Optical field dynamics in a wavelength-versatile, all-solid-state intracavity cascaded pulsed Raman laser

Monitoring the optical field energies in an intracavity cascaded crystalline pulsed Raman laser enables us to probe the dynamics and optimise the performance of the laser, which produces up to 2.1 W average output power at 4 wavelengths between 532 and 636 nm selectable by simple angle tuning.     

High average power,all-solid-state external resonator Raman laser

As much as 3 W of average power at 1064 nm from a diode-pumped Nd:YAG laser, Q switched at 4 kHz, was used to pump an external-resonator, crystalline Ba(NO3)2 Raman laser generating a maximum of 1.3-W output at the first Stokes wavelength of 1197 nm. The slope efficiency was 63% with respect to the fundamental power incident on the Ba(NO3)2 crystal. A reduction in the beam quality of the Stokes output from M2 approximately 1.4 at lower Stokes powers to M2 approximately 3.4 at higher powers is attributed to thermal loading of the Raman-active crystal.     

Theory of an intracavity Raman laser

The quantum mechanical Langevin equations of a cavity where laser action takes place both by ordinary population inversion and stimulated Raman scattering is discussed for both single mode and multimode oscillation of the pump and Raman laser. Expressions for amplitude correlation and linewidth due to phase diffusion are obtained both for homogeneous and inhomogeneous broadening.     

Continuous-wave, singly resonant, intracavity parametric oscillator

Performance characteristics of a continuous-wave intracavity optical parametric oscillator are described by use of an experimental arrangement comprising a KTP singly resonant oscillator located within a Ti:sapphire laser cavity and analyzed by use of a steady-state model. Internal and external powers, circulating fields, tuning ranges, spectral bandwidths, and amplitude-stability levels are measured and discussed. The nonresonant idler tunes from 2.53 to 2.87 microm, delivers a maximum output power of approximately 0.4W and displays long-term amplitude-stable operation. The total downconverted power approaches the optimum power coupled out of the Ti:sapphire laser in the absence of frequency conversion.     

Continuous-wave Raman laser pumped within a semiconductor disk laser cavity

A KGd(WO?)? Raman laser was pumped within the cavity of a cw diode-pumped InGaAs semiconductor disk laser (SDL). The Raman laser threshold was reached for 5.6 W of absorbed diode pump power, and output power up to 0.8 W at 1143 nm, with optical conversion efficiency of 7.5% with respect to the absorbed diode pump power, was demonstrated. Tuning the SDL resulted in tuning of the Raman laser output between 1133 and 1157 nm.     

Sub-nanosecond microchip laser with intracavity Raman conversion

Efficient sub-nanosecond pulse operation of microchip lasers with intracavity Raman conversion and pulse compression is presented for the first time. The microchip lasers were composed of Nd:LSB or Nd:YAG laser crystals, Cr⁴⁺:YAG saturable absorber, and Ba(NO₃)₂ Raman medium. The pulse duration obtained at the Stokes wavelength (1196 nm) was as short as 118 ps. Optical conversion efficiency of laser-diode pump power to the Stokes power of 8% was reached. Pulse energy and peak power of Stokes emission were 1.2 μJ and 5.4 kW, correspondingly. Numerical calculations are in good agreement with obtained experimental results. Received: 20 December 2002 / Revised version: 6 March 2003 / Published online: 5 May 2003 RID="*" ID="*"Corresponding author. Fax: +1-716/645-6945, E-mail: ankuzmin@acsu.buffalo.edu RID="**" ID="**"Present address: University at Buffalo, SUNY, The Institute for Lasers, Photonics, and Biophotonics, 458 NSC, Buffalo, NY 14 260-3000, USA     

Continuous-wave Raman laser in H(2)

Recent developments in high-finesse cavities now make broadly tunable, continuous-wave Raman lasers possible. The design and preliminary characterization of what is to the authors' knowledge the first continuous-wave Raman laser in H(2) are presented. The threshold is currently at 2 mW of pump, making diode laser pumping possible. The maximum photon conversion efficiency observed was 35% at 7.6 mW of pump power.     

