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Multiple Processes Optical Parametric Oscillator

Multiple Processes Optical Parametric Oscillator. QNLO Summer School August 2010. Gil Porat Ady Arie’s group, Tel Aviv University, Israel. Outline. Introduction to c (2) NLO and QPM Introduction to OPO Multiple processes OPO implemantations

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Multiple Processes Optical Parametric Oscillator

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  1. Multiple Processes Optical Parametric Oscillator QNLO Summer SchoolAugust 2010 Gil Porat Ady Arie’s group, Tel Aviv University, Israel

  2. Outline • Introduction to c(2) NLO and QPM • Introduction to OPO • Multiple processes OPO implemantations • Efficient frequency down conversion to the mid IR • Tunable and efficient frequency up conversion • Summary and future prospects

  3. Introduction to c(2) NLO and QPM • The material is dispersive • Each frequency has a different phase velocity which also depends on temperature (phase mismatch) w1+w2 Sum frequency generation (SFG) w1- w2 Difference frequency generation (DFG)

  4. Introduction to c(2) NLO and QPM • Quasi phase-matching • The modulation period is tailored for one specific process (a particular set of w1, w2 and w3 at a certain temperature).

  5. ws wp wi Introduction to Optical Parametric Oscillator • A DFG crystalin a resonator pumped by a laser wp. • The two other DFG frequencies are named signal and idler. The signal is resonant. • The signal and idler are initially created spontaneously. Since the signal is resonant, the stimulated DFG process quickly picks up. • Temperature change ® phase-mismatch change ® signal and idler frequencies change ws ws ws wp wi OPO: wi=wp-ws Pump ® Signal & Idler

  6. idler idler pump signal signal2 Efficient Down Conversion to the Mid-Infrared G. Porat, O. Gayer and A. Arie, Optics Letters 35, 1401 (2010)

  7. Simultaneous OPO and DFG • Motivation: get better pump to idler energy conversion efficiency to the mid-infrared (MIR). • Upper bound of OPO: quantum efficiency. • Example: ws wp wi idler pump signal

  8. ws2 ws ws wp wi wi idler idler pump signal signal2 Simultaneous OPO and DFG* • A single quasi periodic crystal phase-matches two processes simultaneously wp ws ws ws wp wi ws2 OPO: ws=wp-wi Pump® Signal & Idler DFG: ws2=ws-wi Signal®Signal2 & Idler NIR MIR MIR *G. Porat, O. Gayer and A. Arie, Optics Letters 35, 1401 (2010)

  9. Quasi periodic structures Periodic real space structure: constructed from a single building blocks (in 1D) Quasi periodic real space structure: ordered, non-periodic, constructed from at least two building blocks (in 1D) Reciprocal space structure: dense, constructed from at least two incommensurate values 9

  10. The Dual Grid Method • Phase matches an arbitrary set of c(2) processes defined by a set of phase mismatches {Dk(i)} (b) Build the dual grid (a) Define mismatch vectors (c) Construct the tiling (d) Convert to a nonlinear photonic crystal 14.30mm 1 R. Lifshitz, A. Arie, A. Bahabad, Phys. Rev. Lett. 95, 133901 (2005). 2 A. Bahabad, N. Voloch, A. Arie, and R. Lifshitz, J. Opt. Soc. Am. B 24, 1916 (2007).

  11. Fourier coefficients OPO 0.4 DFG 0.4 Compare with 2/p~0.64 of periodic modulation Quasi periodic OPO-DFG* • T=125oC, lp=1.064mm, ls=1.45mm, li=3.95mm, ls2=2.3mm. *G. Porat, O. Gayer and A. Arie, Optics Letters 35, 1401 (2010)

  12. Independent Characterization of OPO and DFG Normalized efficiency vs. idler wavelength *G. Porat, O. Gayer and A. Arie, Optics Letters 35, 1401 (2010)

  13. Independent Characterization of OPO and DFG Normalized efficiency vs. idler wavelength Efficiency peaks in the T-lidler plane G. Porat, O. Gayer and A. Arie, Optics Letters 35, 1401 (2010)

  14. Independent Characterization of OPO and DFG1 The theoretical curves2 have been down-shifted by 37.7nm. Normalized efficiency vs. idler wavelength Efficiency peaks in the T-lidler plane 1 G. Porat, O. Gayer and A. Arie, Optics Letters 35, 1401 (2010) 2 O. Gayer, Z. Sacks, E. Galun, A. Arie, Appl. Phys. B 91, 343348 (2008).

