 2018159606
Date of international filing Feb 27, 2018
Date of international publication Sep 7, 2018
Priority data
  • P2017-035887 (Feb 28, 2017) JP
Title PHOTONIC CRYSTAL LASER meetings
Abstract A photonic crystal laser 10 is a laser having a configuration in which a light emitting layer (active layer 12) for producing light including light of a wavelength λL, and a two-dimensional photonic crystal layer 11 are laminated, the two-dimensional photonic crystal layer 11 having a refractive index distribution formed by two-dimensionally arranging, on a plate-like substrate 112, different refractive index regions (holes 111) having refractive indexes different from that of the substrate 112. In the two-dimensional photonic crystal layer 11, the different refractive index regions are arranged at positions displaced from the lattice points of a fundamental two-dimensional lattice having a periodicity which is determined such that a resonant state of the light of the wavelength λL is formed by forming a two-dimensional standing wave, and such that the light of the wavelength λL is not externally emitted. A position displacement vector Δr↑ which indicates the displacements of the positions of the different refractive index regions in the respective lattice points from the lattice points is expressed by Δr↑ = d·sin(±G'↑·r↑ + ψ0)·(cos(L(φ + φ0)) and sin(L(φ + φ0))), using: an inverse lattice vector G'↑ = ±(kx ± |k↑|(sinθcosφ)/neff, ky ± |k↑|(sinθsinφ)/neff) expressed by a wave number vector k↑ = (kx, ky) of the light of the wavelength λL in the two-dimensional photonic crystal layer 11, an effective refractive index neff of the two-dimensional photonic crystal layer, an azimuth angle φ from a predetermined reference line extending in a predetermined direction from a predetermined origin of the fundamental two-dimensional lattice, an arbitrary constant φ0, and an expanding angle θ of a laser beam; a position vector r↑ of each of the lattice points; arbitrary constants d and ψ0; and an integer L other than 0.
Outline of related art and contending technology BACKGROUND ART
Of the sample or a small amount of fine processing is used to detect the light source, wherein the processing or to enhance the accuracy of the detection, condenses the laser beam can be as small as possible is demanded.However, simply referred to as a light condensing lens for condensing the laser beam only, the size of the spot diameter of the laser beam, the wavelength of the laser and a condensing lens of the diffraction determined by the numerical aperture cannot be below a limit value.
Patent Document 1 is, to reduce the spot diameter that is suitable as a laser generating a laser beam, a laser beam having the active layer and the photonic crystal (photonic crystal laser) is described.Photonic crystal laser, current is injected into the active layer are generated by the light, the refractive index of the photonic crystal corresponding to the period of only a specific wavelength of light selectively amplified by the interference, to cause laser oscillation.The period of the refractive index in the photonic crystal, in general, and the same order as the wavelength of light.Patent Document 1 of the photonic crystal laser, the photonic crystal is constituted, in the plate-like base material, base material is a refractive index different from refractive index region in a circular area, in circumferential direction of the ring is disposed so as to align.Each of the modified refractive index region, that passes through the center thereof extending in the radial direction of the ring has a shape asymmetrical with respect to the axis.By having such a photonic crystal, photonic crystal laser of Patent Document 1, as shown in Fig. 15 (a), the annular ring 81 is a cross-sectional view in the radial direction (direction indicated by the arrow in the figure) the laser beam having a polarization.Hereinafter, such a laser beam is' radially polarized annular laser beam ' is called.
Such a radially polarized annular laser beam by focusing, the focus in the vicinity of the electric field is generated in the optical axis direction, the diffraction limit that is less than the beam diameter of the laser beam is obtained.In the prior art, a small beam diameter to the wavelength of the optical axis direction is very narrow (short) 1 only in the region was not obtained, by using a radially polarized annular laser beam 10 in the wavelength region longer than can be obtained.
In addition, as shown in Fig. 15 (b), a radially polarized annular laser beam 83 is focused in the lens, the annular portion of the laser beam is refracted at the electric field of the radially polarized, (z direction) in a direction parallel to the laser beam of the component occurs.Polarized light having such a component is used, for example Raman scattering measurement, a laser beam in the case of using polarized light perpendicular to the scattering does not occur can be observed, an advantage (see Non-Patent Document 1).
Scope of claims (In Japanese)[請求項1]
 波長λ Lの光を含む光を生じさせる発光層と、板状の母材に、該母材とは屈折率が異なる異屈折率領域が2次元的に配置されることにより屈折率分布が形成されて成る2次元フォトニック結晶層とが積層された構成を有するレーザであって、
 該2次元フォトニック結晶層において各異屈折率領域が、2次元定在波を形成することによって前記波長λ Lの光の共振状態を形成し且つ該波長λ Lの光を外部に出射させないように定められる周期性を持つ基本2次元格子の各格子点からずれた位置に配置されており、
 前記各格子点における異屈折率領域の位置の、該格子点からのずれの大きさが、前記基本2次元格子の所定の原点から径方向及び周方向に向かってそれぞれ所定の周期で変化する変調を有し、該格子点からのずれの方向が、該原点と該格子点を結ぶ直線の方向によって異なる
ことを特徴とするフォトニック結晶レーザ。
[請求項2]
 波長λ Lの光を含む光を生じさせる発光層と、板状の母材に、該母材とは屈折率が異なる異屈折率領域が2次元的に配置されることにより屈折率分布が形成されて成る2次元フォトニック結晶層とが積層された構成を有するレーザであって、
 該2次元フォトニック結晶層において各異屈折率領域が、2次元定在波を形成することによって前記波長λ Lの光の共振状態を形成し且つ該波長λ Lの光を外部に出射させないように定められる周期性を持つ基本2次元格子の各格子点からずれた位置に配置されており、
 前記各格子点における異屈折率領域の位置の、該格子点からのずれを表す位置ずれベクトルΔr↑が、前記2次元フォトニック結晶層内における前記波長λ Lの光の波数ベクトルk↑=(k x, k y)、前記2次元フォトニック結晶層の有効屈折率n eff、前記基本2次元格子の所定の原点から所定の方向に延びる所定の基準線からの方位角φ、任意の定数φ 0、及びレーザビームの拡がり角θを用いて表される逆格子ベクトルG'↑=±(k x±|k↑|(sinθcosφ)/n eff, k y±|k↑|(sinθsinφ)/n eff)、前記各格子点の位置ベクトルr↑、任意の定数d及びψ 0、並びに0を除く整数Lを用いて、
 Δr↑=d・sin(±G'↑・r↑+ψ 0)・(cos(L(φ+φ 0)), sin(L(φ+φ 0)))
で表されることを特徴とするフォトニック結晶レーザ。
[請求項3]
 前記Lの値が+1、前記φ 0の値が90°であることを特徴とする請求項2に記載のフォトニック結晶レーザ。
[請求項4]
 前記異屈折率領域の平面形状が円形、楕円形又は三角形以上の多角形であることを特徴とする請求項1~3のいずれかに記載のフォトニック結晶レーザ。
[請求項5]
 前記異屈折率領域の平面形状が円形又は六角形以上の多角形であることを特徴とする請求項4に記載のフォトニック結晶レーザ。
  • Applicant
  • ※All designated countries except for US in the data before July 2012
  • KYOTO UNIVERSITY
  • NATIONAL UNIVERSITY CORPORATION KYOTO INSTITUTE OF TECHNOLOGY
  • Inventor
  • NODA, Susumu
  • KITAMURA, Kyoko
  • YONE, Masako
IPC(International Patent Classification)
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