(P441+P442) general operation of the lab and grading scheme:

Total credits: 8

General theme: Optics and condensed matter physics (open ended experiments)

Major emphasis: After three years of basic training on lab etiquettes, the 7th and 8th sem

labs put emphasis on systematic independent approach to laboratory experiments. This

means, whether student is designing a new experimental setup or working on an existing

setup, all aspects of the experiment should receive a critical look.

Existing experimental setups: 8 (listed below)

Design a new setup: Students are encouraged to propose feasible new experiments fitting

the general theme of the lab and design it themselves. Such experiments should be planned

keeping in mind the resources available within NISER. However, if needed, upto Rs 25000

can be spent by the department on designing such new experiments.

Time with each experiment: There will be no strict time limit for the individual

experiments. Overall, each group (of 2 people) is expected to finish at least 5 existing

experiments by the end of the semester. In case a group is involved in designing a new

experiment, a maximum of 6 weeks (half a semester!) will be allowed at a time.

Lab reports: In view of the overall feeling of higher semester students towards lab reports

and the history of lab report submissions, we want to experiment a slightly different

approach. Students have to choose one of the following two options.

Option 1: Submit a formal lab report within one week of each experiment. By any

standards, one week should be more than enough time to prepare a good lab report.

Option 2: Maintain a lab notebook which will be evaluated from time to time. In this option

I wont ask for a report unless there is something interesting in the results. Lab notebook

should be a dated record of your progress in the experiment. This can contain sketches

relevant to experiment, ideas, logical steps taken to overcome a problem, random

discussions on mechanisms and concepts involved, data taken during the experiment etc..

Just to make it clear, I am not expecting a line by line narration of everyday activities. What

is expected is, if someone checks the notebook he should get a feeling of what you did and

why you did. This is much more relaxing because, you just have to scribble things on the go,

while doing the experiment. Two people in the same group should have their own lab

notebook, with own scribbling.

Grading Scheme: Cumulative Daily Evaluation (independent approach and effort): 40 % Lab notebook OR lab reports: 20% Final exam and/or presentation: 40 %

List of experiments:

Existing setups:

1. Study of Interference, diffraction and polarization using microwaves

2. Alignment of He-Ne laser and study of spectral and spatial properties of the beam

3. Laser-Doppler anemometry

4. Electro-optic Kerr effect

5. Study of multimode and single mode optical fibers using diode and He-Ne laser

6. Magneto-striction using Michelson interferometry

7. Dielectric constant at microwave frequency

8. Study of lock-in amplifier

9. Study of solar cells

Suggested new experiments we can discuss about these and/or you can come up

with more ideas

10. Design an experiment to plot acoustic dispersion relation (ref: Am. J. Phys.)

11. Design an experiment to study tunneling of vibrational modes in spring mass system

(is it even possible?)

12. Develop a setup for measurement of conductance quantization in a point contact

(Ref. Am. J. Phys.)

13. Develop a setup for inductive measurement of critical temperature of

superconductors using LC tank circuit (Meissner effect)

Tentative objectives of the experiments:

1. Study of interference, diffraction and polarization using microwaves

Objectives: (i) measurement of radiation pattern of microwave source in space (ii)

Collimating a beam at microwave frequency (iii) Diffraction pattern of a single slit

and determination of microwave frequency (iv) interference pattern in a Michelson

interferometer and determination of microwave frequency (v) Interference pattern

in Fabry-Perot interferometer and determination of microwave frequency (vi) study

polarization of EM waves at microwave frequency.

2. Alignment of He-Ne laser and study of spectral and spatial properties of the beam

Objectives: (i) Alignment of green tracking laser (ii) Alignment of He-Ne laser tube

and resonator mirrors using the green tracking laser (iii) Realization of lasing action

(iv)Measurement of beam diameter, laser wavelength, and state of polarization of

the laser output.

3. Laser-Doppler anemometry

Objectives: (i) Setting up of the optical components and adjusting the beam

intersection point (ii) Check for interference pattern in the region where the sample

is to be placed (iii) Adjust the quartz-cell at the intersection and set the photo-

detector to observe the intensity variation due to Doppler shift in the two laser

beams (iv) Calculate the particle flow velocity.