  15. Quasi periodic OPO-DFG Performance Experimental results 18.3% 16.87% li=3915nm T=130oC hs=22.15% 13.60% hs=15.82% 175mW 300mW • Conversion efficiency for Ppump=1.5W improved by 24% • Slope efficiency improved by 40% • Reached 18.3% conversion efficiency at Ppump=2W

  16. Tunable and EfficientUp-Conversion G. Porat, H. Suchowski, Y. Silberberg and A. Arie, Optics Letters 35, 1590 (2010)

  17. The Challenge • Perform up-conversion in a single crystal with • a single fixed frequency source • wide temperature tuning bandwidth • high efficiency

  18. wSFW=wpump+wsignal wsignal c(2) crystal wpump The Challenge • Perform up-conversion in a single crystal with • a single fixed frequency source • wide temperature tuning bandwidth • high efficiency • SFG: wSFW=wpump+wsignal

  19. wSFW=wpump+wsignal wsignal c(2) crystal wpump The Challenge • Perform up-conversion in a single crystal with • a single fixed frequency source • wide temperature tuning bandwidth • high efficiency • Main limitation of the tuning bandwidth of SFG: dispersion • Greater for shorter wavelengths Small tuning bandwidth: 1.5nm around 629nm Image from W. R. Bosenberg, J. I. Alexander, L. E. Myers, and R. W. Wallace, Optics Letters 23, 207 (1998)

  20. Even if phase-matching is obtained, back-conversion still limits efficiency 1 0 z The Challenge • Perform up-conversion in a single crystal with • a single fixed frequency source • wide temperature tuning bandwidth • high efficiency

  21. Adiabatic Conversion Scheme • Counterintuitive. • An adiabatic process is characterized by very slow change rate. • To understand it better: He played with architecture, perspective and impossible spaces. His art continues to amaze and wonder millions of people all over the world. In his work we recognize his keen observation of the world around us and the expressions of his own fantasies. M.C. Escher shows us that reality is wondrous, comprehensible and fascinating.

  22. wSFW=wpump+wsignal c(2) crystal wsignal wpump Adiabatic SFG* • The crystal is chirped with a very low chirp rate • The phase-mismatch starts from a large negative value, and gradually increases. • Somewhere along the crystal the phase-mismatch goes through 0. • It continues to grow until it reaches a very large positive value *H. Suchowski, D. Oron, A. Arie and Y. Silberberg, Phys. Rev. A 78, 063821 (2008)

  23. wSFW=wpump+wsignal c(2) crystal wsignal wpump Adiabatic SFG* *H. Suchowski, D. Oron, A. Arie and Y. Silberberg, Phys. Rev. A 78, 063821 (2008)

  24. wSFW=wpump+wsignal wsignal wpump Adiabatic SFG* Dk(l1)=0 l1 *H. Suchowski, D. Oron, A. Arie and Y. Silberberg, Phys. Rev. A 78, 063821 (2008)

  25. wSFW=wpump+wsignal Wide wavelength acceptance bandwidth wsignal wpump Adiabatic SFG* Dk(l3)=0 Dk(l2)=0 Dk(l1)=0 l2 l1 l3 *H. Suchowski, D. Oron, A. Arie and Y. Silberberg, Phys. Rev. A 78, 063821 (2008)

  26. wSFW=wpump+wsignal Wide temperature acceptance bandwidth wsignal wpump Adiabatic SFG* Dk(T3)=0 Dk(T2)=0 Dk(T1)=0 T2 T1 T3 *H. Suchowski, D. Oron, A. Arie and Y. Silberberg, Phys. Rev. A 78, 063821 (2008)

  27. T [oC] Cascaded OPO and adiabatic SFG* Periodic Chirped wSFW=wp+ws Pump laser ws wp ASFG: wSFW=wp+ws Pump & Signal ® SFW OPO: ws=wp-wi Pump ® Signal & Idler *G. Porat, H. Suchowski, Y. Silberberg and A. Arie, Optics Letters 35, p. 1590 (2010)

