40m QIL Cryo_Lab CTN SUS_Lab TCS_Lab OMC_Lab CRIME_Lab FEA ENG_Labs OptContFac Mariner WBEEShop
  40m Log  Not logged in ELOG logo
 List  |  Find  |  Login  |  Help 
Entry  Wed Apr 21 10:09:23 2010, kiwamu, Update, Green Locking, waist positon of Gaussian beam in PPKTP crystals focal_positin_edit.png
    Reply  Tue Apr 27 14:18:53 2010, kiwamu, Update, Green Locking, waist positon of Gaussian beam in PPKTP crystals mode_in_PPKTP.png
       Reply  Thu Jul 29 21:13:39 2010, Dmass, Update, Green Locking, waist positon of Gaussian beam in PPKTP crystals 
          Reply  Thu Jul 29 22:58:25 2010, kiwamu, Update, Green Locking, waist positon of Gaussian beam in PPKTP crystals 
             Reply  Fri Jul 30 00:02:15 2010, Dmass, Update, Green Locking, waist positon of Gaussian beam in PPKTP crystals 
                Reply  Fri Jul 30 09:51:58 2010, kiwamu, Update, Green Locking, Re: waist positon of Gaussian beam in PPKTP crystals efficiency_waist_edit.pngPPKTPmode.pngPSL_doubling.pngmode_in_PPKTP.png
Message ID: 3328     Entry time: Fri Jul 30 00:02:15 2010     In reply to: 3327     Reply to this: 3330
Author: Dmass 
Type: Update 
Category: Green Locking 
Subject: waist positon of Gaussian beam in PPKTP crystals 

Quote:

- As you said, I just calculated the waist position in the crystal because the speed of light changes in a medium and eventually the waist position also changes.

- Yes, I did. Once you get a beam with the right waist size, you just put your crystal at the waist position with the offset.

  In fact you don't have to think about the rayleigh range inside of the crystal because what we care is the waist size and it doesn't change.

Quote:

 If I understand your elog, you are just calculating the the offset in position space that you get by having a refractive index.

Did you end up changing the mode matching so that the rayleigh range (which changes with refractive index) was confocally focused inside the crystal (e.g. Zr = 15 mm?

 I thought we cared about satisfying the confocal focusing parameter, that is to say we want to set Zr = 2L_crystal. If Zr changes inside the crystal, this is the number we care about..isn't it NOT the waist size, but the rayleigh range we care about? I am not entirely sure what youre response is saying you did...

  1. Calculate Zr = pi * wo^2/(lamba/n)
  2. Do mode matching to get this wo in free space
  3. Calculate the offset you need to move the oven by using n
  4. Move hte ovens

OR

  1. Calculate Zr = pi*wo^2/(lamba)
  2. Do mode matching to get this in free space
  3. Calculate the offset you need to move your ovens using n
  4. Move your ovens

I guess the waist size would also let me know - are you using 69 um or 53 um waist size?

ELOG V3.1.3-