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Applications of Ultrafast Lasers in the RF Field - 1
RF (Radio Frequency) technology is widely used in key fields such as communications, electronic manufacturing, national defense, and aerospace.
Its performance improvement has always relied on breakthroughs in core links such as material processing precision, signal generation efficiency, and device integration.
With its unique advantages of ultra-short pulse width (picosecond and femtosecond levels) and high peak power, ultrafast lasers have revolutionarily empowered traditional RF technology.
They have demonstrated irreplaceable application value in scenarios such as precision manufacturing of RF devices, remote RF signal generation, communication signal optimization, and high-end RF acceleration systems, driving RF technology toward higher frequency, higher precision, and lighter weight.
1. Precision Manufacturing of RF Devices: Breaking Through the Bottleneck of Heat-Sensitive Material Processing
The performance of RF devices is directly related to the quality of material processing.
Especially for ceramic materials such as Al₂O₃, AlN, and GaN, as well as sensitive two-dimensional materials such as graphene and organic films, traditional processing technologies are prone to thermal effects, leading to defects such as discoloration of material edges and microcracks, which seriously affect the signal transmission efficiency and stability of RF devices.
The "cold processing" characteristic of ultrafast lasers—energy only acts on the processed area with almost no thermal diffusion—perfectly solves this pain point.
In practical applications, professional high-precision picosecond laser systems (such as LPKF ProtoLaser R4) have become core equipment for RF R&D and manufacturing.
Such equipment can achieve a pulse width of up to 1.5 picoseconds and a repetition rate adjustment range of 50kHz-500kHz.
By precisely controlling the pulse energy (from below 1μJ to 80μJ), it can realize high-precision cutting of ceramic materials, fine etching of ultra-thin materials, and selective removal of metal layers on plastic film surfaces (such as removing DuPont ME614 metal layers on PC).
The Institute of Electronics, Communications and Information Technology (ECIT) at Queen's University Belfast has built an RF manufacturing laboratory with this equipment to carry out research on the RF characteristics of sensitive materials, providing core processing support for the R&D of high-performance RF devices.
In addition, the application of ultrafast lasers in the field of advanced RF packaging has become increasingly mature.
For example, the TGV (Through Glass Via) structure processed by femtosecond lasers on glass materials can have an aperture as low as 4.5 microns, a pitch of 6 microns, a roundness of more than 98%, and extremely high consistency.
This technology has been widely used in scenarios such as RF front-end modules and optoelectronic integration, effectively improving the miniaturization and integration of RF devices.
2. Remote RF Signal Generation: Opening Up a New Path for High-Power Microwave Applications
High-Power Microwaves (HPM, frequency 1-300GHz, peak power ≥100MW) have key demands in fields such as national defense anti-electronic jamming, space energy transmission, and remote propulsion.
However, traditional HPM equipment based on cathodes or capacitors has limitations such as large volume and severe remote transmission power attenuation.
Ultrafast lasers realize efficient generation of remote RF signals through laser-plasma interaction, providing a revolutionary solution to this problem.
Its core principle is: ultra-intense ultra-short pulse lasers can achieve long-distance (ground-to-space, space-to-space, or between two ground points) projection of high-intensity light (≈10¹³W/cm²) through laser filamentation.
Transient plasma is generated on the surface of remote target materials, and this plasma acts as a local RF radiation source to generate RF signals through mechanisms such as transient dipole radiation and resonance absorption.
Experiments have verified that this method can stably generate RF signals in the frequency band from single GHz to tens of GHz.
By matching microwave horn antennas with heterodyne electronic equipment, the spectral composition, angular distribution of RF emission, and the dependence of laser focusing conditions can be accurately characterized.
This remote RF generation technology does not require complex equipment deployment at the target end, effectively avoiding power loss in traditional RF transmission, and laying a foundation for cutting-edge applications such as remote energy transmission and soft kill interception of UAV swarms.
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What are the precautions for operating a laser marking machine?
1. It is strictly prohibited to start the laser power supply and Q-switching power supply when there is no water or the water circulation is abnormal.
2. The Q power supply is not allowed to operate without load (i.e., the output terminal of the Q power supply should be left floating).
3. In case of any abnormal phenomenon, first turn off the galvanometer switch and the key switch, and then conduct a check.
4. It is not allowed to start other components before the krypton lamp is lit to prevent high voltage from entering and damaging the components.
5. Pay attention to leaving the output terminal (anode) of the laser power supply suspended to prevent sparking and breakdown with other electrical appliances.
6. Keep the internal circulating water clean. Regularly clean the water tank and replace it with clean deionized water or pure water.
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What should we do when laser intensity decreases and the marking is not clear enough?