  28. Cascaded OPO and adiabatic SFG* Periodic Chirped wSFW=wp+ws Pump laser ws wp ASFG: wSFW=wp+ws Pump & Signal ® SFW OPO: ws=wp-wi Pump ® Signal & Idler *G. Porat, H. Suchowski, Y. Silberberg and A. Arie, Optics Letters 35, p. 1590 (2010) T [oC]

  29. Cascaded OPO and adiabatic SFG* Periodic Chirped wSFW=wp+ws Pump laser ws wp ASFG: wSFW=wp+ws Pump & Signal ® SFW OPO: ws=wp-wi Pump ® Signal & Idler *G. Porat, H. Suchowski, Y. Silberberg and A. Arie, Optics Letters 35, p. 1590 (2010) T [oC]

  30. Cascaded OPO and adiabatic SFG* Periodic Chirped wSFW=wp+ws Pump laser ws wp ASFG: wSFW=wp+ws Pump & Signal ® SFW OPO: ws=wp-wi Pump ® Signal & Idler *G. Porat, H. Suchowski, Y. Silberberg and A. Arie, Optics Letters 35, p. 1590 (2010) T [oC]

  31. Unused! Unused! T [oC] Experimental results* • 6.2nm tuning bandwidth around 634nm • 2.7-3.9% pump to SFW conversion efficiency with 1W pump • Simulation: Sellmeier error is greater at shorter wavelength *G. Porat, H. Suchowski, Y. Silberberg and A. Arie, Optics Letters 35, p. 1590 (2010)

  32. Experimental results* • 4.7% pump to SFW conversion efficiency at 1.5W pump • Output mirror red transmittance is ~46% Þ~10% intracavity conversion efficiency *G. Porat, H. Suchowski, Y. Silberberg and A. Arie, Optics Letters 35, p. 1590 (2010)

  33. ADFG: ws2=ws-wi Signal ® Signal2 & Idler OPO: ws=wp-wi Pump ® Signal & Idler Summary – Down Coversion • First experimental demonstration of simultaneous parametric oscillation and signal to idler conversion using a single quasi-periodically modulated crystal. • Pump-to-idler conversion efficiency improved by 24% (from 13.6% to 16.87%). • Reached 18.3% conversion efficiency at Ppump=2W. • Slope efficiency improved by 40% (from 15.82% to 22.25%). • Further improvement: • OPO-QP-DFG • OPO-Adiabatic DFG idler idler pump signal signal2

  34. Summary – Up Conversion • Using a single crystal, we have experimentally demonstrated temperature tuned up-conversion of a fixed frequency laser. • Efficient up-conversion was obtained over a bandwidth of 6.2nm • Reached 4.7% conversion efficiency for average pump power of 1.5W. • Further improvement • Bandwidth: use OPO with greater signal tuning bandwidth • Efficiency: anti-reflection coating • Can also be used to efficiently generate tunable UV laser, e.g. with an OPO pumped by a frequency-doubled Nd:YAG laser

  35. Thank you Gil Porat Dept. of Physical Electronics Tel-Aviv University Tel: +972-3-6407545 Email: gilpor@gmail.com

  36. Simultaneity is also more efficient than cascading:longer and overlapping interaction lengths OPO: ws=wp-wi Pump® Signal & Idler DFG: ws2=ws-wi Signal®Signal2 & Idler Simultaneous OPO and DFG

  37. Optical Parametric Oscillation & SFG W. R. Bosenberg, J. I. Alexander, L. E. Myers, and R. W. Wallace, Optics Letters 23, 207 (1998) Small tuning bandwidth: 1.5nm around 629nm

  38. Independent Characterization of OPO and DFG1 Experimental results The theoretical curves2 have been down-shifted by 37.7nm. Efficiency peaks in the T-lidler plane 1 G. Porat, O. Gayer and A. Arie, Optics Letters 35, 1401 (2010) 2 O. Gayer, Z. Sacks, E. Galun, A. Arie, Appl. Phys. B 91, 343348 (2008).

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