SEL
Key Features:
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Low threshold current
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Easy single-mode output implementation
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Facilitates 2D array integration
EEL
Key Features:
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Edge-emission parallel to the semiconductor surface
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Optical coupling capability at both ends of the chip
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Superior beam quality and higher output power
VCSEL
Key Features:
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Low threshold current
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Stable single-wavelength operation
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Simplified two-dimensional array integration
Technical Specifications:
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Primary Wavelength: 850nm band
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Material System: GaAs/AlGaAs composition tuning
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Manufacturing: Mature and cost-effective, suitable for large-scale mass production
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Multi-junction cascade structure design: higher output optical power can be achieved at the same drive current, enhancing optical power density
FP
Spectral Characteristics:
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Multi-longitudinal-mode output: Weak wavelength selectivity results in broad spectral width (~1–5 nm).
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Lower coherence: Less suitable for applications requiring precise wavelength stability.
Advantages:
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Cost-effective: Simple structure enables low manufacturing costs.
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High output power: Suitable for power-sensitive applications.
Applications:
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Fiber-optic communications: Primarily used in 1G/10G optical modules for medium-distance transmission (≤40 km).
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Industrial sensing: Where spectral purity is less critical.
DFB
Spectral Characteristics:
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Narrow linewidth (~0.1 nm or less).
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High side-mode suppression ratio (SMSR) (>40 dB).
Advantages:
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Wavelength stability: Ideal for dense wavelength-division multiplexing (DWDM).
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Low chirp: Critical for high-speed modulation.
Applications:
EML
Modulation Mechanism:
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The DFB section operates under a constant bias current and provides stable, low-chirp light.
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The EAM modulates light intensity via the Franz-Keldysh effect (voltage-dependent absorption).
Advantages:
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High-speed modulation (up to 100 Gbps+).
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Low power consumption compared to externally modulated lasers.
Applications:
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Long-haul/coherent communications (e.g., 400G ZR modules).
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5G fronthaul/data center interconnects (DCI).
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