1. Turn off the machine and check if the laser resonant cavity has changed; Fine-tune the resonant cavity lens. Make the output light spot the best;
2. The acousto-optic crystal is offset or the output energy of the acousto-optic power supply is too low;
Adjust the position of the audio-visual crystal or increase the working current of the audio-visual power supply;
3. The laser entering the galvanometer deviates from the center: Adjust the laser;
4. If the current is adjusted to around 20A but the light sensitivity is still insufficient: the krypton lamp is aging. Replace it with a new one.
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How to maintain a UV laser cutting machine?
1. It is required to carry out regular cleaning every day, remove debris from the countertop, limiters and guide rails, and spray lubricating oil on the guide rails
2. The waste materials in the collection box should be cleared regularly to prevent excessive waste from blocking the exhaust port.
3. Clean the chiller once every 15 days, drain all the internal water, and then fill it with fresh pure water.
4. The reflector and focusing lens should be wiped with a special cleaning solution every 6 to 8 hours.
When wiping, use a cotton swab or cotton swab dipped in the cleaning solution to wipe from the center to the edge of the focusing lens in a counterclockwise direction.
At the same time, be careful not to scratch the lens.
5. The indoor environment can affect the lifespan of the machine, especially in damp and dusty conditions.
A damp environment is prone to causing rust on the reflective lenses and also easily leading to short circuits, discharge and sparking of the velvet laser.
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What accidents might be caused by the laser emission when using a laser cutting machine?
(1) A fire was caused by the laser coming into contact with flammable materials.
Everyone knows that the power of laser generators is very high, especially when it comes to high-power laser cutting machines, the temperature of the emitted laser is extremely high. The possibility of a fire being caused when a laser beam comes into contact with flammable objects is very high.
(2) Harmful gases may be produced when the machine is in operation.
For instance, when cutting with oxygen, it undergoes a chemical reaction with the cutting material, generating unknown chemical substances or fine particles and other impurities. After being absorbed by the human body, it may cause allergic reactions or discomfort in the lungs and other respiratory tracts. Protective measures should be taken when conducting work.
(3) Direct laser exposure to the human body can be harmful.
The damage caused by lasers to the human body mainly includes damage to the eyes and skin. Among the harms caused by lasers, the damage to the eyes is the most severe. Moreover, damage to the eyes is permanent. So when doing homework, you must pay attention to protecting your eyes.
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What is the focused spot diameter of nanosecond, picosecond and femtosecond laser?
Nanosecond: The light spot is 0.5-1mm.
Picosecond: The focused spot is around 0.02mm.
Femtosecond: Under the action of a laser beam with a high repetition rate of 100-200KHz and a very short pulse width of 10ps,
the focused spot diameter is as small as 0.003mm.
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What are the main applications of UV laser cutting machine?
The UV laser cutting machine can be used for cutting and depaneling PCB.
It can precisely cut and shape various types of PCB circuit boards with V-CUT and stamp holes, and open Windows and covers.
It can also be used for separating packaged circuit boards and ordinary smooth boards.
It is suitable for cutting various types of PCB substrates, such as ceramic substrates, rigid-flex boards, FR4, PCBs, FPCs, fingerprint recognition modules, cover films, composite materials, copper substrates, aluminum substrates, etc.
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Precautions for laser cutting machines to process various metal materials?
Copper and brass:
Both materials have high reflectivity and excellent thermal conductivity.
Brass with a thickness of less than 1mm can be processed by nitrogen laser cutting.
Copper with a thickness of less than 2mm can be cut. The gas used for laser cutting processing must be oxygen.
Copper and brass can only be cut when a "reflective absorption" device is installed on the system. Otherwise, reflection will damage the optical components.
Synthetic materials:
Processable synthetic materials include: thermoplastics, thermosetting materials and artificial rubber.
Aluminum:
Despite its high reflectivity and thermal conductivity, aluminum materials with a thickness of less than 6mm can be cut, depending on the type of alloy and the capacity of the laser.
When cutting with oxygen, the cutting surface is rough and hard.
When nitrogen is used, the cutting surface is smooth.
Pure aluminum is extremely difficult to cut due to its high purity.
Only when a "reflection and absorption" device is installed on the fiber laser cutting machine system can aluminum materials be cut.
Otherwise, reflection will damage the optical components
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What should be paid attention to when laser cutting stainless steel?
Laser cutting processing of stainless steel requires the use of oxygen, under the condition that edge oxidation is not a concern.
If nitrogen is used to achieve an edge free of oxidation and burrs, no further processing is required.
Coating an oil film on the surface of the sheet will achieve a better perforation effect without reducing the processing quality.