Title: Improving emission uniformity and linearizing band dispersion in nanowire arrays using quasi-aperiodicity

Abstract

For this study, we experimentally investigate a new class of quasi-aperiodic structures for improving the emission pattern in nanowire arrays. Efficient normal emission, as well as lasing, can be obtained from III-nitride photonic crystal (PhC) nanowire arrays that utilize slow group velocity modes near the Γ-point in reciprocal space. However, due to symmetry considerations, the emitted far-field pattern of such modes are often ‘donut’-like. Many applications, including lighting for displays or lasers, require a more uniform beam profile in the far-field. Previous work has improved far-field beam uniformity of uncoupled modes by changing the shape of the emitting structure. However, in nanowire systems, the shape of nanowires cannot always be arbitrarily changed due to growth or etch considerations. Here, we investigate breaking symmetry by instead changing the position of emitters. Using a quasi-aperiodic geometry, which changes the emitter position within a photonic crystal supercell (2x2), we are able to linearize the photonic bandstructure near the Γ-point and greatly improve emitted far-field uniformity. We realize the III-nitride nanowires structures using a top-down fabrication procedure that produces nanowires with smooth, vertical sidewalls. Comparison of room-temperature micro-photoluminescence (µ-PL) measurements between periodic and quasi-aperiodic nanowire arrays reveal resonances in each structure, with the simplemore » periodic structure producing a donut beam in the emitted far-field and the quasi-aperiodic structure producing a uniform Gaussian-like beam. We investigate the input pump power vs. output intensity in both systems and observe the simple periodic array exhibiting a non-linear relationship, indicative of lasing. We believe that the quasi-aperiodic approach studied here provides an alternate and promising strategy for shaping the emission pattern of nanoemitter systems.« less

Authors:

Anderson, P. Duke ^[1]; Koleske, Daniel D. ^[2]; Povinelli, Michelle L. ^[3]; Subramania, Ganapathi ^[2]

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+ Show Author Affiliations

1. Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States); Univ. of Southern California, Los Angeles, CA (United States). Ming Hsieh Dept. of Electrical Engineering
2. Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States)
3. Univ. of Southern California, Los Angeles, CA (United States). Ming Hsieh Dept. of Electrical Engineering

Publication Date:

2017-10-01

Research Org.:

Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

Sponsoring Org.:

USDOE National Nuclear Security Administration (NNSA)

OSTI Identifier:

1393298

Alternate Identifier(s):

OSTI ID: 1477877

Report Number(s):

SAND-2017-10444J
Journal ID: ISSN 2159-3930

Grant/Contract Number:  

AC04-94AL85000; NA-0003525; NA0003525

Resource Type:

Published Article

Journal Name:

Optical Materials Express

Additional Journal Information:

Journal Name: Optical Materials Express Journal Volume: 7 Journal Issue: 10; Journal ID: ISSN 2159-3930

Publisher:

Optical Society of America (OSA)

Country of Publication:

United States

Language:

English

Subject:

42 ENGINEERING; 77 NANOSCIENCE AND NANOTECHNOLOGY