Y. P. Zhou

Comparison of simultaneous multiple wavelength lasing in various neodymium host crystals at transitions from 4F3/2–4I11/2 and 4F3/2–4I13/2

The possibility of simultaneous multiple wavelength lasing in various neodymium host crystals such as Nd:YAG, Nd:YLF, Nd:BEL, and Nd:YAP has been analyzed by the ‘‘oscillation condition.’’ It is shown that this kind of laser can be realized in all the described crystals in pulsed state, but only achieved in the Nd:YAP crystal in continuous‐wave state. On the basis of the analyzed results, we have achieved cw simultaneous multiple wavelength lasing in Nd:YAP crystal for the first time at both 1.0795 and 1.3414 μm.

Simultaneous multiple wavelength laser action in various neodymium host crystals

The oscillation condition of a simultaneous multiple wavelength laser has been established and used to analyze the possibility of simultaneous oscillation in various neodymium host crystals, such as Nd:YAG, Nd:YLF, Nd:BEL, and Nd:YAP crystals at the transitions from /sup 4/F/sub 3/2/-/sup 4/I/sub 13/2/ and /sup 4/F/sub 3/2/-/sup 4/I/sub 11/2/. It is shown that this kind of laser can be realized in all the described crystals in a pulsed state. In general, continuous wave (CW) operation, however, can only be achieved for Nd:YAP. On the basis of these results, CW simultaneous double wavelength lasing has been achieved in a Nd:YAP crystal for the first time at both 1.0795 mu m and 1.314 mu m. >

1079.5- and 1341.4-nm: larger energy from a dual-wavelength Nd:YAlO 3 pulsed laser

On the basis of oscillation conditions of simultaneous multiple-wavelength lasing that we have established, a larger-energy (1079.5 and 1341.4 nm) dual-wavelength Nd:YAlO(3) pulsed laser has been developed. Output energies of 3.71 and 1.39 J with efficiencies of 1.29% and 0.48% for the 1341.4-and 1079.5-nm wavelengths, respectively, have been achieved. To our knowledge, this is the best result among simultaneous dual-wavelength solid-state lasers to date. The temporal and spatial distributions of these beams obtained from a free-running dual-wavelength Nd:YAlO3 pulsed laser have also been measured. Experimental results show that the temporal and spatial overlap of the two beams is quite good for this type of laser.

Second harmonic generation and sum frequency mixing of dual wavelength Nd:YAlO/sub 3/ laser in flux grown KTiOPO/sub 4/ crystal

On the basis of accurately measured refractive indexes, the authors have obtained the Sellmeiers equations for flux grown KTiOPO/sub 4/ (KTP) crystal and used them to calculate the phase matched angles ( theta /sub m/, phi /sub m/) and effective nonlinear coefficients (d/sub eff/) for type I and III second harmonic generation (SHG) and sum frequency mixing (SFM) of radiations at 1.0795 and 1.3414 mu m. The optimum phase matching conditions for 1.0795 and 1.3414 mu m SHG are that theta /sub m/=86.88 and 58.88 degrees , respectively, in an XZ plane ( phi =0) and for SMF of 1.0795 and 1.3414 mu m in the same plane 76.02 degrees . The corresponding d/sub eff/ values calculated from theta /sub m/s are 18.07*10/sup -9/ and 17.42*10/sup -9/ esu. >

Measurement of the refractive index and thermal refractive index coefficients of Nd:YAP crystal

The principal refractive indices of yttrium aluminate crystal doping with 1-wt.% neodymium (Nd:YAP) have been measured by a minimum deviation method for the wavelengths 0.5398, 0.6328, and 1.0795 microm in the temperature range of 289-435 K. The thermal refractive index coefficients have been obtained at these wavelengths, and they are all positive and slightly decrease with increased wavelength. The constants of the single term Sellmeier equation are also given for the 273-420 K temperature range. These constants are in linear relationship with temperature in the 4 x 10(-3) error range.

Measurement of the stimulated emission cross section for the /sup 4/F/sub 3/2/-/sup 4/I/sub 13/2/ transition of Nd/sup 3+/ in YAlO/sub 3/ crystal

A method for the simultaneous measurement of the stimulated emission cross section and fluorescence lifetime by studying the relation between laser parameters and the laser relaxation oscillation frequency is discussed. The stimulated emission cross section for the /sup 4/F/sub 3/2/-/sup 4/I/sub 13/2/ transition of Nd/sup 3+/ ion in YAP crystal was measured to be (22+or-1)*10/sup -20/ cm/sup 2/. >

Laser action of Nd:YAlO3 at 1300 nm

From our measured value of the stimulated emission cross section for 4F3/2–4I13/2 transition of Nd3+ ion in YAlO3 crystal as well as the results of continuous wave (cw) and pulsed 1341.4 nm Nd:YAP lasers, it can be seen that Nd:YAP is an excellent 1300 nm laser crystal. In our laboratory cw output power of 195.8 W at 1341.4 nm with an overall efficiency of 1.43% and pulsed output energy of 5.1 J at 1341.4 nm with an overall efficiency of 2.02% have been achieved by using this kind of crystal.

Second‐harmonic generation and sum‐frequency mixing of double‐wavelength Nd:YALO3 laser to 413.7‐nm violet coherent radiation in LiIO3 crystal

A new method to get 413.7‐nm violet coherent radiation by using second‐harmonic generation and sum‐frequency mixing of radiation from a 1341.4‐ and 1079.5‐nm dual‐wavelength Nd:YALO3 laser in a LiIO3 crystal is reported in this communication. First, the 670.7‐nm red coherent radiation is obtained by second‐harmonic generation of 1341.4‐nm radiations in a LiIO3 crystal, and then the 670.7‐ and 1079.5‐nm radiations are mixed again in a second LiIO3 crystal to get 413.7‐nm radiation. The phase‐matching angles are obtained for both nonlinear optical processes. The experimental results agree well with calculated results.

Twice sum‐frequency mixing of a dual‐wavelength Nd:YALO3 laser to get 413.7‐nm violet coherent radiation in LiIO3 crystal

A new method to obtain 413.7‐nm violet coherent radiation by second‐order sum‐frequency mixing of the outputs (1341.4 and 1079.5 nm) of a double‐wavelength Nd:YALO3 (Nd:YAP) laser in two LiIO3 crystals is reported. First, a 598.1‐nm orange coherent radiation is obtained by sum‐frequency mixing (SFM) of 1341.4‐ and 1079.5‐nm radiations in a LiIO3 crystal, and then the 598.1‐ and 1341.4‐nm radiations are mixed again in a second LiIO3 crystal to get 413.7‐nm radiation. The phase‐matching angles are obtained for both SFM processes. The experimental results agree well with calculated results.

Measurement of the total absorption coefficient of a KTP crystal

Abstract The laser calorimetric measurement of the absorption coefficient in a small cubic 12 × 9 × 9 mm KTP crystal has been investigated experimentally. The absorption coefficient in this crystal is 0.0121 cm -1 , and the measurement accuracy is within 10%.