Annular Bragg defect mode resonators

Scheuer, Jacob; Yariv, Amnon

doi:10.1364/josab.20.002285

Cited by 74 publications

(43 citation statements)

References 21 publications

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“…[9][10][11] These devices, known as annular Bragg resonators ͑ABRs͒, are designed to support azimuthally propagating modes, with energy concentrated within a radial defect region or in a central pillar by radial Bragg reflection. Compared to conventional resonators based on total-internal reflection ͑TIR͒, the employment of the Bragg reflection mechanism offers improved control over the resonator parameters ͑Q, V mode , etc.͒ and allows for engineering unique mode profiles.…”

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Lasing from a circular Bragg nanocavity with an ultrasmall modal volume

Scheuer

Green

DeRose

et al. 2005

Applied Physics Letters

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We demonstrate single-mode lasing at telecommunication wavelengths from a circular nanocavity employing a radial Bragg reflector. Ultrasmall modal volumes and submilliwatt pump thresholds level are observed for lasers with InGaAsP quantum well active membrane. The electromagnetic field is shown to be tightly confined within the 300 nm central pillar of the cavity. The quality factors of the resonator modal fields are estimated to be on the order of a few thousands. © 2005 American Institute of Physics. ͓DOI: 10.1063/1.1947375͔The quest for the ultimate localization of light has been one of the central directions in contemporary research in many fields, such as integrated optics, quantum communication and computation, sensing, and more. 1-3 Optical nanocavities with high-quality factors ͑Q͒ and small modal volume ͑V mode ͒ are key elements for a wide variety of applications, such as functional building blocks for integrated optical circuits, lasers, optical traps, and optical logic. 4,5 In the past few years, much attention was focused on decreasing the modal volume and improving the Q of photonic crystal ͑PC͒ defect cavities by carefully optimizing the position, dimensions, and shape of the holes composing the crystal. [6][7][8][9] This optimization procedure attempts to tune the effective length of the cavity to the maximal reflection frequency of the PC reflector and is generally conducted numerically. The main disadvantage of this process is the enormous number of parameters to be optimized and the endless number of configurations that potentially need to be considered.Recently, we have proposed and demonstrated a novel class of circular resonators that are based on optimally designed radial Bragg reflectors. 9-11 These devices, known as annular Bragg resonators ͑ABRs͒, are designed to support azimuthally propagating modes, with energy concentrated within a radial defect region or in a central pillar by radial Bragg reflection. Compared to conventional resonators based on total-internal reflection ͑TIR͒, the employment of the Bragg reflection mechanism offers improved control over the resonator parameters ͑Q, V mode , etc.͒ and allows for engineering unique mode profiles. Compared to PC defect resonators, the radial symmetry of ABRs allows for analytical engineering the Bragg reflector for optimized Q and smaller modal volume. These properties make the ABR structure highly suitable for realizing ultracompact cavities, especially if they are designed for the mode with angular modal number m = 0. The m = 0 mode is an interesting solution of a disk Bragg resonator consisting of a disk surrounded by a radial Bragg stack ͑see Fig. 1͒. Unlike other solutions with nonzero angular modal numbers, the m = 0 mode is nondegenerate and features maximum intensity at the center of the device. This mode cannot be supported in conventional cavities because the propagation direction of the waves is perpendicular to the cavity interfaces.In this letter, we report on the observation of single mode lasing from a Bragg-based dis...

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Lasing from a circular Bragg nanocavity with an ultrasmall modal volume

Scheuer

Green

DeRose

et al. 2005

Applied Physics Letters

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“…7,8 These devices, annular Bragg resonators (ABRs), offer smaller dimensions than those of conventional resonators that employ total internal ref lection while retaining a high Q. In addition, such structures exhibit superior sensitivity compared with conventional resonators for biological and chemical sensing applications.…”

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“…Since the H z polarization is more conf ined than the E z polarization and the optical gain of the compressively strained quantum-well structure used favors the H z polarization, 14 we optimized the radial structure to this polarization. 8 To facilitate the fabrication of the devices we adopted a mixed Bragg order approach. 8 The highindex Bragg layers (n eff 2.8) were 3͞4l wide (second order), and the low-index layers (n eff 1.0 for air gaps and n eff 1.54 for adhesive-filled gaps) were l͞4 wide (first order).…”

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“…8 To facilitate the fabrication of the devices we adopted a mixed Bragg order approach. 8 The highindex Bragg layers (n eff 2.8) were 3͞4l wide (second order), and the low-index layers (n eff 1.0 for air gaps and n eff 1.54 for adhesive-filled gaps) were l͞4 wide (first order). In addition to the relaxed fabrication tolerances, such a layer structure improves the vertical confinement (larger material f illing factor) and induces eff icient vertical emission.…”

