optics

Mach-Zehnder Interferometry and Erasure of ‘Which-path’ Information

Student Manual

One of the most astounding and bewildering depictions of quantum mechanics is the single- particle interference experiment. If a source that emits only one particle (such as photons or electrons) at a time, is used in a classic double slit experiment, an interference patterns will emerge. This pattern is built up over multiple passes of identical particles. Interestingly, the pattern could be switched on and off even after light has emerged from the interferometer.

The Mach-Zehnder interferometer is a useful device for exploiting the wave nature of light and observing various aspects of interference. The goal of this experiment is to familiarize students with this kind of an interferometer. We will observe interference of light, and see conditions under which interference can be washed out, and ultimately recovered.

Sample Results Erasure and recovery of which-path information inside a Mach-Zehnder interferometer
Variation of intensity pattern with the post-interferometer polarizer
Variation of optical intensity with the relative angle between the polarizers placed inside the arms of the interferometer
Fringes change their visibility as polarizers between the arms of the interferometer change their relative angles
Experiment Code 2.21
Version 2018-v1

Further Readings and References


Pictorial Procedure

IMG_2499 (Medium)IMG_2501 (Medium)

IMG_2502 (Medium)IMG_2503 (Medium)

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Determining the Planck’s constant

Omair1An interesting use of the ubiquitous light bulb is its utility in determining a fundamental constant of quantum mechanics – namely the Planck constant. The purpose of Omair qazi’s experiment was to measure Planck’s constant through the observation of black body radiation. Spectral analysis of the light was carried out verifying Planck’s radiation laws, all using filtered light from a bulb, a spectrometer and photodetectors.

By Azeem Iqbal | Research Stories
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Tuning a Laser Diode

Student Manual

In this experiment we will develop an understanding of how a laser diode’s optical power and wavelength can be varied by controlling its temperature and operating current.

Software Code Download
Sample Results Optical Power Vs Injection Current
Wavelength Vs Temperature
Hardware Manual L785P100 Specification Sheet
Laser Diode Mount Manual
Laser Diode Driver Manual
Experiment Code 3.6
Version 3rd July 2014, 2014-v2

Further Readings and References


Pictorial Procedure

LaserModulationSetup1 LaserModulationSetup2 LaserModulationSetup3 LaserModulationSetup4

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Investigating Longitudinal Laser Modes using a Scanning Fabry-Perot Interferometer

Student Manual

The Fabry-Perot interferometer is an optical instrument which uses multiple-beam interference. In this experiment we will learn to characterize the interferometer and use it to diagnose the longitudinal modes of a HeNe laser.

Software Code Download
Sample Results Cavity Transmission Plot
Cavity output on oscilloscope
Effect of changing scan parameters on the observed longitudinal modes of a He-Ne laser
Simulating transmission from the Fabry Perot cavity
Hardware Manual Fabry-Perot Cavity Manual
Fabry-Perot Cavity Controller Manual
Experiment Code 3.5
Version 27 May 2014, 2014-v2

Further Readings and References

  • Introduction to Optics
    Pearson Education , F. L. Pedrotti, L. S. Pedrotti and L. M. Pedrotti Section 8.8 , (2008).

Pictorial Procedure

FP1 FP2v2 FPcavity

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Analyzing the Polarization State of Light through the Fourier Series

Student Manual

One can completely determine the polarization of light simply by using a polarizer and a quarter wave plate. In this experiment you will develop a method to generate as well as analyze different polarization states of light.

Experiment Code 3.4
Version 20 May 2014, 2014-v1

Further Readings and References


Pictorial Procedure

Polarization2setup

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Investigating Polarization of Light through Jones Calculus

Student Manual

Polarization is one of the fundamental properties of light. The purpose of this experiment is to get familiarized with the polarization of light as well as effects of different optical components on it.

Sample Results Polarized Beam Splitter
Quarter Wave Plate
Experiment Code 3.3
Version 20th May 2014, 2014-v1

Further Readings and References

  • Introduction to Optics
    Pearson Education , F. L. Pedrotti, L. S. Pedrotti and L. M. Pedrotti chapter 14 , (2008).

Pictorial Procedure

Polarization1setup1Polarization1setup2

DETAIL
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