Q. Determine the internal quantum efficiency generated within a device when it has a radiative recombination lifetime of 80 ns and total carrier recombination lifetime of 40 ns.

View solution

Q. Compute power internally generated within a double-heterojunction LED if it has internal quantum efficiency of 64.5 % and drive current of 40 mA with a peak emission wavelength of 0.82 μm.

View solution

Q. The Lambertian intensity distribution __________ the external power efficiency by some percent.

View solution

Q. A planar LED fabricated from GaAs has a refractive index of 2.5. Compute the optical power emitted when transmission factor is 0.68.

View solution

Q. A planar LED is fabricated from GaAs is having a optical power emitted is 0.018% of optical power generated internally which is 0.018% of optical power generated internally which is 0.6 P. Determine external power efficiency.

View solution

Q. For a GaAs LED, the coupling efficiency is 0.05. Compute the optical loss in decibels.

View solution

Q. In a GaAs LED, compute the loss relative to internally generated optical power in the fiber when there is small air gap between LED and fiber core. (Fiber coupled = 5.5 * 10⁻⁴ Pint)

View solution

Q. Determine coupling efficiency into the fiber when GaAs LED is in close proximity to fiber core having numerical aperture of 0.3.

View solution

Q. If a particular optical power is coupled from an incoherent LED into a low-NA fiber, the device must exhibit very high radiance.

View solution

Q. The amount of radiance in planer type of LED structures is ____________

View solution

Q. In optical fiber communication _____________ major types of LED structures are used.

View solution

Q. As compared to planar LED structure, Dome LEDs have ______________ External power efficiency ___________ effective emission area and _____________ radiance.

View solution

Q. The techniques by Burros and Dawson in reference to homo structure device is to use an etched well in GaAs structure.

View solution

Q. In surface emitter LEDs, more advantage can be obtained by using ____________

View solution

Q. Internal absorption in DH surface emitter Burros type LEDs is ____________

View solution

Q. DH surface emitter generally give ____________

View solution

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

View solution

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.

View solution

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

View solution

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.

View solution