Generation of narrowband THz radiation by surface-emitted optical rectification in periodically poled lithium niobate

We present theoretical and experimental results of THz-wave generation via optical rectification in periodically poled lithium niobate (PPLN) crystal. The rectified field in both frequency and time domain is calculated taking into account the divergence of the exciting optical beam. The dependence of the central frequency of the narrow-band THz-wave on of direction of field emission is investigated. The surface- emitting geometry (when the THz-wave is observed in direction perpendicular to the direction of the optical pulse propagation) reduces the damping of the THz-wave in the PPLN crystal considerably. In this geometry the measured central frequency is around 1 THz for our PPLN crystal with a poling period of (Lambda) equals 127 micrometers . The frequency is tuned by rotation of the crystal over a range of 0.65 - 1.1 THz. Typical bandwidths of 50 - 100 GHz were observed, depending on the collection angle and the number of periods involved.

[1]  William M. Robertson.  Optoelectronic Techniques for Microwave and Millimeter-Wave Engineering , 1995 .

[2]  Almantas Galvanauskas,et al.  Generation of narrow-band terahertz radiation via optical rectification of femtosecond pulses in periodically poled lithium niobate , 2000 .

[3]  Hiromasa Ito,et al.  Tunable terahertz-wave generation in DAST crystal with dual-wavelength KTP optical parametric oscillator , 2000 .

[4]  K. Kawase,et al.  Enhancement of terahertz-wave output from LiNbO(3) optical parametric oscillators by cryogenic cooling. , 1999, Optics letters.

[5]  Jacob B. Khurgin.  Comparison of different optical methods of THz generation , 1999, Photonics West.

[6]  E. Brown,et al.  Coherent millimeter‐wave generation by heterodyne conversion in low‐temperature‐grown GaAs photoconductors , 1993 .

[7]  B. J. Clifton,et al.  cw generation of tunable narrow‐band far‐infrared radiation , 1974 .

[8]  R. Beigang,et al.  Generation of tunable narrow-band surface-emitted terahertz radiation in periodically poled lithium niobate. , 2001, Optics letters.

[9]  Simon Ramo,et al.  Fields and waves in modern radio , 1944 .

[10]  P. K. Tien,et al.  OPTICAL SECOND HARMONIC GENERATION IN FORM OF COHERENT CERENKOV RADIATION FROM A THIN‐FILM WAVEGUIDE , 1970 .

[11]  Xiang Zhang,et al.  Terahertz beam generation by femtosecond optical pulses in electro‐optic materials , 1992 .

[12]  T. Norris,et al.  Temperature dependence of narrow-band terahertz generation from periodically poled lithium niobate , 2000 .

[13]  Kodo Kawase,et al.  Tunable terahertz-wave parametric oscillators using LiNbO/sub 3/ and MgO:LiNbO/sub 3/ crystals , 2000 .

[14]  Paul R. Berman,et al.  Generation of Far Infrared as a Difference Frequency , 1965 .

[15]  Hanspeter Helm,et al.  Far Infrared Properties of Electro-Optic Crystals Measured by THz Time-Domain Spectroscopy , 1999 .

[16]  Andrew G. Glen,et al.  APPL , 2001 .