Dependence of Beam Quality on Optical Intensity Asymmetry in In-Phase Coherently Coupled VCSEL Array

• Dependence of beam quality on optical intensity asymmetry among elements in in-phase coherently coupled vertical cavity surface emitting lasers array is analyzed using the finite-difference time domain solutions software. The analysis results reveal that the coupling efficiency of in-phased array decreases and the divergence increases as the level of optical intensity asymmetry increases. Furthermore, an addressable separated-contact three-element triangular in-phased array is fabricated and measured to verify the analysis. The array exhibits a relatively high of coupling efficiency of 24% and a near-diffraction-limit divergence of 3.2° (1.12 times of the diffraction limit, D.L.) when the optical intensity of each element is adjusted to be uniform. By degrading the optical intensity symmetry, the coupling efficiency decreases to 17.07% and the divergence increases to 4.03° ( 1.37× D.L.). After that, a much larger 10× 10 array exhibiting in-phase characteristics is produced and its beam quality and optical uniformity are measured and discussed. Analysis and experiment results demonstrate that symmetric optical intensity among elements is essential for in-phased array to achieve high beam quality. Employing separate contacts in the array is proved an effective way to obtain uniform optical intensity and achieve high beam quality.

Ämnesord

NATURVETENSKAP  -- Kemi -- Analytisk kemi (hsv//swe)

NATURAL SCIENCES  -- Chemical Sciences -- Analytical Chemistry (hsv//eng)

NATURVETENSKAP  -- Fysik -- Atom- och molekylfysik och optik (hsv//swe)

NATURAL SCIENCES  -- Physical Sciences -- Atom and Molecular Physics and Optics (hsv//eng)

NATURVETENSKAP  -- Fysik -- Annan fysik (hsv//swe)

NATURAL SCIENCES  -- Physical Sciences -- Other Physics Topics (hsv//eng)

Nyckelord

in-phase

coupling efficiency

beam divergence

VCSEL array

optical intensity asymmetry

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