Question
Download Solution PDFAn LED has lower output power, ________ switching speed and _______ spectral width than the LASER as an optical source.
Answer (Detailed Solution Below)
Detailed Solution
Download Solution PDFAn LED is a junction diode made from semiconductor compound gallium arsenide phosphide. LEDs used as optical fiber transmitters emit infrared radiation at a wavelength of about 850 nm (0.85 µm).
Laser is derived from Light Amplification by the Stimulated Emission of Radiation. It produces a very intense beam of light or infrared radiation which is having following properties.
• Monochromatic ( meaning consists of one wavelength)
• Coherent (meaning all parts are in phase)
• Collimated (meaning all parts travel in one and same direction)
An LED has lower output power, slower switching speed and higher spectral width than the Laser as an optical source.
| specification | Light Emitting Diode | Laser Diode |
| Working operation | It emits light by spontaneous emission. | It emits light by stimulated emission. |
| Output power | Emitted light power is relatively low, Linearly proportional to drive current | Output power is high (Few mW to GW) , Proportional to current above the threshold |
| Spectral width | Wider, 25 to 100 nm (10 to 50 THz) |
Narrower, <10-5 to 5 nm (<1 MHz to 2 MHz) |
| Speed | Slower | Faster |
| Coupled power | Moderate | High |
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