P‐99: A Backlight Based on a Laser Diode and Its Design Considerations

Inaba, Yusuke; Imai, Kenichi; Fujieda, Ichiro; Onishi, Ikuo

doi:10.1889/1.3069459

Cited by 12 publications

(8 citation statements)

References 7 publications

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“…10 Additionally, the ability to fabricate single mode VCSELs is not only a benefit for data transmission but also makes VCSELs highly sensitive devices for atomic clocks. [11][12][13][14][15] Finally, because VCSELs have emission normal to the substrate, they can be fabricated into high density 2D arrays, making III-nitride VCSELs ideal for visible and UV-A applications requiring high power density emission, including pico-projectors, 16 micro-displays, [17][18][19][20] backlighting for small electronics, 21 laser based lighting, [22][23][24] and bio-sensing. 25 In the arsenides, high power VCSEL arrays are now being manufactured to yield 9.6 kW emission for rapid industrial heating, proving the potential for these low power devices to yield high power arrays.…”

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confidence: 99%

Nonpolar III-nitride vertical-cavity surface-emitting lasers incorporating an ion implanted aperture

Leonard

Cohen

Yonkee

et al. 2015

Applied Physics Letters

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We report on our recent progress in improving the performance of nonpolar III-nitride vertical-cavity surface-emitting lasers (VCSELs) by using an Al ion implanted aperture and employing a multi-layer electron-beam evaporated ITO intracavity contact. The use of an ion implanted aperture improves the lateral confinement over SiNx apertures by enabling a planar ITO design, while the multi-layer ITO contact minimizes scattering losses due to its epitaxially smooth morphology. The reported VCSEL has 10 QWs, with a 3 nm quantum well width, 1 nm barriers, a 5 nm electron-blocking layer, and a 6.95-λ total cavity thickness. These advances yield a single longitudinal mode 406 nm nonpolar VCSEL with a low threshold current density (∼16 kA/cm2), a peak output power of ∼12 μW, and a 100% polarization ratio. The lasing in the current aperture is observed to be spatially non-uniform, which is likely a result of filamentation caused by non-uniform current spreading, lateral optical confinement, contact resistance, and absorption loss.

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confidence: 99%

Nonpolar III-nitride vertical-cavity surface-emitting lasers incorporating an ion implanted aperture

Leonard

Cohen

Yonkee

et al. 2015

Applied Physics Letters

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“…6 Its applications for displays include a laser phosphor display (LPD) 7,8 and a projector engine. 9,10 We have also proposed a backlight for a liquid crystal display 11 and an energy-harvesting LPD. 12,13 For a color display, it is desired to have phosphor materials emitting in three primary colors.…”

Section: Introductionmentioning

confidence: 99%

Angle-resolved photoluminescence spectrum of a uniform phosphor layer

Fujieda

Ohta

2017

AIP Advances

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A photoluminescence spectrum depends on an emission angle due to self-absorption in a phosphor material. Assuming isotropic initial emission and Lambert-Beer’s law, we have derived simple expressions for the angle-resolved spectra emerging from the top and bottom surfaces of a uniform phosphor layer. The transmittance of an excitation light through the phosphor layer can be regarded as a design parameter. For a strongly-absorbing phosphor layer, the forward flux is less intense and more red-shifted than the backward flux. The red-shift is enhanced as the emission direction deviates away from the plane normal. When we increase the transmittance, the backward flux decreases monotonically. The forward flux peaks at a certain transmittance value. The two fluxes become similar to each other for a weakly-absorbing phosphor layer. We have observed these behaviors in experiment. In a practical application, self-absorption decreases the efficiency of conversion and results in angle-dependent variations in chromaticity coordinates. A patterned phosphor layer with a secondary optical element such as a remote reflector alleviates these problems.

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“…Studies of using lasers as the light source of a backlight are not new at all [5,6]. Most of these studies, however, focus more on the optical characteristics of lasers only and, therefore, do not sufficiently discuss thermal management.…”

Section: Introductionmentioning

confidence: 99%

Paper No 9.4: Heat Dissipation Performance of Laser Backlight for Liquid Crystal Television Displays

Nagase

Niikura

Shinozaki

et al. 2013

Symp Digest of Tech Papers

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The authors have developed the laser backlight for displays that uses laser diodes (LDs) for the red light sources. While laser beams are favorable because of their high color purity, they develop extremely disadvantageous thermal characteristics. Therefore, thermal management is a critical issue for LDs used as display light sources. As for the backlight used on a large screen flat panel display in particular, where light sources with high heat flux are laid out in a dispersed fashion, the cooling performance of the light sources directly influences the product performance and quality. The authors used a CFD simulation to review a cooling system optimum for the laser backlight.

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P‐99: A Backlight Based on a Laser Diode and Its Design Considerations

Abstract: We have constructed an edge‐lit backlight by using a blue‐emitting laser diode, an optical fiber and a YAG‐based phosphor. White light output was obtained from the backlight surface. We discuss some design issues and expect a high efficiency and a wide gamut for such a backlight.

Cited by 12 publications

References 7 publications

Nonpolar III-nitride vertical-cavity surface-emitting lasers incorporating an ion implanted aperture

Nonpolar III-nitride vertical-cavity surface-emitting lasers incorporating an ion implanted aperture

Angle-resolved photoluminescence spectrum of a uniform phosphor layer

Paper No 9.4: Heat Dissipation Performance of Laser Backlight for Liquid Crystal Television Displays

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