The main goal of this work was to characterize the spectroscopic properties (absorption, fluorescence, and lifetime) of the samarium ion in the yttrium-aluminum-garnet matrix. The Sm:YAG crystals with various samarium concentrations (1, 3, 6.4, 10, and 20 at.% Sm/Y in the melt) were produced by the edge-defined, film-fed growth technique. Absorption characteristics were investigated in the spectral range of 185 - 3100 nm with detailed measurements in the near-infrared range of 1058 to 1125 nm, corresponding the energy level transition 6H5/2 → 6F9/2. The results indicate that the specific absorption properties of the Sm:YAG crystal could be advantageously used to an absorption of parasitic fluorescence around 1064 nm, generated by Nd:YAG laser. Concerning emission dependencies in a visible spectral region from 520 to 850 nm, a dominant peak was observed at 618 nm. In the infra-red spectral range from 850 to 1450 nm the dominant peak was found at the wavelength of 1231 nm. From the 4G5/2 level lifetime measurements, the dependence of lifetime on the samarium ions concentration in the YAG matrix was proven. Lifetime values ranged from 0.2 (20 at.% Sm/Y) to 2.0 ms (1.0 at.% Sm/Y). From the spectroscopic results it follows that the Sm:YAG crystal is a suitable candidate for attenuation of an unwanted spontaneous radiation at 1064 nm wavelength of the Nd:YAG laser or for lightconversion from UV to yellow-red visible region.
The concept of system for intracavity interferometry based on the beat note detection in subharmonic synchronously intracavity pumped optical parametrical oscillator (OPO) is presented. The system consisted of SESAM-modelocked, picosecond, diode pumped Nd:YVO4 laser, operating at wavelength 1.06 μm and tunable linear intracavity pumped OPO based on MgO:PPLN crystal, widely tunable in 1.5 μm able to deliver two independent trains of picosecond pulses. The optical length of the OPO cavity was set to be exactly twice the pumping cavity length. In this configuration the OPO produces signal pulses with the same repetition frequency as the pump laser but the signal consists of two completely independent pulse trains. For purpose of pump probe measurements the setup signal with half repetition rate and scalable amplitude was derived from the OPO signal using RF signal divider, electropotical modulator and fiber amplifier. The impact of one pump beam on the sample is detected by one probing OPO train, the other OPO train is used as a reference. The beat note measured using the intracavity interferometer is proportional to phase modulation caused by the pump beam. The bandwidth of observed beat-note was less than 1 Hz (FWHM), it corresponds to a phase shift measurement error of less than 1.5 × 10-7 rad without any active stabilization. Such compact low-cost system could be used for ultra-sensitive phase-difference measurements (e.g. nonlinear refractive index measurement) for wide range of material especially in spectral range important for telecom applications.
Singly resonant optical parametric oscillators (OPO) are most promising approach to sensors in which two pulses circulate
independently in a cavity. The OPO should be pumped intracavity, not only to access the high intracavity power of the pump
laser, but also because the two signal pulses share the same mode. The first synchronously pumped OPO were pumped
intracavity by a mode-locked dye laser. Subsequent implementation with solid-state pump lasers has been plagued by a
tendency to Q-switching, as well as competition between the two pulses generated in the signal cavity. In this contribution
we report the improved and optimized experimental setup of an intracavity synchronously pumped OPO based on a
periodically poled LiNbO3 crystal (PPLN) and of the pumping resonator of passively mode locked Nd:YVO4 laser from the
point of view of achievability of stable mode-locking and compensation of the astigmatism caused by Brewster angle cut
PPLN. This resulted in higher conversion efficiency due to the good overlap of pump and signal beam.
