Optical anisotropy in semipolar (Al,In)GaN laser waveguides

Scheibenzuber, Wolfgang G.; Schwarz, Ulrich; Veprek, Ratko G.; Witzigmann, Bernd; Hangleiter, A.

doi:10.1002/pssc.200983646

Cited by 6 publications

(4 citation statements)

References 14 publications

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“…This difference in accuracy arises from variations in the index of refraction between adjacent layers in III-nitride waveguides and the necessity to match boundary conditions between these layers. Nevertheless, the change in polarization between adjacent layers in a III-nitride waveguide (typically a couple of degrees at most) is still very close to the polarization predicted by the indicatrix construction for waves in a bulk III-nitride crystal, as predicted by theoretical calculations 38,68) and confirmed by experimental measurements. 69,70) The polarization of modes in a birefringent waveguide is often different than the usual polarization parallel (transverse electric or TE mode) and perpendicular (transverse magnetic or TM mode) to the growth plane, as discussed in more detail below.…”

Section: Waveguide Orientationsupporting

confidence: 73%

“…71) However, for waveguides on semipolar growth planes, waveguide orientations parallel to the yA-direction do not coincide with natural crystal faces (i.e., crystal planes with rational Miller indices), so mirror facets need to formed on these waveguide orientations by dry etching or polishing. 72) As cleaving is a more mature technology for fabricating mirror facets than dry etching or polishing, there have been many studies to assess the suitability of waveguide orientations perpendicular to the yA-direction for semipolar LDs, 19,24,38,[68][69][70][73][74][75] as discussed in more detail in Sect. 4.5.…”

Section: Waveguide Orientationmentioning

confidence: 99%

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Valence band states and polarized optical emission from nonpolar and semipolar III–nitride quantum well optoelectronic devices

Zhao

Speck

2014

Jpn. J. Appl. Phys.

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Nonpolar and semipolar III–nitride quantum wells (QWs) and devices have been extensively studied due to their unique valence band (VB) structure and polarized optical emission. Unlike conventional c-plane oriented III–nitride QWs, the low crystal symmetry and unbalanced biaxial stress in nonpolar and semipolar QWs separates the topmost VBs and gives rise to polarized optical emission. Since the first experimental reports on nonpolar devices, research on this topic has progressed very rapidly and has covered nonpolar m-plane and a-plane QWs and devices as well as semipolar , , and QWs and devices. Issues such as strain, plane inclination angle (with respect to the c-plane), indium composition, temperature, and their impact on QW VB structure and device performance have been extensively studied. In this paper we review the physical background and theoretical analysis of the VB states and polarized optical emission of nonpolar and semipolar structures and discuss their potential impacts on optoelectronic devices. Experimental results for nonpolar and semipolar light-emitting diodes and laser diodes will be covered along with additional discussions on the potential applications and challenges related to their unique physical properties.

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Section: Waveguide Orientationsupporting

confidence: 73%

Section: Waveguide Orientationmentioning

confidence: 99%

Valence band states and polarized optical emission from nonpolar and semipolar III–nitride quantum well optoelectronic devices

Zhao

Speck

2014

Jpn. J. Appl. Phys.

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“…[17][18][19] In nonpolar and semipolar QWs, on the other hand, the biaxial stress induces anisotropic strain, which drastically modifies the subband structures and wavefunction character [20][21][22] and induces polarized light emission.…”

Section: 16mentioning

confidence: 99%

Effects of strain on the band structure of group-III nitrides

et al. 2014

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We present a systematic study of strain effects on the electronic band structure of the group-III-nitrides (AlN, GaN and InN) in the wurtzite phase. The calculations are based on density functional theory (DFT) with band-gap-corrected approaches including hybrid functional (HSE) and quasiparticle G 0 W 0 methods. We study strain effects under realistic strain conditions, hydrostatic pressure and biaxial stress. The strain-induced modification of the band structures is found to be nonlinear; transition energies and crystal-field splittings show a strong nonlinear behavior under biaxial stress. For the linear regime around the experimental lattice parameters, we present a

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“…Studies on various semi-polar planes have shown highest values of optical gain for the in-plane projection of the c-axis [4][5][6]. The lack of any natural cleavage plane orthogonal to the in-plane projection of the c-axis on semi-polar planes has made Cl 2 -based dry etch processes the most common way to form mirror facets for semi-polar LDs [7,8].…”

mentioning

confidence: 99%

CW operation of high‐power blue laser diodes with polished facets on semi‐polar GaN substrates

et al. 2016

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Continuous wave (CW) operation of high-power blue laser diodes (LDs) with polished facets on semi-polar (202̅ 1̅) gallium nitride (GaN) substrates is demonstrated. Ridge waveguide LDs were fabricated using indium GaN waveguiding layers and GaN cladding layers. At a lasing wavelength of 452 nm, the peak two-facet CW output power from an LD with uncoated facets was 1.71 W at a current of 3 A, corresponding to an optical power density of 32.04 MW/cm 2 on each facet. The dependence of output power on current did not change with repeated CW measurements, indicating that the polished facets did not degrade under high-power CW operation. These results show that polished facets are a viable alternative to cleaved or etched facets for high-power CW semi-polar LDs.

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Optical anisotropy in semipolar (Al,In)GaN laser waveguides

Cited by 6 publications

References 14 publications

Valence band states and polarized optical emission from nonpolar and semipolar III–nitride quantum well optoelectronic devices

Valence band states and polarized optical emission from nonpolar and semipolar III–nitride quantum well optoelectronic devices

Effects of strain on the band structure of group-III nitrides

CW operation of high‐power blue laser diodes with polished facets on semi‐polar GaN substrates

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