For efficient operation, should a detector have a high or low  responsivity at the operating wavelength?

1 Answer

Answer :

High.

Related questions

Description : The minimum optical power a light detector can receive and still produce a usable electrical output signal. ∙ A. light responsivity ∙ B. light sensitivity ∙ C. light collectivity ∙ D. illumination

Last Answer : B. light sensitivity

Description : The term responsivity as it applies to a light detector is best described as ∙ A. the time required for the signal to go from 10 to 90 percent of maximum amplitude ∙ B. the ratio of the diode ... . the ratio of the input power to output power ∙ D. the ratio of output current to input current

Last Answer : the ratio of the diode output current to the input optical power

Description : For a light detector, responsivity is measured in: a. amps per watt b. µW per amp c. mA per joule d. µsec per µW

Last Answer : a. amps per watt

Description : The term responsivity as it applies to a light detector is best described as.

Last Answer : the ratio of the diode output current to the input optical power

Description : Define responsivity.

Last Answer : The ratio of the optical detector's output photocurrent in amperes to the incident optical power in watts.

Description : Silica (pure glass) fibers are used because of their low intrinsic material absorption at the wavelengths of operation. This wavelength of operation is between two intrinsic absorption regions. What are these two regions called? What are the wavelengths of operation for these two regions?

Last Answer : Ultraviolet absorption region (below 400 nm) and infrared absorption region (above 2000 nm).

Description : Describe the operation of an optical detector

Last Answer : It is a transducer that converts an optical signal into an electrical signal. It does this by generating an electrical current proportional to the intensity of incident optical radiation.

Description : Which dispersion mechanism (material or waveguide) is a function of the size of the fiber's core relative to the wavelength of operation?

Last Answer : Waveguide dispersion.

Description : What happens to the fundamental mode as the operating wavelength becomes longer than the single mode cutoff wavelength?

Last Answer : The fundamental mode becomes increasingly lossy.

Description : Scattering losses are caused by the interaction of light with density fluctuations within a fiber. What are the two scattering mechanisms called when the size of the density fluctuations is (a) greater than and (b) less than one-tenth of the operating wavelength?

Last Answer : . (a) Mie scattering; (b) Rayleigh scattering.

Description : Why is class C operation more efficient than class A operation?

Last Answer : The amplifier operates (and therefore uses power) for less time in class C than in class A.

Description : A measure of conversion efficiency of a photodetector. ∙ A. Efficiency ∙ B. Responsivity ∙ C. Dark current ∙ D. Spectral response

Last Answer : B. Responsivity

Description : What parameter of light detector determines the range or system length that can be achieved for a given wavelength? ∙ a. Transit time ∙ b. Spectral response ∙ c. Dark current ∙ d. Responsitivity

Last Answer : ∙ b. Spectral response

Description : List the types of materials used in fabricating low-loss, long wavelength optical fibers.

Last Answer : Heavy-metal fluorides, chalcogenide glasses, and crystalline materials.

Description : Sound waves transmitted from a source are sometimes weak when they reach the detector. What instrument is needed to boost the weak signal?

Last Answer : An amplifier.

Description : In the output of an ac error detector, what indicates the (a) direction and (b) amount of control necessary for correspondence?

Last Answer : (a) Phase. (b) Amplitude.

Description : An error signal is the difference between what two quantities fed to the CT (error detector)?

Last Answer : Input signal and feedback.

Description : Why is detector saturation not generally a problem in fiber optic communications systems?

Last Answer : Because fiber optic communications systems operate at low optical power levels.

Description : What are the four most common materials used in semiconductor detector fabrication?

Last Answer : Silicon, gallium arsenide, germanium, and indium phosphide.

Description : What is the function of the detector?

Last Answer : To extract the modulating audio signal.

Description : How can a peak detector for pam be modified to detect pdm?

Last Answer : By making the time constant for charging the capacitor at least 10 times the maximum received pulse width.

Description : What is the time constant of the resistor and capacitor in a peak detector for pam?

Last Answer : At least 10 times the interpulse period.

Description : What characteristic of a pulse does a peak detector sample?

