Litcius/Paper detail

Single-longitudinal-mode-operated, passively Q-switched Nd:YAG/Cr<sup>4+</sup>:YAG microchip laser with &gt;100  kHz repetition rate and &lt;400  ps pulse width

Tao Chen, Xin Chen, Chenglin Zhou, Ming Li, Rong Shu

2020Applied Optics17 citationsDOI

Abstract

We report a comprehensive design procedure for passively <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mi>Q</mml:mi> </mml:math> -switched monolithic <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mtext>Nd</mml:mtext> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mo>:</mml:mo> </mml:mrow> <mml:mtext>YAG</mml:mtext> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mo>/</mml:mo> </mml:mrow> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:msup> <mml:mtext>Cr</mml:mtext> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mn>4</mml:mn> <mml:mo>+</mml:mo> </mml:mrow> </mml:msup> </mml:mrow> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mo>:</mml:mo> </mml:mrow> <mml:mtext>YAG</mml:mtext> </mml:math> microchip lasers to realize operation conditions of the pulse repetition rate (PRR) <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mo>&gt;</mml:mo> </mml:mrow> <mml:mn>100</mml:mn> <mml:mspace width="thickmathspace"/> <mml:mtext>kHz</mml:mtext> </mml:math> and pulse width (PW) <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mo>&lt;</mml:mo> </mml:mrow> <mml:mspace width="thinmathspace"/> <mml:mn>400</mml:mn> <mml:mspace width="thickmathspace"/> <mml:mtext>ps</mml:mtext> </mml:math> , simultaneously. Crucial parameters including effective pump power and waist diameter of the pump laser, doping concentration and thickness of the Nd:YAG crystal, initial transmittance ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:msub> <mml:mi>T</mml:mi> <mml:mn>0</mml:mn> </mml:msub> </mml:mrow> </mml:math> ) of the <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:msup> <mml:mtext>Cr</mml:mtext> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mn>4</mml:mn> <mml:mo>+</mml:mo> </mml:mrow> </mml:msup> </mml:mrow> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mo>:</mml:mo> </mml:mrow> <mml:mtext>YAG</mml:mtext> </mml:math> crystal, as well as the reflectivity of the output coupler are all considered during the design process. Two single-longitudinal-mode-operated lasers are designed and constructed according to the numerical results. The lengths and doping concentrations of Nd:YAG for both microchips are optimized to be 0.5 mm and 2%, respectively. A PRR up to 170 kHz and PW of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mo>∼</mml:mo> <mml:mn>370</mml:mn> <mml:mspace width="thickmathspace"/> <mml:mtext>ps</mml:mtext> </mml:math> are measured under the pump power of 2.6 W for a microchip with <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:msub> <mml:mi>T</mml:mi> <mml:mn>0</mml:mn> </mml:msub> </mml:mrow> </mml:math> of 0.85. A slightly lower PRR of 118 kHz with a shorter PW of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mo>∼</mml:mo> </mml:mrow> <mml:mn>320</mml:mn> <mml:mspace width="thickmathspace"/> <mml:mtext>ps</mml:mtext> </mml:math> is also achieved under the same pump power for another microchip with <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:msub> <mml:mi>T</mml:mi> <mml:mn>0</mml:mn> </mml:msub> </mml:mrow> </mml:math> of 0.8. The related pulse energies for the two microchips are <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mo>∼</mml:mo> </mml:mrow> <mml:mn>2.1</mml:mn> <mml:mspace width="thickmathspace"/> <mml:mtext>µ</mml:mtext> <mml:mtext>J</mml:mtext> </mml:math> and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mo>∼</mml:mo> </mml:mrow> <mml:mn>1.8</mml:mn> <mml:mspace width="thickmathspace"/> <mml:mtext>µ</mml:mtext> <mml:mtext>J</mml:mtext> </mml:math> , respectively. To the best of our knowledge, these results are among the highest PRRs achieved for passively <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mi>Q</mml:mi> </mml:math> -switched <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mtext>Nd</mml:mtext> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mo>:</mml:mo> </mml:mrow> <mml:mtext>YAG</mml:mtext> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mo>/</mml:mo> </mml:mrow> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:msup> <mml:mtext>Cr</mml:mtext> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mn>4</mml:mn> <mml:mo>+</mml:mo> </mml:mrow> </mml:msup> </mml:mrow> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mo>:</mml:mo> </mml:mrow> <mml:mtext>YAG</mml:mtext> </mml:math> microchips with PWs <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mo>&lt;</mml:mo> </mml:mrow> <mml:mn>400</mml:mn> <mml:mspace width="thickmathspace"/> <mml:mtext>ps</mml:mtext> </mml:math> .

Topics & Concepts

OpticsMaterials scienceQ-switchingLaserPulse durationPulse-width modulationLongitudinal modeTi:sapphire laserPulse (music)Repetition (rhetorical device)OptoelectronicsLaser pumpingPhysicsPower (physics)PhilosophyDetectorQuantum mechanicsLinguisticsSolid State Laser TechnologiesAdvanced Fiber Laser TechnologiesLaser Material Processing Techniques