User:Pranav Rathi/Notebook/OT/2010/05/12/Characterization of AOM module

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 Revision as of 12:46, 15 November 2012 (view source) (→Normal mode operation characterization)← Previous diff Revision as of 13:06, 15 November 2012 (view source) (→Normal mode operation characterization)Next diff → Line 16: Line 16: ===Normal mode operation characterization=== ===Normal mode operation characterization=== - In normal mode, AOM is controlled through NI-DAQ by LabView program. Voltage input for RF signal is from 1 Volt to 5 Volts in any Volt increment. 1st order diffracted beam power is recorded for every ascending voltage increment of .1Volt for .5W, 1.5W, 2W and 2.5W input laser powers. Different laser powers are used to check if any how the characteristic of the AOM is input power dependent, which it should not be. RF signal Vs diffracted beam power will help us in obtaining the best workable range of voltages over which power increases linearly. I will also help us in characterizing the relationship between the voltage and diffracted power. The data is presented below: + In normal mode, AOM is controlled through NI-DAQ by LabView program. Voltage input for RF signal is from 1 Volt to 5 Volts in any Volt increment. 1st order diffracted beam power is recorded for every ascending voltage increment of .1Volt for .5W, 1.5W, 2W and 2.5W input laser powers. Different laser powers are used to check: If the characteristic of AOM is input power dependent, which it should not be. RF-input voltage Vs 1st order diffracted beam power will help us in obtaining the best workable range of voltages over which power increases linearly. It will also help us in characterizing the relationship between the voltage and diffracted power. This is very important in data analysis. While data acquisition we can not measure the laser power in trap its is unpractical but if know the characteristic RF-input voltage Vs laser power in trap we can calculate the laser power in trap from the voltage. The data is presented below: {{ShowGoogleExcel|id=0ApjWjFYiQdkfdDhNLXZOMUZwYXpONzhIU3V3MElicHc|width=800|height=600}} {{ShowGoogleExcel|id=0ApjWjFYiQdkfdDhNLXZOMUZwYXpONzhIU3V3MElicHc|width=800|height=600}}

AOM Characterization

Introduction:

The motive of this is to study AOM as power modulator for the tweezers. AOM (Gooch & Housego R23080-2-1.06-LTD; 138252) operates in CW and normal mode. We use 1st order diffracted beam. First CW mode operation is characterized, to know the usable power (of the diffracted beam) Vs ascending input laser power. Second normal mode operation is characterized: Computer controlled ascending input voltage for RF signal power Vs usable power of the diffracted beam, at several input laser powers. The laser temperature is kept constant at 62F.

Setup:

Relatively simple setup ThorLabs power meter is place infront of the diffracted beam from AOM. An aperture is used infront of the power meter to keep off all the stray beams.

CW mode operation characterization:

The AOM is operating in CW mode. Data is recorded; laser power (.25W to 4W in .25W increments) Vs 1st order beam power. This 1st order beam power is the usable power for tweezer. The data is presented below:

Result:

The relationship is linear. So the AOM gives output power in 1st order diffracted beam, of average around 70% of the input power (in CW mode). This help us calculating the usable power of any input power without measuring; for example if I set the laser on .10W, then the usable power at the tweezer is 70% of it, which is .07W or 70mW.The maximum usable power for the tweezer is 2.66W. If we want to stay in the single mode operation regime, it is 1.4W (at room temperature). When the laser is cooled down to 60F, it is stretched to 1.9W (2.75W input).

Normal mode operation characterization

In normal mode, AOM is controlled through NI-DAQ by LabView program. Voltage input for RF signal is from 1 Volt to 5 Volts in any Volt increment. 1st order diffracted beam power is recorded for every ascending voltage increment of .1Volt for .5W, 1.5W, 2W and 2.5W input laser powers. Different laser powers are used to check: If the characteristic of AOM is input power dependent, which it should not be. RF-input voltage Vs 1st order diffracted beam power will help us in obtaining the best workable range of voltages over which power increases linearly. It will also help us in characterizing the relationship between the voltage and diffracted power. This is very important in data analysis. While data acquisition we can not measure the laser power in trap its is unpractical but if know the characteristic RF-input voltage Vs laser power in trap we can calculate the laser power in trap from the voltage. The data is presented below: