1. Self-injection linear polarization locking of a fiber laser
Christoph Bacher
Alexander Heidt
Valerio Romano
Manuel Ryser

2. Introduction and motivation
Linear polarized sources are essential for a wide range of applications: SHG, SFG, …
Not trivial for “non-standard” (1140 – 1160 nm) wavelength Yb-doped fiber lasers
Intra-cavity polarization filtering
Low efficiency
Upcoming parasitic ASE
PPLN ω 2ω

3. Related publications
Injection locking is used in a large variety of applications
Wavelength stabilization of laser diodes
Ventrudo, B. F. et al. “Wavelength and intensity stabilisation of 980 nm diode lasers coupled to fibre bragg gratings”
Pliska, T. et al. “Wavelength stabilized 980 nm uncooled pump laser modulesfor erbium-doped fiber amplifiers”
Achtenhagen, M. et al. “L-i characteristics of fiber bragg grating stabilized 980-nm pump lasers”
Polarization locking of He-Ne laser
Cotteverte, J. C. et al. “Polarization dragging in injected lasers”
Polarization locking of fiber distributed feedback (DFB) laser
Yamashita, S. et al. “Single-polarization operation of fiber distributed feedback (dfb) lasers by injection locking”
Hsu, K. et al. “Single-polarization generation in fiber fabry-perot laser by self-injection locking in short feedback cavity”

4. Setup
Bacher, C. et al., “Yellow light generation by frequency doubling of a fiber oscillator” (2016).

5. Measurement setup

6. Polarization extinction ratio
Signal output power: 2.5 W
Error bars ≙ SEM
Error bars ≙ 1σ STD

7. Polarization extinction ratio
Error bars ≙ SEM
Error bars ≙ 1σ STD

8. Proof-of-principle
Misalignment of HR FBG at port P3

9. Evolution of optical spectrum @ 1154 nm
Bandwidth: dB (OSA Resolution: 0.02 nm)

10. Evolution of optical spectrum
Note: 1154 nm is attenuated by the HR FBG at port P3
No forward propagating ASE up to 18.8 Watt pump power
No Raman scattering

11. Evolution of backward propagating signal
N.B. axis are in linear scale Backward propagating ASE visible at pump power of 18.8 Watt

12. Conclusion
Successfully demonstrated self-injection polarization locking of a fiber laser
Polarization extinction ratio of more than 500:1
Output of 2.5 Watt
Operation wavelength at edge of gain 1154 nm
No forward propagating ASE
Negligible backward propagating ASE
Outlook
Loss of polarization locking above 19 Watt pump power
Test of other couplers, e.g. 20/80
Test of other OC FBG

13. Acknowledgment The fiber group at IAP
Thomas Feurer Jonas Scheuner Christoph Lätt as well as Sönke Pilz, Ali El Sayed, Sheida Mahmoodi and Jos Kohn

14. Thank you for your attention
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