Intracavity Sum-frequency Mixing Research Articles

486 nm pulsed Nd:YLF laser with intracavity sum-frequency mixing

An intracavity sum-frequency pulsed laser emitting at 486 nm was demonstrated in a combined cavity for two electro-optically Q-switched Nd:YLF fundamental lasers emitting at 908 nm and 1047 nm respectively. Pumped by two 806 nm LDs at 50 Hz repetition rate, while the intracavity pulse energy reached 6.25 mJ at 908 nm and 2.57 mJ at 1047 nm, maximum output pulse energy of 0.26 mJ at 486.4 nm wavelength was successfully achieved by intracavity sum-frequency. The corresponding spectral bandwidth was less than 0.08 nm, and the pulse width was about 11.8 ns. The peak power of the blue laser pulse was up to 21.8 kW, and the results provided a new blue pulsed laser source around 486 nm for ocean detection applications.

Intra-cavity dark pulse generation through synchronized sum-frequency mixing

A Nd:YVO4 laser operating at 1064 nm generating a stable mode-locked train of 10 ps-long dark pulses with a 211 MHz repetition rate is presented. The mode-locking relies on a periodic loss modulation produced by intra-cavity sum-frequency mixing with a synchronous bright-pulse train from a mode-locked femtosecond Yb:KYW laser at 1040 nm. A modulation depth of 90% was achieved for the dark pulses, confirmed by cross-correlation measurements. The ultrafast loss modulation injects power into the Nd:YVO4 laser cavity modes beyond the laser gain bandwidth. At proper laser cavity length, the detuning interaction of these modes with the lasing modes leads to the generation of periodic ultrafast transients at frequencies above 1.5 THz.

Development and application of an airborne differential absorption lidar for the simultaneous measurement of ozone and water vapor profiles in the tropopause region.

A new, combined, lidar system has been developed that is able to simultaneously measure profiles of ozone and water vapor onboard aircraft. The concurrent measurement of these complementary trace species in the upper troposphere and lower stratosphere allows inferring exchange processes in the tropopause region. Whereas an advanced H2O differential absorption lidar at 935 nm has successfully been developed and extensively tested at DLR in the past, we describe here an amendment of this lidar by the addition of an ultraviolet (UV) channel to measure ozone. The transmitter of the ozone differential absorption lidar (DIAL) is based on a near-IR optical parametric oscillator that is frequency-converted into the UV spectral range by intracavity sum frequency mixing. Hereby, a continuous UV tuning range of ∼297-317 nm has been achieved. The average output power in this range is higher than 1 W corresponding to more than 10 mJ per pulse at a repetition rate of 100 Hz. The ozone DIAL system has been carefully characterized both on the ground and in flight. The first simultaneously measured two-dimensional cross-sections of ozone and water vapor in the upper troposphere and lower stratosphere have been recorded during the Wave-driven Isentropic Exchange (WISE) field campaign in 2017 demonstrating the high potential of this system for studying exchange processes in this region of the atmosphere.

430nm DPSS blue laser generated by sum-frequency mixing

An all-solid-state blue laser at 430nm generated by intracavity sum-frequency mixing of a Nd: YAG laser emitting at 1319nm and a Pr:YLF laser at 639.5nm is presented. The continuous output power of 430nm is over 190mW which is the highest laser power emitting at this wavelength according to current report. The Nd: YAG and Pr:YLF crystal was pumped by a 5.9W 808nm and a 3.0W 444nm laser diode respectively. The optical-to-optical conversion efficiency is 2.1%.

Continuous-wave yellow laser generation at 578 nm by intracavity sum-frequency mixing of thin disk Yb:YAG laser and Nd:YAG laser

We report a continuous-wave yellow laser at 578nm obtained by doubly resonant intracavity sum-frequency mixing of thin disk Yb:YAG laser and Nd:YAG laser with a LBO nonlinear crystal. Single-wavelength laser operation at 578nm by using a silica etalon as a wavelength selector and dual-wavelength operation at 578nm and 582nm are obtained with maximum output powers of 100mW and 136mW, respectively. The single wavelength operating power stability value in 30min was ~4.7%, which was improved ∼21.6%, compared with that of dual-wavelength operation.

High power tunable femtosecond ultraviolet laser source based on an Yb-fiber-laser pumped optical parametric oscillator.

We report a high average power tunable 51 MHz femtosecond ultraviolet (UV) laser source based on an intra-cavity sum frequency mixing optical parametric oscillator (OPO) pumped by a fiber laser. The UV laser is generated by sum frequency generation (SFG) between the second harmonic of a mode-locked Yb-fiber laser and the signal of the OPO. A non-collinear configuration is used in the SFG to compensate the group velocity mismatch, and to increase the SFG conversion efficiency dramatically. Tunable ultraviolet pulses within the wavelength range from 385 to 400 nm have been produced with a maximum average power of 402 mW and a pulse width of 286 fs at 2 W Yb-fiber laser pump, corresponding to 20.1% near-infrared to UV conversion efficiency at 387 nm. To our knowledge, this is the first demonstration of tunable femtosecond UV pulse generation from a fiber laser pumped OPO, and is also the highest average power tunable UV femtosecond pulses from an OPO.