4. Elecetro-optic Kerr effect

Objectives: (i) Align the optics on the bench for dc electro-optic Kerr effect (ii)

Measure rotation of polarization of the He-Ne laser as a function of applied electric

field on the PLZT crystal (iii) Calculate the Kerr coefficient of the PLZT crystal (iv)

Add an ac modulation on the dc voltage and study the response of the crystal to the

ac field.

5. Study of multimode and single mode optical fibers using diode and He-Ne laser

Objectives: (i) Coupling laser beam (He-Ne and diode laser) in a multi-mode optical

fiber (ii) Maximizing the coupling and measurement of throughput power (using

both diode laser and He-Ne laser) in multi-mode fiber (iii) Measurement of

numerical aperture of multi-mode fiber (both using diode laser and He-Ne Laser)

(iv) Measurement of length of a multi-mode fiber (in the spool) by employing

frequency modulation of diode laser and ascertaining the time-delay (v)

Measurement of absorption loss in a multi-mode fiber using He-Ne laser (vi)

Alignment of He-Ne laser for coupling light into single-mode optical fiber (vii)

Coupling He-Ne laser beam in single-mode optical fiber and maximizing the power

throughput in single-mode fiber (viii) Measurement of numerical aperture of single-

mode fiber (ix) Measurement of mode-field diameter of single-mode fiber.

6. Magneto-striction using Michelson interferometry

Objectives: (i) Set up the optics in Michelsons interferometer geometry with one of

the mirrors mounted on the magnetic shaft and align for interference pattern (ii)

Apply magnetic field to the magnetic shaft via the solenoid and calculate magneto-

striction from the fringe shift (iii) Plot mgneto-striction as a function of magnetic

field for various materials.

7. Dielectric constant at microwave frequency

Objectives: (i) Arrange the waveguide, the Klystron (what is it?), and the detector

correctly in order to optimize the output signal in one range of the voltmeter (ii)

Determine the microwave frequency from the measurement of standing wave

pattern in the waveguide (iii) Study the changes in the standing wave pattern due to

reflection at various insulating plates (iii) Calculate dielectric constant of Teflon,

Ebonite, Wax, and Perspex.

8. Study of lock-in amplifier

Objectives: (i) Get acquainted with various stages of a lock-in amplifier, study the

characteristics of the pre-amplifier, filters and the detectors (ii) Use a Wheatstone

bridge arrangement in conjunction with the lock-in detector to measure a small

resistance (iii) Study how noise signal affects the lock-in output by analyzing a

known signal mixed with the signal from a noise source (iv) Think and implement

the lock-in detector in a real experiment.

9. Solar cells.

Objectives: (i) Study the characteristics of the provided Si solar cell by measuring

the current-voltage curves under different illuminations (sunlight, filament lamp

etc.). (ii) Study frequency response using the available color filters (iii) Study a

home-made Dye-sensitized solar cell in the similar manner and compare the

effective efficiencies in the two cases (iii) Explore how the two types of solar cells

work and discuss the similarities and limitations in the two cases. Optional: Make

your own Dye-sensitized solar cell and find its efficiency.

Develop a setup for measurement of conductance quantization in quantum point

contacts

Objectives: (i) prepare a mechanical setup to make intermittent contact between

two thin wires and set a voltage divider circuit to apply a voltage to the point

contact (ii) Design an op-Amp current-voltage converter to feed the changing

current in the contact to an oscilloscope (and may be from oscilloscope to a PC

by a program) (iii) Look for conductance steps and find the quantization value

for various conductors (Copper, Aluminum, Steel, and Gold)

Develop a setup for inductive measurement of critical temperature of

superconductors using LC tank circuit using Meissner effect.

Objectives: (i) Design an oscillator circuit consisting a LC tank resonator with a

air-core inductor (ii) Feed the output to on oscilloscope and develop a simple

program for continuous reading of the oscillation frequency from the

oscilloscope to the PC (iii) Arrange a mechanism to place a superconducting

sample inside the inductor coil and cool it to liquid nitrogen temperature (iv)

Record the change in resonant frequency as a function of temperature to find the

superconducting transition temperature of the sample.