The goal of our work is the development of intracavity synchronously pumped optical parametrical oscillator
(OPO), generating two trains of picosecond pulses inside a single cavity. These trains have the same repetition
rate but they are independent and can differ in phase and carrier frequency. They can interfere on a detector,
producing a beat note at the carrier frequency difference. This allows to determine very precisely the phase
difference between them which is possible to use in all sensor applications where the measured physical quantity
is converted into phase difference between two counter-circulating pulses. We designed a synchronously pumped
OPO with nonlinear crystal (MgO:PPLN) for parametric generation inserted inside a linear resonator of a modelocked
diode pumped Nd:YVO4 laser. This configuration ensures the same way for signal and pumping waves
through the crystal and reduces the dead-band of the beat signal. We observed that the OPO could generate in
three regimes: the desired dual pulse operation when the pump pulse produces parametric waves during both
forward and return passes through PPLN crystal. Two single pulse OPO operations are possible when parametric
interaction occurred only during one pass of the pump pulse through the PPLN crystal in forward or backward
direction.
The motivation of this work is the development of a laser sensor and gyroscope based on short pulse solid state
ring laser. In comparison with regular ring laser containing the gain medium and saturable absorber where
counterpropagating pulses overlap, a ring synchronously pumped optical parametric oscillator (OPO) where the
pulse crossing point is controlled externally by the arrival time of the pump pulses is the ideal source for short
pulse laser sensor. The optimum configuration is OPO synchronously pumped inside the resonator of mode-locked
solid state laser. The operation of a picosecond synchronously intracavity pumped optical parametric oscillator
(OPO) is reported. A magnesium doped lithium niobate crystal (MgO:PPLN), periodically poled, is used as the
optical parametric oscillator crystal coupling the pump and the resonant signal cavities. The active medium of
the passively mode-locked pump cavity is a diode pumped Nd:YVO4 crystal. Continuous mode-locked operation
was achieved, tunable from 1531 to 1554nm by adjusting the OPO crystal temperature from 31 to 56 °C. The
spectral width of the generated radiation was 2 nm.
The operation of picosecond synchronously intracavity pumped optical parametric oscillator (OPO) is reported.
Singly resonant OPO is based on a Brewster cut single grating periodically poled magnesium doped lithium
niobate crystal(MgO:PPLN) pumped inside the resonator of a diode pumped passively mode-locked Nd:YVO4
laser. Continuously mode-locked operation was achieved, and tuning of signal wave wavelength in the range 1531
- 1554nm was observed for PPLN temperature variation from 31 to 55 ° C. Spectral width of the generated
radiation was 2 nm.
Results of experimental investigation of diode pumped Nd:YVO4 laser passively mode locked using either second
harmonic nonlinear mirror or semiconductor saturable absorber are reported. As an active element the 5mm long Nd:YVO4 crystal end pumped by 20 W fiber coupled laser diode was used. The linear folded resonator has on the other end either saturable absorber with single 15 nm thick In 0.25 Ga0.75 As quantum well layer integrated on the top of Bragg mirror (SESAM) either nonlinear mirror (NLM) consisting of a dichroic dielectric mirror and 10 mm long type I LBO crystal critically phase matched for second harmonic generation. Using the nonlinear mirror the threshold for mode locked operation was 10 W of pump power and we obtained 4.5 W of output power with single pulse duration of 6.2 Ps
for pump power of 15 W. Using the SESAM the pulse duration of 13-16 ps was achieved for pump power from 3W to 18 w for low output coupling.
The motivation of this work is the development of laser sensor and gyroscope based on short pulse solid state ring laser. In comparison with regular ring laser containing the gain medium and saturable absorber, where counterpropagating pulses overlap, a ring synchronously pumped optical parametric oscillator, in which the pulse crossing point is controlled externally by the time of arrival of the pump pulses, is the ideal source for short pulse laser sensor. The optimum configuration is a synchronously pumped parametric oscillator inserted inside the optical resonator of the diode pumped mode-locked solid state laser. We are developing a such system, as a first step we have demonstrated operation of a diode pumped Nd:YVO4 passively mode-locked laser using semiconductor saturable absorber with synchronously pumped intracavity optical parametric oscillator in linear configuration. The repetition rate of the pump laser was 132 MHz and the pulse duration of 15 ps. Parametric oscillator was based on 20 mm long Brewster cut single grating (with poling periode of 30.3 μm) periodically poled magnesium doped lithium niobate (MgO:PPLN) crystal. The temperature tuning of parametric luminescence from the crystal with peak wavelength at 1537 nm - 1550 nm for temperature variation from 30 °C to 57 °C was observed.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.