Quasi-phase-matched generation of coherent extreme-ultraviolet light

High-harmonic generation is a well-known method of producing coherent extreme-ultraviolet (EUV) light, with photon energies up to about 0.5 keV (refs 1, 2). This is achieved by focusing a femtosecond laser into a gas, and high harmonics of the fundamental laser frequency are radiated in the forward direction. However, although this process can generate high-energy photons, efficient high-harmonic generation has been demonstrated only for photon energies of the order 50–100 eV (ref. 5). Ionization of the gas prevents the laser and the EUV light from propagating at the same speed, which severely limits the conversion efficiency. Here we report a technique to overcome this problem, and demonstrate quasi-phase-matched frequency conversion of laser light into EUV. Using a modulated hollow-core waveguide to periodically vary the intensity of the laser light driving the conversion, we efficiently generate EUV light even in the presence of substantial ionization. The use of a modulated fibre shifts the energy spectrum of the high-harmonic light to significantly higher photon energies than would otherwise be possible. We expect that this technique could form the basis of coherent EUV sources for advanced lithography and high-resolution imaging applications. In future work, it might also be possible to generate isolated attosecond pulses.

[1]  Henry C. Kapteyn,et al.  GENERATION OF COHERENT SOFT X RAYS AT 2.7 NM USING HIGH HARMONICS , 1997 .

[2]  N. Bloembergen,et al.  Interactions between light waves in a nonlinear dielectric , 1962 .

[3]  Kaplan,et al.  Optimal quasi-phase-matching for high-order harmonic generation in gases and plasma. , 1994, Physical review. A, Atomic, molecular, and optical physics.

[4]  R L Byer,et al.  42%-efficient single-pass cw second-harmonic generation in periodically poled lithium niobate. , 1997, Optics letters.

[5]  C. Peters,et al.  Generation of optical harmonics , 1961 .

[6]  Catherine M. Herne,et al.  Phase matching of high-order harmonics in hollow waveguides , 1999, 2404.00071.

[7]  Nai-Ben Ming,et al.  Quasi-phase-matched third-harmonic generation in a quasi-periodic optical superlattice , 1997 .

[8]  M. Murnane,et al.  Phase-matched generation of coherent soft X-rays , 1998, Science.

[9]  Yijin Liu,et al.  Fully spatially coherent EUV light generated using a small-scale laser , 2002 .

[10]  M. Fejer,et al.  Quasi-phase-matched second harmonic generation: tuning and tolerances , 1992 .

[11]  U. Heinzmann,et al.  Attosecond metrology , 2007, Nature.

[12]  H. R. Lange,et al.  High-Order Harmonic Generation and Quasiphase Matching in Xenon Using Self-Guided Femtosecond Pulses , 1998 .

[13]  A. Yariv,et al.  Phase matching by periodic modulation of the nonlinear optical properties , 1972 .

[14]  L. A. Lompré,et al.  Multiple-harmonic conversion of 1064 nm radiation in rare gases , 1988 .

[15]  Randy A. Bartels,et al.  Generation of Spatially Coherent Light at Extreme Ultraviolet Wavelengths , 2002, Science.

[16]  Charles K. Rhodes,et al.  Studies of multiphoton production of vacuum-ultraviolet radiation in the rare gases , 1987 .

[17]  S L Voronov,et al.  Control of laser high-harmonic generation with counterpropagating light. , 2001, Physical review letters.

[18]  Ferenc Krausz,et al.  Generation of Coherent X-rays in the Water Window Using 5-Femtosecond Laser Pulses , 1997 .

[19]  M Murnane,et al.  Quasi-phase matching of high-harmonics and attosecond pulses in modulated waveguides. , 2000, Optics express.

[20]  N. Bloembergen.  Nonlinear Optics (4th Edition) , 1996 .

[21]  I. Christov,et al.  Shaped-pulse optimization of coherent emission of high-harmonic soft X-rays , 2000, Nature.

[22]  Henry C. Kapteyn,et al.  High-Harmonic Generation of Attosecond Pulses in the ``Single-Cycle'' Regime , 1997 .

[23]  M M Murnane,et al.  Generation of broadband VUV light using third-order cascaded processes. , 2001, Physical review letters.

[24]  M M Murnane,et al.  High-efficiency, single-stage 7-kHz high-average-power ultrafast laser system. , 2001, Optics letters.