Last Answer : Pulse amplitude or pulse duration

Description : In its simplest form, what functions must a radar detector be capable of performing?

Last Answer : Detecting the presence of rf energy.

Description : How is a quadrature detector changed when used for phase demodulation?

Last Answer : The quadrature grid signal is excited by a reference from the transmitter.

Description : Name two advantages of the gated-beam detector.

Last Answer : Extreme simplicity, few components, and ease of adjustment.

Description : What condition must exist on both the limiter and quadrature grids for current to flow in a gated-beam detector?

Last Answer : Both grids must be positively biased

Description : What circuit functions does the tube in a gated-beam detector serve?

Last Answer : Limits, detects, and amplifies.

Description : What is the primary advantage of a ratio detector?

Last Answer : Suppresses amplitude noise without limiter stages.

Description : What is the function of an fm detector?

Last Answer : Converting frequency variations of received fm signals to amplitude variations

Description : What is the simplest form of fm detector?

Last Answer : Slope detector.

Description : which components act as the filter network in the diode detector?

Last Answer : C1 and R1.

Description : To what circuit arrangement is a common-base detector equivalent?

Last Answer : A diode detector followed by a stage of audio amplification.

Description : Which junction acts as the detector in a common-base detector?

Last Answer : Emitter-base junction.

Description : How is the output signal developed in the common-emitter detector?

Last Answer : By the collector current flow through R4.

Description : Which junction of the transistor in the common-emitter detector detects the modulation envelope?

Last Answer : Emitter-base junction

Description : Under what circuit conditions would the shunt detector be used?

Last Answer : When the input voltage variations are too small to give a usable output from a series detector.

Description : How does the current-diode detector differ from the voltage-diode detector?

Last Answer : The current-diode detector is in parallel with the input and load.

Description : What is the function of the diode in a series-diode detector?

Last Answer : Rectifies the rf pulses in the received signal.

Description : What does the simplest diode detector use to reproduce the modulating frequency?

Last Answer : The modulation envelope.

Description : What three functions does the transistor in a regenerative detector serve?

Last Answer : Oscillator, mixer, and detector.

Description : What simple, one-transistor detector circuit uses the heterodyne principle?

Last Answer : Regenerative detector.

Description : To measure incident power, you must rotate the coupler detector of the wattmeter so that the arrow indicating power flow points toward which end of the transmission line?

Last Answer : Load.

Description : When troubleshooting a magnetic controller, it is found that the contacts are welded together. The most probable cause is _____________. A. excessive operation at low load B. high ambient temperature C. low voltage on the operating coil D. high voltage on the operating coil

Last Answer : Answer: C

Description : Explain operation of balanced slope detector with „s‟ curve.

Last Answer : Diagram: Explanation:   Curve:  

Description : Draw & explain operation of phase detector.

Last Answer : In phase detector, the op-Amp basically acts as a zero crossing detector. If a sine wave is applied at the i/p, we get square wave at the op-Amp o/p (at point ... to two channel of the CRO. The time duration between the pulses corresponding to voltages represent the phase between them. 

Description : In an alternating current electrical system, a low system power factor is a direct sign of _____________. A. wasted energy B. efficient operation C. a short in the exciter field windings D. an excessive number of minor system grounds

Last Answer : Answer: A

Description : The main importance of ARM micro-processors is providing operation with ______ A. Low cost and low power consumption B. Higher degree of multi-tasking C. Lower error or glitches D. Efficient memory management

Last Answer : A. Low cost and low power consumption 

Description : LEDs operating at 850 nm provide sufficient optical power for short-distance, low-bandwidth multimode systems. List three conditions that prevent the use of LEDs in longer distance, higher bandwidth multimode systems.

Last Answer : Multimode fiber dispersion, the relatively high fiber attenuation, and the LED's relatively low optical output power.

Description : During its operation, loud buzzing and resultant welding of contacts of a magnetic relay may be caused by __________. A. overheating of the contactor coil B. low voltage on the operating coil C. low insulation resistance to ground D. lubrication of the contact bearing points

Last Answer : Answer: B