Vikram Sekar/MicroLEDs vs. Lasers - The Linewidth Tradeoff

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MicroLEDs vs. Lasers - The Linewidth Tradeoff

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The critical debate shaping hyperscale datacenter interconnects: MicroLEDs versus DFB lasers. This analysis unpacks the fundamental "linewidth tradeoff," showing how spectral purity imposes strict speed limits on optical links via chromatic dispersion. You will contrast the high-speed, narrow-linewidth DFB lasers with the power-efficient, emerging "wide-but-slow" MicroLED array approach.

Contents

What You'll Find Inside

  • MicroLEDs vs. Lasers: The Linewidth Tradeoff: An explanation of how spectral purity (linewidth) dictates speed limits for optical links.

  • Lumentum, Coherent, and DFB Lasers: Analysis of DFB laser dominance in 200G/lane EMLs (Lumentum) and the competition for Continuous-Wave (CW) lasers in Co-Packaged Optics (CPO).

  • Laser Linewidth, RIN, and Power: Definitions of Linewidth (FWHM) and Relative Intensity Noise (RIN), including a comparison of Lumentum and Coherent CPO laser specs.

  • The Case for MicroLEDs: Benefits and Challenges: Review of industry players (Microsoft, Avicena, Credo) and the MicroLED's "wide-but-slow" array approach, with details on benefits (low power, reliability) and system challenges (focusing optics, electrical gearboxing).

  • Why linewidth matters for data rates: A mathematical and numerical demonstration of how chromatic dispersion limits data rates, contrasting MicroLED (40ps pulse spread) versus DFB laser (0.001ps pulse spread) performance.

TheLinewidthTradeoff.epub
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The Linewidth Tradeoff - Vikram Sekar.pdf
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