“…4a . Moreover, the maximum output power as high as 1.37 W was recent realized at 213 nm with the efficiency over than 17% with a BBO crystal by the well-designed sum-frequency technique 18 , which indicates that the BBO crystal could be an excellent ultraviolet crystal and suitable for the high-power ultraviolet lasers with the APP strategy.…”
Section: Resultsmentioning
confidence: 99%
“…In 1962, Armstrong et al proposed that if the interacting waves could be totally reflected after a propagation distance of , then the phase shift of π at the interfaces could compensate for the phase mismatch of π, as shown in Fig. 1a , which also derives the QPM conditions 18 . Fig.…”
Section: Resultsmentioning
confidence: 99%
“…To realize highly efficient optical conversion, a phase-matching condition between the fundamental and harmonic electromagnetic waves is required. This prerequisite was realized in many anisotropic crystals with inherent birefringence, which broadens the available wavelength of laser sources 17 , 18 but concurrently precludes many nonlinear materials without suitable birefringence. To break the strict birefringent limitation, the quasi-phase-matching (QPM) technique was proposed in 1962 by employing periodic inversion of the polarization direction of nonlinear crystals 19 , which has been demonstrated in many ferroelectric materials 20 – 22 and applied in classical and quantum optics fields for the generation of frequency conversion, nonlinear imaging, quantum information generation and computation 23 – 25 .…”
Manipulation of the light phase lies at the heart of the investigation of light-matter interactions, especially for efficient nonlinear optical processes. Here, we originally propose the angular engineering strategy of the additional periodic phase (APP) for realization of tunable phase matching and experimentally demonstrate the widely tunable phase-matched second harmonic generation (SHG) which is expected for dozens of years. With an APP quartz crystal, the phase difference between the fundamental and frequency-doubled light is continuously angularly compensated under this strategy, which results the unprecedented and efficient frequency doubling at wavelengths almost covering the deep-UV spectral range from 221 to 332 nm. What’s more, all the possible phase-matching types are originally realized simultaneously under the angular engineering phase-matching conditions. This work should not only provide a novel and practical nonlinear photonic device for tunable deep-UV radiation but also be helpful for further study of the light-matter interaction process.
“…4a . Moreover, the maximum output power as high as 1.37 W was recent realized at 213 nm with the efficiency over than 17% with a BBO crystal by the well-designed sum-frequency technique 18 , which indicates that the BBO crystal could be an excellent ultraviolet crystal and suitable for the high-power ultraviolet lasers with the APP strategy.…”
Section: Resultsmentioning
confidence: 99%
“…In 1962, Armstrong et al proposed that if the interacting waves could be totally reflected after a propagation distance of , then the phase shift of π at the interfaces could compensate for the phase mismatch of π, as shown in Fig. 1a , which also derives the QPM conditions 18 . Fig.…”
Section: Resultsmentioning
confidence: 99%
“…To realize highly efficient optical conversion, a phase-matching condition between the fundamental and harmonic electromagnetic waves is required. This prerequisite was realized in many anisotropic crystals with inherent birefringence, which broadens the available wavelength of laser sources 17 , 18 but concurrently precludes many nonlinear materials without suitable birefringence. To break the strict birefringent limitation, the quasi-phase-matching (QPM) technique was proposed in 1962 by employing periodic inversion of the polarization direction of nonlinear crystals 19 , which has been demonstrated in many ferroelectric materials 20 – 22 and applied in classical and quantum optics fields for the generation of frequency conversion, nonlinear imaging, quantum information generation and computation 23 – 25 .…”
Manipulation of the light phase lies at the heart of the investigation of light-matter interactions, especially for efficient nonlinear optical processes. Here, we originally propose the angular engineering strategy of the additional periodic phase (APP) for realization of tunable phase matching and experimentally demonstrate the widely tunable phase-matched second harmonic generation (SHG) which is expected for dozens of years. With an APP quartz crystal, the phase difference between the fundamental and frequency-doubled light is continuously angularly compensated under this strategy, which results the unprecedented and efficient frequency doubling at wavelengths almost covering the deep-UV spectral range from 221 to 332 nm. What’s more, all the possible phase-matching types are originally realized simultaneously under the angular engineering phase-matching conditions. This work should not only provide a novel and practical nonlinear photonic device for tunable deep-UV radiation but also be helpful for further study of the light-matter interaction process.
“…We believe that the results demonstrated in this work are of great significance for the future realization of practical and industrially-applied, high power, high repetition rate, high beam quality and stable picosecond pulsed laser sources. Furthermore, the moderate single pulse energy (~μJ) of this system also makes it an ideal source for applications in nonlinear optics, such as second-order nonlinear frequency conversion [25,26], and high-power crystalline-based wavelength convertors using the stimulated Raman/Brillouin scattering process [27][28][29][30][31].…”
We demonstrate a high-power Nd: YVO4 picosecond laser amplifier that is capable of generating 51.5 W of average output power at a wavelength of 1,064 nm, with a repetition rate of 70 MHz and a pulse duration of 8.5 ps. This system encompasses three stages of laser diode end-pumped Nd: YVO4 amplification including two double-pass amplifiers and a single-pass amplifier. Laser output with near-diffraction-limited beam quality (M2 < 1.1) was maintained throughout the entire power scaling range of the laser. The system exhibited very high output power stability with a root-mean-square amplitude fluctuation of less than 0.2% over a period of 15 h of continuous operation.
“…7 Previous reports have demonstrated that this large π-conjugated group plays a crucial role for the large SHG response in famous β-BaB 2 O 4 (BBO) crystal 8,9 and also strong anisotropic birefringence in α-BaB 2 O 4 (α-BBO) 10 and Ba 2 M(B 3 O 6 ) 2 (M = Mg and Ca). 11,12 BBO crystals have been applied widely in the second harmonic generation (SHG) of the Nd-based laser, 13,14 as well as in the quantum-entangled photon pairs and microscale optical modulation. 15,16 The first-principles calculations were adopted to show that the contributions that the π-conjugated (B 3 O 6 ) 3− groups make to its SHG coefficient d 11 is more than 80%.…”
Electron−phonon (e−ph) coupling, representing an interaction term connecting the electronic states and lattice vibrations, is an important hot topic in physical and chemistry frontiers. However, the e−ph coupling intensity dependence on the structural motifs is not well understood at present. Borate crystal containing conjugated πbonds is an important functional material for optical applications. Here, we investigated the relationship between the e−ph coupling intensity and the π-conjugated borate groups, including small π-conjugated (BO 3 ) 3− and large π-conjugated (B 3 O 6 ) 3− motifs. Compared with α-Ba 3 Gd(BO 3 ) 3 , the e-ph coupling intensity of Ba 3 Gd(B 3 O 6 ) 3 was greatly enhanced. The fitted Huang−Rhys factor of Ba 3 Gd(B 3 O 6 ) 3 was 3 times larger than that of α-Ba 3 Gd(BO 3 ) 3 , thus manifesting the strengthened phonon-assisted photon luminescence. Such substantial improvement could be attributed to the shortened B−O bond length and increased electron density on the conjugated (B 3 O 3 ) six-member ring. Our work not only provides a helpful guideline to search strong coupling in rare-earth materials but also paves new routes for π-conjugated functional materials with the e−ph coupling effect, for example, organic laser crystals and light-induced phase transitions.
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