import numpy as np
def finesse(rf,re):#Finesse of Fabry–Perot cavity
    finesse_return=(np.pi*np.sqrt(rf*re))/(1-(rf*re)) 
    return finesse_return

def power_trans(rf,re,tf,te):#trans power of Fabry–Perot cavity
    phi=2*np.pi*1#phase when the cavity is in resonance.
    F=4*rf*re/(1-re*rf)**2
    Pt=(te*tf)**2/(1-re*rf)**2*(1/(1+F*np.sin(phi/2)))#trans power when the cavity is in resonance.
    return Pt

lossf_150=150e-6#Xarm front mirror Loss
losse_150=150e-6#Xarm end mirror Loss
lossf_45=45e-6#Xarm front mirror Loss
losse_45=45e-6#Xarm end mirror Loss
Te=5e-6 #Xarm end mirror Transmission ratio
Tf=0.004 #Xarm front mirror Transmission ratio
te=np.sqrt(5e-6) #Xarm end mirror Transmission ratio
tf=np.sqrt(0.004) #Xarm front mirror Transmission ratio

rf_150=np.sqrt(1-Tf-lossf_150) #Xarm front mirror Reflectance ratio(Loss of mirror is 150ppm)
re_150=np.sqrt(1-Te-losse_150)#Xarm front mirror Reflectance ratio(Loss of mirror is 150ppm)
rf_45=np.sqrt(1-Tf-lossf_45) #Xarm front mirror Reflectance ratio (loss of mirror is 45ppm)
re_45=np.sqrt(1-Te-losse_45)#Xarm front mirror Reflectance ratio (loss of mirror is 45ppm)

print('Finesse (Loss of mirror is 45ppm) : ',finesse(rf_45,re_45))###1531.28
print('Finesse(Loss of mirror is 150ppm) : ',finesse(rf_150,re_150))###1456.58


input_power=3 #Input power[W]
bs_half=1/2 #trans ratio of BS
#https://gwdoc.icrr.u-tokyo.ac.jp/DocDB/0077/P1807768/001/theses_morozumi_final.pdf
pre_trans=0.1#trans ratio of PRE
print('TRANS POWER(Loss of mirror is 45ppm) : ',input_power*pre_trans*bs_half*power_trans(rf_45,re_45,tf,te))###714uW
print('TRANS POWER(Loss of mirror is 150ppm) : ',input_power*pre_trans*bs_half*power_trans(rf_150,re_150,tf,te))###646uW

def power_refl(rf,re,tf,te):#Xarm power reflection ratio
    phi=2*np.pi
    F=4*rf*re/(1-re*rf)**2
    refl=(((tf**2+rf**2)*re-rf)**2+4*re*rf*(tf**2+rf**2)*(np.sin(phi/2))**2)/((1-rf*re)**2*(1+F*(np.sin(phi/2))**2))
    return refl
print("Xarm power reflection ratio:",power_refl(rf_45,re_45,tf,te))##0.909
print("Xarm power:",input_power*pre_trans*half*power_refl(rf_45,re_45,tf,te))#0.136
print('REFL port POWER(Loss of mirror is 45ppm) : ',input_power*pre_trans*bs_half*power_refl(rf_45,re_45,tf,te)*bs_half*pre_trans*bs_half*0.1*1e3,"mW")###0.34mW
print('REFL port POWER(Loss of mirror is 150ppm) : ',input_power*pre_trans*bs_half*power_refl(rf_150,re_150,tf,te)*bs_half*pre_trans*bs_half*0.1*1e3,"mW")### 0.27mW