Answers

The basic questions of children's topics are answered in this page.

Electronic devices

BNC vs SMA

BNC is connector suitable for low power and frequency range of 0 to 4GHz but SMA is often used in much smaller cable connection and frequency range is larger up to 18GHz.

AC, CV, CC

AC is kind of current oscillating back and forth so is voltage but CV and CC are different which could be viewed as zero-frequency AC.

Oscilloscope

amplitude, frequency, coupling, trigger.amplitude represents voltage of signal,which can be adjusted by vertical button and frequency is shown and adjusted through horizontal button. trigger control is used for stabilizing the waveforms.two types of coupling are offered in the scope, AC and DC coupling.AC blocks DC signal but DC coupling allows the existence of two types of signals.

Signal generator

waveforms, frequencies, amplitudes, purposes, prices, possible substitutions

Spectrum Analyzer

on y axis, magnitude of signal are shown and frequency of signal is given on x axis. RBW determines the smallest signal frequency that can be resolved.(could be viewed as the eye of spectrum analyzer). as for VBW, it is like the smoothing of signals displayed on scope, lower the VBW is, more smooth the signals are displayed on scope. it is just reducing the amplitude of noise generated by detector.

Electronics

• opamps

it is a kind of amplifier which could produce the output hundreds even thousands times larger than the voltage difference between two inputs.

Basic optical elements

• BS or PBS (which polarization is reflected which is transmitted?)

PBS is polarizing beam splitter which could reflect beam of vertical polarization and transmit beam of horizontal polarization.

• HWP or QWP
• AOM

AOM is a sort of modulator that could produce output beams with different frequencies ,while being imposed acoustic wave with a certain frequency and input beam.

• Piezo-actuator

This actuator is able to shrink and expand, changing its length while voltage is applied to it.

• photodetectors

when you shine the light beam into its photo-diode, there is a voltage output corresponding to its input intensity， which could be seen on scope.

• Do not work in degenerate regime

Optical schemes

• telescope
• telescope with 3 lenses, focal distances sensitivity, why do we need it?
• mode cleaning
• beam angle adjustment (near and far field)
• mode matching of 2 beams
• homodyne detector alignment
• cavity alignment

Alkali metals

• Rubidium 87 level structure
• What is Failed to parse (Missing <code>texvc</code> executable. Please see math/README to configure.): 5^2P_{1/2}

Cold atoms

• Doppler effect
• Cooling force
• Why is it called molasses
• Why do we need magnetic coils?
• Doppler cooling limit