Threshold characteristic of intracavity optical parametric oscillator pumped by all-solid-state Q-switched laser

We derive the threshold pump intensity for a singly resonant intracavity optical parametric oscillator (IOPO)based on a temporal coupled field model.Particular attention is Paid to the dependence of the intracavity singly resonant OPO(SRO)threshold intensity on the signal wave output coupling.Meanwhile,a Nd:YAG laser pumped KTiOPO4(KTP)IOPO for eye-safe laser output is studied experimentally.The experiment is performed with four signal wave output reflectivities of 60%,70%,80%,and 90%,respectively.The measured values are in good agreement with the theoretical results.With an output coupler reflectivity of 80%,a peak power of 70 kW at 1572 nm has been obtained at a repetition rate of 3.5 kHz.The pulse width is 4.9 ns.Such investigation is helpful to identifying suitable operational regime of low pump intensity.     

Continuous-wave rotational Raman laser in H(2)

A diode-pumped, far-off-resonance cw Raman laser in H(2) with rotational Stokes emission is reported for the first time to our knowledge. The Raman laser can produce single-wavelength emission at either 830 nm (rotational Stokes) or 1180 nm (vibrational Stokes) depending on the frequency tuning of the pump laser. The mirrors for the rotational cw Raman laser are easier to produce; the laser also exhibits a wider continuous tuning range and is less sensitive to thermal effects than the previously studied vibrational Raman laser [Opt. Lett. 26, 426 (2001) and references therein].     

Raman oscillation with intracavity pumping of a fibre laser

We introduce the concept of cascaded resonant Raman pumping of fibre lasers. The pump scheme utilises the relatively large intracavity Stokes field that is generated within a Raman fibre laser to excite a lanthanide ion that is doped within the core of the fibre providing the Raman gain. In order to illustrate the general characteristics of the pump method and, to establish the design parameters necessary for the realisation of the pump scheme, calculations from a theoretical model that is used to simulate the generation of laser output from a fibre laser that is resonantly pumped with first Stokes radiation is presented. Specifically, the 2.1 μm output from a Ho³⁺-doped silica fibre laser that is pumped with 1.15 μm first Stokes radiation is calculated with the use of a relatively simple numerical model. For a launched pump power of 20 W at 1.07 μm, a fibre laser output of 3 W is predicted for a nominal intrinsic loss of 1.5 dB/km at 2.1 μm, however, this low value of the intrinsic loss at 2.1 μm can be significantly relaxed when the length of the Ho³⁺-doped silica fibre laser resonator is made considerably shorter than the Stokes resonator.     

Continuous-wave 560 nm light generated by intracavity SrWO4 Raman and KTP sum-frequency mixing

An LD end-pumped Nd:YAG/SrWO₄ continuous-wave 560 nm laser is presented based on intracavity sum-frequency mixing of the fundamental and first-Strokes light. The maximum output power of 330 mW at 559.6 nm was obtained for the diode pump power of 13.7 W and the conversion efficiency was about 2.5%. The intense blue emission was also observed in the SrWO₄ crystal when the Raman laser was operating above threshold. This blue emission is centered at 473 nm, which also happened to YVO₄.     

Continuous-wave intracavity frequency-doubled Nd:Yag-KTiOPO<Subscript>4</Subscript> red laser

Efficient and compact red laser output at 669 nm is generated by intracavity frequency doubling of a continuous-wave (CW) diode-pumped Nd:YAG laser at 1338 nm. With 16.9 W of diode pump power and the frequency-doubling crystal KTiOPO₄ (KTP), a maximum output power of 582 mW in the red spectral range at 669 nm has been achieved, corresponding to an optical-to-optical conversion efficiency of 3.4%; the output power stability over 4 h is better than 3.6%. To the best of our knowledge, this is first work on intracavity frequency doubling of a diode pumped Nd:YAG laser at 669 nm.     

