Single Bars Diode Laser

Cooling mechanism
‌Water cooling‌: Laser water cooling is to dissipate heat through water circulation. The water is circulated inside and outside the laser to transfer heat to the water, and then recycled after dissipation in the radiator. Water cooling has high thermal conductivity and heat transfer capabilities, and can transfer heat to the outside faster, thereby ensuring efficient and stable operation of the laser and reducing the failure rate‌.

‌Conduction cooling‌: Conduction cooling usually refers to the use of the thermal conductivity properties of materials such as metals to dissipate heat. This cooling method depends on the thermal conductivity efficiency of the material and is usually used for small devices or local heat dissipation‌.

Applicable scenarios
‌Water cooling‌: Suitable for scenarios that require long-term continuous operation and ensure stability. Water cooling can provide better heat dissipation effect and reduce failure rate. It is suitable for high-power lasers or applications that require high stability‌.
‌Conduction cooling‌: Suitable for small devices or local heat dissipation needs. Since conduction cooling depends on the thermal conductivity efficiency of the material, its heat dissipation effect is relatively limited, and it is suitable for devices with low power or low heat dissipation requirements‌.

Maintenance cost and difficulty
Water cooling: requires regular replacement of scale filters and addition of coolant, which has high maintenance costs.
Conduction cooling: relatively simple maintenance, requiring only regular cleaning of heat dissipation components, and low maintenance costs.

CW working mode
The CW working mode means that the laser operates in a continuous manner, and the energy of the output beam remains constant and uninterrupted. This working mode is suitable for applications that require stable laser energy, such as fiber optic communications and material processing. The output power of CW lasers is relatively low, but it can remain stable, which is suitable for scenarios that require continuous output of laser energy. ‌

QCW working mode
The QCW working mode means that the laser operates in the form of pulses, the duration (width) of each pulse is limited, and there is a certain interval between pulses. QCW lasers usually emit pulses repeatedly at a high frequency, and the pulse width can be modulated as needed to control the output power and pulse energy of the laser. This operating mode is suitable for application scenarios with high requirements for time resolution, such as radar systems and medical equipment. The high-energy short pulses of QCW lasers can provide precise measurement and treatment effects. ‌

Specific application scenarios
‌CW working mode‌: Suitable for applications that require stable laser energy, such as fiber optic communications and material processing. In these applications, CW lasers can provide stable output power to meet the continuous needs of signal transmission or material processing.
‌QCW working mode‌: Suitable for applications with high requirements for time resolution, such as radar systems and medical equipment. The high-energy short pulses of QCW lasers can provide precise measurement and treatment effects.

The main functions of the CS laser bar with FAC lens include focusing the light, enhancing the directivity of the beam and reducing the divergence angle of the beam. ‌

The light emitted by a laser bar is already laser light itself, but because it is usually elliptical or coma-shaped when it emerges from the resonator, it requires a lens to focus it. The function of the lens is to focus these rays into a light point, thereby enhancing the directivity of the beam and reducing the divergence angle of the beam‌.

Focus Light
The lens can effectively focus the light emitted by the laser diode to form a light spot. This focusing effect can significantly increase the projection distance and brightness of light, making the application of laser diodes more efficient and practical‌.

Enhance the directivity of the beam
By focusing through the lens, the beam emitted by the laser diode can be more concentrated and more directional. This means that the beam can propagate in a specific direction more accurately, reducing the scattering and diffusion of the beam and improving the transmission efficiency of the beam‌.

Reduce beam divergence angle
The use of lenses can significantly reduce the divergence angle of the beam emitted by the laser diode. The reduced divergence angle means that the beam can maintain a smaller spread during propagation, thereby improving the collimation and stability of the beam‌.

The ‌laser beam smile effect‌ refers to the fact that in a semiconductor laser array (LDA), due to the thermal stress introduced during the packaging process, the laser chip produces light-emitting bending in the fast axis direction, causing the light spots of each light-emitting unit to not be in a straight line. This phenomenon is known as the “smile” effect‌.

Cause
The main cause of the "smile" effect is the mismatch in thermal expansion coefficient between the laser chip and packaging materials such as substrate heat sink during the packaging process, resulting in thermal stress. This thermal stress is further aggravated when the laser is working, causing the laser chip to bend, thus affecting the linearity of the beam‌.

Influence
The "smile" effect has a significant impact on beam quality, which is mainly manifested in the deterioration of the linearity of the beam and the uniform distribution of light spots. This will increase the difficulty of beam collimation, shaping and fiber coupling, thereby affecting the overall performance of the laser.

Practical implications and solutions
In practical applications, the "smile" effect will affect the beam quality of high-power semiconductor lasers, especially in applications that require high-precision alignment. In order to reduce the impact of the "smile" effect, it can be improved by optimizing the packaging process, using materials with a more matching thermal expansion coefficient, and considering the impact of temperature changes on beam quality in the design.

MCC laser diode bars can be packaged into laser diode stack. ‌

MCC laser diode bars can be packaged into laser diode stack by vertical stack (V-stack). Vertical stack semiconductor lasers overcome the beam quality problem of horizontal array lasers, and their beam quality is consistent with that of a single laser beam, which is suitable for applications with high beam quality requirements‌. In addition, with the improvement of packaging technology, the number of laser bars in a vertically stacked laser can be increased from a few to 70, and the maximum output power can also reach KW.

Packaging structure
The packaging structure of MCC laser diode bars generally includes a cathode, an anode, a coolant inlet and outlet. The coolant inlet of the coolant is close to the anode of the laser array, while the coolant outlet is close to the cathode‌. This structure enables MCC laser diode bars to effectively dissipate heat and manage heat when stacked in an array.

Application scenarios
After packaging into laser diode stack, MCC laser diode bars can be applied to a variety of high-power laser demand scenarios, such as industrial processing, scientific research, medical equipment, etc. Due to their high power output and good beam quality, MCC laser diode bars can meet the high requirements for laser equipment in these fields after being packaged.