Photonics Flashcards
What is optical time-domain reflectometry?
It’s a technique used to characterize an optical fiber. It injects optical pulses into a fiber and extracts light (from the same end) light that has been Rayleigh backscattered or reflected at certain points. (Distance determined by time delay of backscatter). Can measure splice loss.
What’s the thermoelectric effect?
It is what allows a thermoelectric cooler to function. Consists of Seebeck and Peltier effects. Seebeck effect is EMF that develops across two points of an electrically conducting material when tehre is a temperature difference; there’s a hot and cold end
What is a transimpedance amplifier circuits?
They are commonly used in photodetectors, and convert current to voltage. The current to voltage gain is set by the resistance of a feedback resistor (“R1”). Commonly 100K Ohms.
How to characterize photodetector wavelength performance?
Responsivity is a frequency dependent value that’s a function of photocurrent and optical power. This is the value you can measure.
What is a 3dB coupler?
It splits an input signal into two equal amplitude outputs.
What are arrayed waveguide gratings?
They are integrated optics that demultiplex broadband light into individual wavelength contributions by inducing a distribution of phase shifts as the light propagates through multiple waveguides of different length. Can be used as spectrometers in OCT on a chip.
What sort of materials are integrated photonic waveguides made out of?
Silicon nitride, gallium arsenide
