Experimental investigation of the performance of an annular aperture and a circular aperture on the same very-small-aperture laser facet

Abstract

A very-small-aperture laser (VSAL) with a circular aperture has a trade-off between the spot size and the output power. A nanometric annular aperture is fabricated to overcome this difficulty. The advantages of the annular aperture are demonstrated by measuring and comparing its near-field intensity distribution with that of a circular aperture. These apertures are fabricated on the same VSAL to ensure that they are under the same illumination conditions. The experimental results indicate that an annular aperture produces a smaller spot size and a higher peak intensity than a circular aperture. The confinement effect and the enhancement effect are attributed to the convergence of the power flow that passes through the annular aperture. The observed enhancement effect decreases when the distance from the VSAL facet is increased, but it does not vanish even when the distance is as large as 3.5 microm.

Tuning the resonant wavelength of a nanometric bow-tie aperture by altering the relative permittivity of the dielectric substrate

“…For these apertures, it is difficult to obtain a small spot size and a high output power simultaneously. In order to overcome this difficulty, researchers have proposed many novel apertures, such as "C"-shaped apertures [4][5][6], "I"-shaped apertures [7,8], "L"-shaped apertures [9], annular apertures [10,11], and bow-tie apertures [12][13][14][15][16]. These apertures have potential for nanoaperture enhanced photodetectors [17], subwavelength waveguides [18], verysmall-aperture lasers [19,20], and in nanolithography [21].…”