TY  - JOUR
A1  - Schüller-Ruhl, Aaron
A1  - Dinstühler, Leonard
A1  - Senger, Thorsten
A1  - Bergfeld, Stefan
A1  - Ingenhag, Christian
A1  - Fleischhaker, Robert
ED  - Mackenzie, Jacob
T1  - Direct fabrication of arbitrary phase masks in optical glass via ultra-short pulsed laser writing of refractive index modifications
JF  - Applied Physics B
N2  - We study the possibility to fabricate an arbitrary phase mask in a one-step laser-writing process inside the volume of an optical glass substrate. We derive the phase mask from a Gerchberg–Saxton-type algorithm as an array and create each individual phase shift using a refractive index modification of variable axial length. We realize the variable axial length by superimposing refractive index modifications induced by an ultra-short pulsed laser at different focusing depth. Each single modification is created by applying 1000 pulses with 15 μJ pulse energy at 100 kHz to a fixed spot of 25 μm diameter and the focus is then shifted axially in steps of 10 μm. With several proof-of-principle examples, we show the feasibility of our method. In particular, we identify the induced refractive index change to about a value of Δn=1.5⋅10−3. We also determine our current limitations by calculating the overlap in the form of a scalar product and we discuss possible future improvements.
Y1  - 2022
U6  - http://dx.doi.org/10.1007/s00340-022-07928-2
SN  - 1432-0649 (Online)
SN  - 0946-2171 (Print)
N1  - Corresponding author: Robert Fleischhaker
VL  - 128
IS  - Article number: 208
SP  - 1
EP  - 11
PB  - Springer
CY  - Berlin
ER  -