Mode Matching Resonator 2 - plan and curve mirror

Mirror configuration

Parameter

Radius of curvature of mirror R1: R1= 500 mm

Radius of curvature of mirror R2: R2= infinity (Incoupling side)

Wavelength: λ= 916.0 nm

Length between the resonator mirrors: L= 100 mm

Beam radius at cavity-waist: w0=w2

Beam radius at mirror: w1, w2

Distance between:

mirror R1 and mirror R2: L

mirror R2/lense 1 and lense 2: X

lense 2 focal length: Z

mirror R2/lense 1 and collimatorlense: Y

collimatorlense and fiber: 4 mm

We used the programm Strahl.exe (@IQ)
Step 0: Choose parameter

Wellenlänge: 916 nm

Brechungsindex: 1 (Air)

Welcher Resonatortyp: linearer Resonator

Step 1: Beam waist calculation from resonator

Insert

Nr. 1: Spiegel 1 with Krümmungsradius 500mm → Brennweite: 250mm; Einfallwinkel: 0

Nr. 2: Abstand 100 mm

Nr. 3: Spiegel 2 with Brennweite 10000000000000 mm (so groß es ging)

Alternative: Planspiegel; Einfallwinkel: 0

→ Waistradius: w2= 270 µm, w1= 241.5 µm
→ FSR = 1.499 GHz

Step 2:

Change with “Change” Spiegel 2 to Linse 1 - Radius Spiegel verw?=ja y

Brechungsindex: 1.5

Brennweite: -400000000000000 mm

The values of the Waistradius and Strahlradius must not change!!!

<fc #ff00ff>Fenster?\\</fc>

Abstand S2 zu “Grenzfläche” Fenster

Grenzfläche: Brechungsindex 1.5 Einfallsw=0 Radius=0 bei unendl

Abstand dicke Fenster: 6.35mm

Grenzfläche: Brechungsindex 0 Einfallsw=0 Radius=0 bei unendl

Programm berechnet hieraus Strahlrad.-1ym (Nicht realistisch)

2. Ansatz

Berechnung der opt.Dichte → Weglängenänderung → Korrektur Abstand Spiegel zu Linse (wird größer) D(λ)=log[1-e^(-αλ)]=9,45mm → neuer Abstand X+3,15mm

Step 3:

Nr. 4: Abstand with Variable X <fc #ff00ff>ausgemessen 530mm</fc>

Nr. 5: Linse 2 with Variable Z (<fc #ff00ff>500mm=f</fc>)

Nr. 6: Abstand Y - X

Nr. 7: Linse 3 with Brennweite 4 mm (?)

Nr. 8: Abstand 4 mm

“Zielwaist” (Strahlrad.an Faserausgang): 5.2 µm

Step 4: Playing with the parameters X, Y and Z for the best Überlapp

with “Variable”

Lense focal length of Lense 2 Z [mm]	400	300	250	200	175	150	100	50
Distance between mirror R2 and lense 2 X [mm]	86	100	65	100	100	104	124	99
Distance between mirror R2 and collimator Y [mm]	210	272	230	250	245	240	216	141
Überlapp [%]	98.1	99.6	99.8	98.3	95.8	91.5	73.3	41.3