LD 泵浦全固态 608.1 nm 和频激光器

A compact all-solid-state intracavity sum-frequency mixing laser at 608. 1 nm is reported. A Nd∶YAG crystal and a Nd∶ YVO4 crystal are pumped by two laser diodes respectively in two sub-arms of the laser cavity. In the two arms,laser wavelengths of 1 342 nm from Nd∶ YVO4crystal( corresponding to the4F3 /2-4I13 /2transition) and 1 112 nm from Nd∶ YAG crystal( corresponding to the4F3 /2-4I11 /2transition) are selected to be mixed into 608. 1 nm laser. Through optimization of the cavity design,better matching of the modes for the two wavelengths is obtained. In the overlapping of the two arms,sum-frequency mixing is generated with a type I phase-matching LBO crystal. The experiment result shows that a stable and low noisy output of 23. 8 m W at608. 1 nm is obtained at the incident pump power of 740 m W for the Nd∶ YAG crystal and 600 m W for the Nd∶ YVO4 crystal. It is an efficient way to obtain 608. 1 nm laser with the sum-frequency mixing structure proposed in this article.

Efficient yellow beam generation by intracavity sum frequency mixing in DPSS Nd:YVO4 laser

We present our studies on dual wavelength operation using a single Nd:YVO4 crystal and its intracavity sum frequency generation by considering the influence of the thermal lensing effect on the performance of the laser. A KTP crystal cut for type-II phase matching was used for intracavity sum frequency generation in the cavity at an appropriate location for efficient and stable yellow output power. More than 550 mW of stable CW yellow-orange beam at 593.5 nm with beam quality parameter (M2) ∼4. 3 was obtained. The total pump to yellow beam conversion efficiency was estimated to be 3.83%.

An efficient cw laser at 560 nm by intracavity sum-frequency mixing in a self-Raman Nd:LuVO4 laser

We report for the first time efficient continuous wave (cw) laser emission at 560 nm by sum-frequency mixing of the fundamental and first-Stokes fields generated within a Nd:LuVO4 self-Raman laser. Intracavity sum-frequency mixing with LiB3O5 nonlinear crystal yielded 4.2 W of visible yellow emission, corresponding to an optical conversion efficiency of 22.9% with respect to the incident pump power; the output power stability over 4 h was better than 3.5%. We discuss the balance that must be maintained between the two nonlinear processes of Raman generation and sum-frequency mixing in order to obtain maximum emission at 560 nm.

Continuous-wave dual-wavelength Nd:YAG laser operation at 1319 and 1338 nm

We report an efficient continuous-wave (CW) dual-wavelength operation of an Nd:YAG (YAG: yttrium aluminum garnet) laser at 1319 and 1338 nm. An output power of 2.47 W for the dual-wavelength operation was achieved at the incident pump power of 16.7 W. Intracavity sum-frequency mixing at 1319 and 1338 nm was then realized in an LBO (lithium triborate) crystal to reach the red range. A maximum output power of 879 mW in the red spectral range at 664 nm has been achieved. The red output stability is better than 3.4%. The red beam quality M2 values are about 1.21 and 1.35 in the horizontal and vertical directions respectively.

Nanosecond nonlinear Čerenkov conical beams generation by intracavity sum frequency mixing in KTiOAsO_4 crystal

Nanosecond Čerenkov-type conical beam at 628 nm is obtained by intracavity sum frequency mixing (SFM) of 1064 and 1534 nm in KTiOAsO(4) (KTA) crystal. The 1534 nm signal generated by the KTA optical parametric oscillation (OPO), respectively, interacts with the orthogonally polarized 1064 nm radiations by the nonlinear Čerenkov SFM, emitting two red rings with cone angles of 11.4° and 16.0°, respectively. Multidomain structure observed in the KTA crystal can account for the corresponding phenomenon. The KTA crystal simultaneously serves as OPO medium and Čerenkov radiation emitter in this experiment, indicating that it is a promising multifunctional nonlinear crystal material. Furthermore, the naturally grown crystal combined with intracavity Čerenkov-type configuration will provide a simple and compact approach, opening a door for the wide application of nonlinear Čerenkov radiation sources due to its cost-effectiveness.

All-solid-state doubly resonant intracavity frequency sum mixing orange yellow laser with 3.2 W output power at 593.5 nm

A compact and efficient 593.5 nm orange-yellow laser is realized using doubly resonant intracavity sum frequency mixing. Two Nd: YVO4 crystals are employed as the gain crystals. In two sub-cavities, 1064 nm radiation from one Nd: YVO4 and 1342 nm radiation from the other Nd: YVO4 are mixed to generate 593.5 nm orange-yellow laser. In the overlapping of the two cavities, sum frequency mixing is achieved in a type I critical phase matching (CPM) LBO crystal. An output power of 3.2 W at the wavelength of 593.5 nm is obtained with total incident pump power of 38 W. The optical to optical conversion efficiency is up to 8.4% and the stability of the output power is better than 2.48% in 8 h. To the best knowledge, this it the highest watt-level laser at 593.5 nm generated by diode end pump all-solid-state technology.

