#
Efficient Dual-Wavelengths Continuous Mode Lasers by End-Pumping of Series Nd:YVO_{4} and Nd:GdVO_{4} Crystals and Speckle Reduction Study

^{*}

## Abstract

**:**

## 1. Introduction

## 2. Experiments

#### 2.1. Dual-Wavelength Laser Setup

_{0}) of 120 µm.

_{o}) was varied along the optical axis (in z direction) through the cavity, allowing for the control of the gain and pumping absorption efficiency of each crystal [17]. z

_{o}= 0 was defined as the input facet (or ${M}_{1}$) of $L{C}_{1}$. The pump absorption efficiency of each crystal was also controlled by altering the pumping wavelength (${\lambda}_{p}$) which was achieved by changing the temperature of the LD.

#### 2.2. Tri/Quad Wavelength Laser Setup

#### 2.3. The Speckle Contrast Imaging Configuration

## 3. Results and Discussions

#### 3.1. Dual Output Wavelengths

^{2}was factor < 1.2 for 1062.4 nm and 1063.7 nm.

#### 3.2. Tri and Quad Output Wavelengths Emission

^{2}factor was measured to be <2; it was obvious that the quality of the total output lasers from each case became worse.

## 4. Conclusions

## Author Contributions

## Funding

## Conflicts of Interest

## References

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**Figure 1.**Experimental setup used in the measurements: (

**a**) diagram for end pumping series crystals laser and (

**b**) schematic diagram for σ-π configurations.

**Figure 2.**Configuration of $L{C}_{1}$ and $L{C}_{2}$ in multi wavelength emission. (

**a**) A 3D configuration with a tilted angle of θ for ${M}_{2}$, and (

**b**) xy-view of the setup for tri output wavelengths emission with θ = 0.7 mrad and ∅ = 0 rad (left) and quad wavelengths emission (right) with θ = 0.7 mrad and ∅ = 0.78 rad.

**Figure 4.**(

**a**) and (

**b**) are the single (1063.7 nm) and dual-wavelength normalized emission spectrum respectively.

**Figure 5.**The measured output powers of 1062.4 nm (triangle up) and 1063.7 nm (dots) for σ-π configuration.

**Figure 6.**The measured output power versus pump power for σ-π configuration, where the total output power, output power for 1062.4 nm, and 1063.7 nm are represented by black dots, red triangle up, and blue square, respectively.

**Figure 8.**The measured (

**a**) total power for σ-π configuration, (

**b**) power of 1063.7 nm in σ- polarization, (

**c**) power of 1062.4 nm in π- polarization.

**Figure 10.**The speckle contrast ratio (SCR) as a function of normalized power (P

_{λ2}/(P

_{λ1}+P

_{λ2})).

**Figure 11.**The measured output spectrum of (

**a**) tri-wavelength emission at 1062.4 nm, 1063.6 nm, and 1064.6 nm, and (

**b**) quad-wavelength emission at 1062.3 nm, 1063.6 nm, 1064.5 nm, and 1066.1 nm.

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## Share and Cite

**MDPI and ACS Style**

Mohamed, M.; Zhang, B.; Ma, Q.; Kneller, J.; Xu, C.-Q.
Efficient Dual-Wavelengths Continuous Mode Lasers by End-Pumping of Series *Nd*:*YVO*_{4} and *Nd*:*GdVO*_{4} Crystals and Speckle Reduction Study. *Photonics* **2019**, *6*, 53.
https://doi.org/10.3390/photonics6020053

**AMA Style**

Mohamed M, Zhang B, Ma Q, Kneller J, Xu C-Q.
Efficient Dual-Wavelengths Continuous Mode Lasers by End-Pumping of Series *Nd*:*YVO*_{4} and *Nd*:*GdVO*_{4} Crystals and Speckle Reduction Study. *Photonics*. 2019; 6(2):53.
https://doi.org/10.3390/photonics6020053

**Chicago/Turabian Style**

Mohamed, Mahmoud, Bin Zhang, Qianli Ma, Josh Kneller, and Chang-Qing Xu.
2019. "Efficient Dual-Wavelengths Continuous Mode Lasers by End-Pumping of Series *Nd*:*YVO*_{4} and *Nd*:*GdVO*_{4} Crystals and Speckle Reduction Study" *Photonics* 6, no. 2: 53.
https://doi.org/10.3390/photonics6020053