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Low-threshold two-dimensional annular Bragg lasers

et al. 2004

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Lasing at telecommunication wavelengths from annular resonators employing radial Bragg ref lectors is demonstrated at room temperature under pulsed optical pumping. Submilliwatt pump threshold levels are observed for resonators with 0.5 -1.5-wavelength-wide defects of radii 7 8 mm. The quality factors of the resonator modal fields are estimated to be of the order of a few thousand. The electromagnetic field is shown to be guided by the defect. Good agreement is found between the measured and the calculated spectra. © 2004 Optical Society of America OCIS codes: 140.4780, 140.5960, 250.3140, 230.1480. Ring resonators are versatile elements with various applications ranging from telecommunication and sensing to basic scientif ic research. -5During the past few years, considerable effort has been focused on improving the quality factors (Q) of resonators and reducing their modal volume (see, e.g., Refs. 5 and 6 and references therein).Recently we proposed a novel type of annular resonator based on radial Bragg ref lection. 7,8 These devices, annular Bragg resonators (ABRs), offer smaller dimensions than those of conventional resonators that employ total internal ref lection while retaining a high Q. In addition, such structures exhibit superior sensitivity compared with conventional resonators for biological and chemical sensing applications. 9This class of resonators is closely related to the family of circulargrating distributed Bragg ref lector resonators, which also exhibit lasing patterns with low angular propagation coeff icients. 10,11

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“…14 Since optical emission and gain from the compressively strained quantum wells favor TE-polarized electric fields, 20 the ABR devices fabricated used gratings designed for this polarization. In order to simplify the design calculations, an effective index n eff = 2.8 (found with a numerical mode solver) was used for the TE-polarized slab mode in the transferred InGaAsP membrane.…”

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Vertically emitting annular Bragg lasers using polymer epitaxial transfer

Green

Scheuer

DeRose

et al. 2004

Applied Physics Letters

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Fabrication of a planar semiconductor microcavity, composed of cylindrical Bragg reflectors surrounding a radial defect, is demonstrated. A versatile polymer bonding process is used to transfer active InGaAsP resonators to a low-index transfer substrate. Vertical emission of in-plane modes lasing at telecom wavelengths is observed under pulsed optical excitation with a submilliwatt threshold. Recently, a new ring cavity geometry, based on optimally designed cylindrical Bragg reflectors surrounding a radial defect, was proposed. 14,15 Resonators of this class, known as annular Bragg resonators (ABRs), are designed to support azimuthally propagating modes, with energy concentrated within the defect region by radial Bragg reflection. Optical modes with an electric field having the form E͑r , , z͒ = E͑r , z͒e im have been analyzed using several techniques, including conformal transformation, a transfer matrix approach, coupled mode theory, and finite-difference time-domain simulations. ABR devices are of great interest for their superior sensitivity in biological and chemical sensing applications when compared to conventional total internal reflection (TIR) based resonators. 16 This letter describes the fabrication and experimental demonstration of laser action in a semiconductor annular Bragg resonator.Annular Bragg resonators with high contrast Bragg reflectors were realized in active semiconductor material. The semiconductor medium consisted of a 250-nm-thick InGaAsP layer (n Ϸ 3.35 at = 1.55 m) on top of an InP substrate. The InGaAsP layer included six 75-Å-wide compressively strained InGaAsP quantum wells positioned at the center, with peak photoluminescence occurring at 1559 nm. Epitaxial layers were grown by MOCVD.The ABR fabrication process, illustrated in Fig. 1, proceeded as follows. First, a SiO 2 etch mask layer was deposited by PECVD. A layer of PMMA electron beam resist was then applied by spin-coating. The desired ABR geometry was then defined using a Leica Microsystems EBPG 5000+ direct electron beam writer operating at 100 kV. After development, the PMMA patterns were transferred into the SiO 2 etch mask layer by inductively coupled plasma reactive ion etching (ICP-RIE) using C 4 F 8 plasma. The remaining PMMA was removed with a gentle isotropic O 2 plasma step. The SiO 2 then served as a hard mask for pattern transfer into the active InGaAsP layer, using an ICP-RIE etch employing HI / Ar chemistry. 17 The patterns were etched to a depth of ϳ325 nm. The remaining SiO 2 hard mask was then stripped in a buffered hydrofluoric acid solution. A scanning electron microscope (SEM) image of an ABR device at this stage is shown in Fig. 2(a). To achieve strong vertical confinement, the InGaAsP membrane must be clad by low-index material both above and below. An epitaxial layer transfer technique, 18 using an UV-curable optical adhesive (Norland Products NOA 73, n Ϸ 1.54 at = 1.55 m), was adopted to flip-bond the patterned semiconductor sample to a transparent sapphire substrate. Subsequently, the

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Annular Bragg defect mode resonators

Cited by 74 publications

References 21 publications

Lasing from a circular Bragg nanocavity with an ultrasmall modal volume

Lasing from a circular Bragg nanocavity with an ultrasmall modal volume

Low-threshold two-dimensional annular Bragg lasers

Vertically emitting annular Bragg lasers using polymer epitaxial transfer

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