Efficient dual-wavelength Nd:YVO4 laser at 1085 and 1342 nm and sum-frequency mixing for an orange emission

We report on the efficient continuous-wave (CW) dual-wavelength operation of a Nd:YVO4 laser at 1085 and 1342 nm. An output power of 1.72 W for the dual-wavelength was achieved at the incident pump power of 17.4 W. Intracavity sum-frequency mixing at 1085 and 1342 nm was then realized in a KTP crystal to reach the orange range. A maximum output power of 146 mW in the orange spectral range at 600 nm has been achieved. The orange output stability is better than 3.8%. The orange beam quality M 2 value is about 1.41 and 1.25 in both horizontal and vertical dimensions, respectively.

Calculation of the stationary generation power of a solid-state raman laser with intracavity second harmonic generation and sum frequency mixing

Analytical equations for the power of second-harmonic stationary generation or sum frequency mixing in a Raman laser with an intracavity nonlinear medium are developed and analyzed as functions of pumping mode and other parameters of the laser system. Parameter relationships providing the maximum output power and conditions for suppression of both stimulated Raman scattering by sum frequency mixing and; consequently, of sum frequency mixing itself are found.

All-solid-state continuous wave doubly linear resonator sum-frequency mixing yellow laser

We report a continuous-wave (CW) yellow laser emission by sum-frequency mixing in Nd:YVO4 crystal. Using type-II critical phase-matching KTP crystal, a yellow laser at 593.5 nm is obtained by 1064 and 1342 nm intracavity sum-frequency mixing. The maximum laser output power of 2.1 W is obtained when an incident pump laser of 18.2 W is used. At the output power level of 2.1 W, the output stability is better than 3.2%.

High power single-longitudinal-mode cyan laser at 500.8 nm

An all-solid-state single-longitudinal-mode (SLM) laser at 500.8 nm with 830 mW output power has been demonstrated for the first time. By using a new resonator for doubly resonant, Nd:GdVO4 and Nd:YAG were pumped by two laser diode arrays coupled by optical fiber, respectively. In the two sub-cavities, SLM wavelengths of 1064 and 946 nm were induced by using the twisted-mode technique and then mixed into SLM 500.8 nm laser with sum-frequency technology. The SLM 500.8 nm laser output of 830 mW was obtained at the incident pump power of 20 W for Nd:GdVO4 and 23 W for Nd:YAG. The experimental results showed that the intracavity sum-frequency mixing by twisted-mode technique is an effective method for SLM 500.8 nm laser.

Diode-pumped green light source based on intracavity sum frequency generation

We report a continuous-wave (CW) green laser emission by sum-frequency mixing in Nd:YVO4 and Nd:YLF crystals. Using type-II critical phase-matching (CPM) KTP crystal, a green laser at 539 nm is obtained by 914 and 1313 nm intracavity sum-frequency mixing. The maximum laser output power of 388 mW is obtained when an incident pump laser of 18.2 W is used. At the output power level of 388 mW, the output stability is better than 4.6%.

494 nm blue laser based on sum-frequency mixing of diode pumped Nd3+ lasers

We report for the first time a continuous-wave (CW) blue radiation at 494 nm by intracavity sumfrequency generation of 912 nm Nd:GdVO4 laser and 1079 nm Nd:YAlO3 (Nd:YAP) laser. Using type-I critical phase matching LiB3O5 (LBO) crystal, 494 nm blue laser was obtained by 912 and 1079 nm intra-cavity sum-frequency mixing, and output power of 179 mW was demonstrated. At the output power level of 179 mW, the output power stability is better than 3.5% and laser beam quality M 2 factor is 1.21.

CW green laser at 520 nm based on sum-frequency mixing of diode pumped Yb:YAG laser

We report for the first time a continuous-wave (CW) green laser emission by sum-frequency mixing in Yb:YAG crystal. Using type-I critical phase-matching LBO crystal, a green laser at 520 nm is obtained by 1030 and 1048 nm intracavity sum-frequency mixing. The maximum laser output power of 269 mW is obtained when an incident pump laser of 17.8 W is used. At the output power level of 269 mW, the output stability is better than 3.2%.

504 nm blue-green laser based on sum-frequency mixing of diode pumped Nd3+ lasers

We report for the first time a continuous-wave (CW) blue-green radiation at 504 nm by intracavity sum-frequency generation of 946 nm Nd:YAG laser and 1080 nm Nd:YAlO3 (Nd:YAP) laser. Using type-I critical phase matching LiB3O5 (LBO) crystal, 504 nm blue-green laser was obtained by 946 and 1080 nm intra-cavity sum-frequency mixing, and output power of 215 mW was demonstrated. At the output power level of 215 mW, the output power stability is better than 4.7% and laser beam quality M2 factor is 1.21.