INNOVATIVE OPTICAL PARAMETRIC SOURCES USING ISOTROPIC SEMICONDUCTORS E

SUMMARY • Why bother? • Semiconductor c(2) properties • Quasi-phase matching • Total internal

• Why bother? • Semiconductor c(2) properties • Quasi-phase matching • Total internal

Laser Diodes vs OPO 10 Tunability single Pulsed OPO CRYOGENY Single diode

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

SEMICONDUCTORS • 0. 45 µm < lcutoff < 20 µm (0. 05 e. V

Propriétés optiques non linéaires des matériaux

First order quasi-phase matching +d -d I DFG D k. L LCohérence

Quasi-phase matching techniques 10 kg/cm 2 5000 V Nb. Li. O 3 Ferroelectric polling

Periodical materials breakthrough 2 cm f = 10 k. Hz 20 ns 40 µm

Precise coherence length (LC) determination experimental set-up wavelength control • Pulse Energy : 1

Advantage of large gap semiconductors in the IR: Large coherence length Li Adashi R.

Quasi Phase Matching by Total Internal Reflexion * (Fresnel Birefringence) w 2 (p) •

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

Optimum angle for Fresnel birefringence phase matching Resonant Fresnel angle allowing (1. 9 µm,

Fresnel phase matching Configuration : experimental set-up wavelength control • Pulse Energy : 1

Fresnel quasi-phase matching: Ga. As Pump w 3 : 150 µJ MIR Source :

Limitations of Fresnel QPM: influence of wafer roughness Zn. Se Ga. As 11 4

Limitation to Fresnel QPM: Goos-Hänchen shift Dx Nmax 200 Equivalent to walk off

Few lines of trivial theory Non depletion approximation 3 processes independant with Very predictive:

RANDOM PHASE MATCHING (c) (a) Quasi-phase matching Phase mismatch Baudrier, Haidar, Kupecek, Rosencher (Nature,

Cr 2+-doped Zn. Se CB 0. 510 µm Cr 2 + T Wi. Fi

Self-DFG Cr: Zn. Se laser—set-up Rmax @ 1. 9 µm R = 95% @

Self-DFG Cr: Zn. Se laser – first results Laser (2. 4 µm) 9 -µm

Self-DFG Cr: Zn. Se laser – discussions Small temporal overlap of pump and laser

Conclusions • Isotropic semiconductors are becoming viable solutions for non linear optical sources in

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

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

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

Laser Diodes vs OPO 10 Tunability single Pulsed OPO CRYOGENY Single diode

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

SEMICONDUCTORS • 0. 45 µm < lcutoff < 20 µm (0. 05 e. V < Egap < 3 e. V) • High nonlinear performance (quantum theory of solids) : Second Fermi Golden Rule • Large transparency region Transmission. Harmonic including Fresnel losses (%) oscillator 70 • Low cost Zn. Se 60 50 40 • Mature technology III-V Ga. As 30 20 10 4 6 8 10 12 14 l (µm) • Isotropic materials NO possible phase matching scenario Li. Nb. O 3 16 18 20 22

Propriétés optiques non linéaires des matériaux

First order quasi-phase matching +d -d I DFG D k. L LCohérence

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

Periodical materials breakthrough 2 cm f = 10 k. Hz 20 ns 40 µm 98% PPLN POGa. As

Precise coherence length (LC) determination experimental set-up wavelength control • Pulse Energy : 1 m. J , 15 ns • Ds = 2 cm-1 1. 06 µm Li. Nb. O 3 OPO Iw 1 1 – Fx cos (Dk. L) w 3 & w 2 motorized translation Wedge a (a few deg. ) w 1 Filters Hg. Cd. Te detector thickness

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

Quasi Phase Matching by Total Internal Reflexion * (Fresnel Birefringence) w 2 (p) • w 3 (s) dup + FF ddown L t q w 1(p) dftot = Dk. L + FF + 0 if dup. ddown > 0 p if dup. ddown < 0 FF = f 3, s - f 2, p - f 1, p *Armstrong et al. , Phys. Rev. 127, 1918 -1939 (1962)

w 2 Fresnel QPM w 3 L w 1 I z L = (2 n+1) Lc Dispersion phase matching Optimum thickness I z dftot = 0 [2 p] Fresnel phase matching Angle tuning

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

Optimum angle for Fresnel birefringence phase matching Resonant Fresnel angle allowing (1. 9 µm, 2. 3 µm) 8 µm Haïdar et al. , JOSA B

Fresnel phase matching Configuration : experimental set-up wavelength control • Pulse Energy : 1 m. J , 15 ns • Ds = 2 cm-1 1. 06 µm Li. Nb. O 3 OPO w 3 & w 2 10 mm Zn. Se plate w 1 Zn. Se Filters Hg. Cd. Te detector R. Haïdar, A. Mustelier, Ph. Kupecek, E. Rosencher, R. Triboulet, Ph. Lemasson, APL 2002

Fresnel quasi-phase matching: Ga. As Pump w 3 : 150 µJ MIR Source : . 1 µJ between 9 µm and 13 µm Photonic yield :

Limitations of Fresnel QPM: influence of wafer roughness Zn. Se Ga. As 11 4 27 45 25 45 98 98. 99. 6 4 6

Limitation to Fresnel QPM: Goos-Hänchen shift Dx Nmax 200 Equivalent to walk off

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

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

Cr 2+-doped Zn. Se CB 0. 510 µm Cr 2 + T Wi. Fi collapse ! 2. 1 2. 3 µm S VB 1. 9 µm High optical cross-section High solubility Large bandwith Good ONL materials Pompe: 1. 9 µm Good lasing Laser: 2. 3 µm Self DFG-OPO: 10 µm materials Zn. Se: Cr X OPO

Self-DFG Cr: Zn. Se laser—set-up Rmax @ 1. 9 µm R = 95% @ 2. 4 µm Tmax @ 9 µm Nd: YAG 1. 06 µm 10 ns 30 Hz 2. 4 µm laser 9 µm DFG 1. 9 µm pump OPO Cr: Zn. Se single-crystal (uncoated) Tmax @ 1. 9 µm R = 95% @ 2. 4 µm 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

Self-DFG Cr: Zn. Se laser – first results Laser (2. 4 µm) 9 -µm DFG preliminary results 5% yield (/absorbed energy) Note: thresholdless emission ! Small coupler transmission to maximize the 2. 4 -µm intracavity electric field First demonstration of self-DFG in Cr: Zn. Se laser

Self-DFG Cr: Zn. Se laser – discussions 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

Conclusions • 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 • Surface roughness principal limitations to Fresnel QPM • Random phase matching works in poly Zn. Se and allows very large samples • Cr 2+ doped Zn. Se allows thresholdless self DFG generation which greatly simplify source architectures: first realisation presented! Next step: electrical pumping of OPO !