File:Simulated PDH readout.svg
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DescriptionSimulated PDH readout.svg |
English: Simulated plots of the reflection transfer function (magnitude and phase) of a two-mirror Fabry-Perot cavity, as well as a simulated PDH signal.
For the cavity mirrors I chose amplitude reflectivities of r1 = 0.99 and r2 = 0.98, and a length L = 1 m. For the modulation frequency I chose fm = 23 MHz (not 25 MHz as written in upload log). Matplotlib code is as follows: from matplotlib import plt import numpy as np c = 3e8 L = 1. fsr = c/(2*L) f = np.arange(-.4*fsr,.4*fsr,fsr/1e4) r1 = .99 r2 = .98 t1 = (1-r1**2)**.5 R = (r1-(r1**2+t1**2)*r2*np.e**(2j*2*np.pi*f*L/c))/(1-r1*r2*np.e**(2j*2*np.pi*f*L/c)) fm = 23e6 Rffm = (r1-(r1**2+t1**2)*r2*np.e**(2j*2*np.pi*(f+fm)*L/c))/(1-r1*r2*np.e**(2j*2*np.pi*(f+fm)*L/c)) Rfnfm = (r1-(r1**2+t1**2)*r2*np.e**(2j*2*np.pi*(f-fm)*L/c))/(1-r1*r2*np.e**(2j*2*np.pi*(f-fm)*L/c)) pdh = R*np.conjugate(Rffm)-np.conjugate(R)*Rfnfm plt.subplot(311) plt.plot(f/1e6,100*np.abs(R)**2,'#880088') plt.axis([-.4*fsr/1e6,.4*fsr/1e6,0,102]) plt.ylabel('Reflected power (\%)') plt.subplot(312) plt.plot(f/1e6,180*np.angle(R)/np.pi,'#880088') plt.axis([-.4*fsr/1e6,.4*fsr/1e6,-35,35]) plt.ylabel('Reflected phase (deg.)') plt.subplot(313) plt.plot(f/1e6,np.imag(pdh),'#880088') plt.ylabel('PDH readout (arb.)') plt.xlabel('$f-f_\mathrm{res}$ (MHz)') |
Date | |
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Own work This plot was created with Matplotlib. |
Author | Zueignung |
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Date/Time | Thumbnail | Dimensions | User | Comment | |
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current | 05:25, 12 August 2012 | 688 × 743 (76 KB) | Zueignung (talk | contribs) | xscale | |
17:32, 11 August 2012 | 720 × 681 (72 KB) | Zueignung (talk | contribs) | Percent fix | ||
06:41, 11 August 2012 | 721 × 724 (73 KB) | Zueignung (talk | contribs) | Redid simulation with more realistic values, and changed from omega to f. Two-mirror Fabry-Perot cavity, 1 m length. Amplitude reflectivities r_1 = 0.99 and r_2 = 0.98. PDH modulation frequency f_m = 25 MHz. | ||
06:17, 11 August 2012 | 719 × 711 (71 KB) | Zueignung (talk | contribs) |
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