1. INNOVATIVE OPTICAL PARAMETRIC SOURCES USING ISOTROPIC SEMICONDUCTORS E. Rosencher, M. Baudrier, R. Haidar,A. Godard, M. Lefebvre and Ph. Kupecek* ONERA * University PMC

2. Why bother? Semiconductor  (2) properties Quasi-phase matching Total internal reflection phase matching Random phase matching Self-difference frequency generation Conclusions SUMMARY

3. Why bother? Semiconductor  (2) properties Quasi-phase matching Total internal reflection phase matching Random phase matching Self-difference frequency generation Conclusions

4. Tunability Laser Diodes vs OPO 10 CRYOGENY Single diodesingle Pulsed OPO

5. Atmospheric transmission (dry weather, sea level, 5 km)

6. Why bother? Semiconductor  (2) properties Quasi-phase matching Total internal reflection phase matching Random phase matching Self-difference frequency generation Conclusions

7. SEMICONDUCTORS 0.45 µm < cutoff  < 20 µm (0.05 eV < E gap < 3 eV) Second Fermi Golden Rule Harmonic oscillator High nonlinear performance (quantum theory of solids) :   Large transparency region Mature technology III-V  LiNbO 3 46810121416182022 10 20 30 40 50 60 70 (µm) ZnSe GaAs Transmission including Fresnel losses (%) Isotropic materials  NO possible phase matching scenario  Low cost 

8. Propriétés optiques non linéaires des matériaux

9. First order quasi-phase matching I DFG  k.L +d -d  Cohérence

10. NbLiO 3 5000 V 10 kg/cm 2 Ferroelectric polling M. Fejer et al (Standord ) Molecular bonding (GaAs, ZnSe) TRT, ONERA, Stanford GaAs ZnSe ….. Quasi-phase matching techniques Fresnel birefrigence R. Haidar et al (ONERA ) Localized growth E. Lallier et al; M. Fejer et al Ge

11. Periodical materials breakthrough PPLN POGaAs 2 cm 40 µm f = 10 kHz 20 ns 98%

12. Precise coherence length (  C ) determination experimental set-up HgCdTe detector Filters Wedge 1.06 µm 11 LiNbO 3 OPO wavelength control  3 &  2 motorized translation Pulse Energy : 1mJ, 15ns  = 2 cm -1 I   1 – F x cos (  k.L) thickness  (a few deg.)

13. Advantage of large gap semiconductors in the IR: Large coherence length R. Haïdar, A. Mustelier, Ph. Kupecek, E. Rosencher, R. Triboulet, Ph. Lemasson and G. Mennerat, JAP 2002 Adashi Li

14. Why bother? Semiconductor  (2) properties Quasi-phase matching Total internal reflection phase matching Random phase matching Self-difference frequency generation Conclusions

15. Quasi Phase Matching by Total Internal Reflexion * (Fresnel Birefringence) * Armstrong et al., Phys. Rev. 127, 1918-1939 (1962) t L    F d up d down           tot  k.L  F   if d up. d down > 0  if d up. d down < 0  F =   -   -  

16. Angle tuning  tot  Fresnel phase matching z I Optimum thickness L  (2n+1)  c Dispersion phase matching z I L    Fresnel QPM

17. Haïdar et al., APL Fresnel QPM non resonant QPM resonant QPM

18. Resonant Fresnel angle allowing (1.9 µm, 2.3 µm)  8 µm Optimum angle for Fresnel birefringence phase matching Haïdar et al., JOSA B

19. Fresnel phase matching Configuration : experimental set-up HgCdTe detector Filters 1.06 µm LiNbO 3 OPO wavelength control  3 &  2 Pulse Energy : 1mJ, 15ns  = 2 cm -1 11 ZnSe plate R. Haïdar, A. Mustelier, Ph. Kupecek, E. Rosencher, R. Triboulet, Ph. Lemasson, APL 2002 10 mm ZnSe

20. Photonic yield : MIR Source :.1 µJ between 9 µm and 13 µm Pump  3 : 150 µJ Fresnel quasi-phase matching: GaAs

21. Limitations of Fresnel QPM: influence of wafer roughness ZnSeGaAs 114 27452545 9898.699.499.6

22. shift  x N max  200 Limitation to Fresnel QPM: Goos-Hänchen shift Equivalent to walk off

23. Why bother? Semiconductor  (2) properties Quasi-phase matching Total internal reflection phase matching Random phase matching Self-difference frequency generation Conclusions

24. Few lines of trivial theory Very predictive: - conversion yield proportional to sample length - independant on polarisation - resonant for - N/N eff easily measurable and compared with materials Non depletion approximation 3 processes independant with

25. RANDOM PHASE MATCHING Résonance pour taille de grain = longueur de cohérence 110 axis polycristalline Non linear diffusion in powder liquid and gas Phase mismatch (a) (b) Quasi-phase matching (c) (d) Baudrier, Haidar, Kupecek, Rosencher (Nature, 2004.)

26. Why bother? Semiconductor  (2) properties Quasi-phase matching Total internal reflection phase matching Random phase matching Self-difference frequency generation Conclusions

27. Cr 2+ -doped ZnSe 0.510 µm VB CB High optical cross-section High solubility Large bandwith Good ONL materials Good lasing materials Self OPO S T 2.1  2.3 µm Cr 2 + 1.9 µm Pompe: 1.9 µm Laser: 2.3 µm DFG-OPO: 10 µm ZnSe:Cr X WiFi collapse !

28. Self-DFG Cr:ZnSe laser—set-up 50% single-pass absorption of the 1.9-µm pump energy 45° internal phase-matching angle (spp), 13 internal reflections Simple design: easy alignments, but high losses 1.9 µm pump 2.4 µm laser 9 µm DFG Cr:ZnSe single-crystal (uncoated) OPO Nd:YAG 1.06 µm 10 ns 30 Hz Tmax @ 1.9 µm R = 95% @ 2.4 µm Rmax @ 1.9 µm R = 95% @ 2.4 µm Tmax @ 9 µm

29. Laser (2.4 µm) 5% yield (/absorbed energy) Small coupler transmission to maximize the 2.4-µm intracavity electric field Self-DFG Cr:ZnSe laser – first results First demonstration of self-DFG in Cr:ZnSe laser 9-µm DFG preliminary results Note: thresholdless emission !

30. Small temporal overlap of pump and laser pulses Limited DFG efficiency Solution: longer pulse pump source Emitted DFG spectrum Broad line (no intracavity spectral filter) Fixed central wavelength Possible tuning schemes: pump or laser tuning + crystal rotation Self-DFG Cr:ZnSe laser – discussions

31. Why bother? Semiconductor  (2) properties Quasi-phase matching Total internal reflection phase matching Random phase matching Self-difference frequency generation Conclusions

32. Isotropic semiconductors are becoming viable solutions for non linear optical sources in the mid-infrared Fresnel phase matching allows very large tunability from the mid-IR to the terahertz Cr 2 + doped ZnSe allows thresholdless self DFG generation which greatly simplify source architectures: first realisation presented! Surface roughness principal limitations to Fresnel QPM Next step: electrical pumping of OPO ! Random phase matching works in poly ZnSe and allows very large samples