Continuous-wave, intracavity optical parametric oscillators: an analysis of power characteristics

Received: 29 December 1997/Revised version: 6 February 1998     

Continuous-wave wavelength conversion for high-power applications using an external cavity diamond Raman laser

We demonstrate continuous-wave (cw) operation of a diamond Raman laser at 1240 nm in an external cavity configuration. The output power increased linearly with pump power with a 49.7% slope efficiency and reached 10.1 W at the maximum available pump power of 31 W. The combination of resonator design with diamond provides a novel approach to power-scalable cw wavelength and beam conversion.     

Continuous-wave green laser of 34 W by intracavity frequency doubling in diode-side-pumped Nd:YAG/KTP

Continuous-wave green laser with a maximum power of 34 W has been obtained by intracavity frequency doubling with KTP in diode-side-pumped Nd：YAG. The Nd：YAG/KTP green laser has a simple three- mirror V-fold cavity structure. The optical-to-optical conversion efficiency is 9.5%. The instability of the laser is measured when the output powers are near 16, 21, 30, and 34 W after the beam is filtered. At the maximum output power, the M^2 factor is measured to be 8.     

Continuous-wave,high-power,Raman continuum generation in holey fibers

The possibility of using low pump power for cw Raman continuum generation is demonstrated by optimization of the pump peak power and by accounting for the loss-related reduction of the effective length of Raman interaction in holey fibers. A 3.8-W, 324-nm-wide cw Raman continuum with a spectral power density higher than 10 mW/nm is generated in a completely fiber-integrated, single-mode format.     

Ultrafast all-solid-state laser technology

Passively mode-locked diode-pumped solid-state lasers can provide practical high-power laser sources with pico- and femtosecond pulse durations. We use semiconductors not only to optically pump but also to cw mode-lock or Q-switch a solid-state laser. A novel saturable absorber design, the Antiresonant Fabry-Perot Saturable Absorber (A-FPSA), allows of using semiconductor saturable-absorber materials even though they are generally not well-matched to the characteristics required for diode-pumped solid-state lasers, i.e., the semiconductors tend to have too much optical loss, a too low saturation intensity, and a too low damage threshold. This paper gives an overview of passively mode-locked ion-doped crystalline solid-state lasers. In particular, we present a quantitative discussion of A-FPSA mode locking, and compare A-FPSA mode locking with other passive mode locking techniques such as KLM (Kerr Lens Mode locking).     

Continuous-wave solid-state dye laser

We report the first realization of a cw solid-state dye laser. The laser medium consists of a laser dye (Rhodamine 6G) dissolved in a photopolymer. The UV-cured solution is sandwiched between two DVD substrates. The resonator design was derived from a conventional liquid solvent dye laser geometry. The laser radiation can be tuned from 565 to 615 nm by using a birefringent filter. A pump power of 2 W leads to a cw output power of more than 20 mW.     

All-solid-state 704 mW continuous-wave yellow source based on an intracavity, frequency-doubled crystalline Raman laser

Continuous-wave operation at 588 nm of a diode-pumped Nd:GdVO4 laser with intracavity Raman shifting [in KGd(WO4)2, KGW] and frequency-doubling (in LiB3O5, LBO) is reported. A maximum cw power at 588 nm of 704 mW was obtained for diode pump powers of 13.7 W. Quasi-cw yellow powers up to 1.57 W at a 50% duty cycle (to reduce thermal load in the laser crystal) indicate that power scaling to over 1 W is feasible.     

Continuous-wave, multiple-order rotational Raman generation in molecular deuterium

We demonstrate the generation of ≈10 rotational sidebands using continuous-wave stimulated Raman scattering in molecular deuterium. The generation occurs inside a high-finesse cavity at molecular gas pressures of ≈0.1?atm.