Q. DH surface emitter generally give ____________

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Q. A DH surface emitter LED has an emission area diameter of 60 μm. Determine emission area of source.

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Q. Estimate optical power coupled into fiber of DH SLED having emission area of 1.96*10⁻⁵, radiance of 40 W/rcm², numerical aperture of 0.2 and Fresnel reflection coefficient of 0.03 at index matched fiber surface.

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Q. In a multimode fiber, much of light coupled in the fiber from an LED is ____________

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Q. Determine the overall power conversion efficiency of lens coupled SLED having forward current of 20 mA and forward voltage of 2 V with 170 μW of optical power launched into multimode step index fiber.

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Q. The overall power conversion efficiency of electrical lens coupled LED is 0.8% and power applied 0.0375 V. Determine optical power launched into fiber.

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Q. Mesa structured SLEDs are used ____________

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Q. The InGaAsP is emitting LEDs are realized in terms of restricted are ____________

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Q. The active layer of E-LED is heavily doped with ____________

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Q. Intrinsically _________________ are a very linear device.

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Q. Linearizing circuit techniques are used for LEDs.

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Q. The internal quantum efficiency of LEDs decreasing _______________ with ________________ temperature.

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Q. To utilize _____________________ of SLDs at elevated temperatures, the use of thermoelectric coolers is important.

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Q. For particular materials with smaller bandgap energies operating in _____________ wavelength, the linewidth tends to ______________

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Q. The active layer composition must be adjusted if a particular center wavelength is desired.

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Q. In optical fiber communication, the electrical signal dropping to half its constant value due to modulated portion of optical signal corresponds to _______

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Q. The optical 3 dB point occurs when currents ratio is equal to _____________

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Q. The optical bandwidth is _____________ the electrical bandwidth.

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Q. When a constant d.c. drive current is applied to device, the optical o/p power is 320 μm. Determine optical o/p power when device is modulated at frequency 30 MHz with minority carrier recombination lifetime of LED i.e. 5ns.

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Q. The optical power at 20 MHz is 246.2 μW. Determine dc drive current applied to device with carrier recombination lifetime for LED of 6 ns.

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