Fast Discharge Circuit for Longitudinally Excited CO2 Laser

In a longitudinally excited CO₂ laser with a short laser pulse, similarly to TEA and Q-switched CO₂ lasers, a fast discharge is very important. We investigated the use of a fast discharge circuit to obtain a high spike laser pulse in a longitudinally excited CO₂ laser. We compared a traditional capacitor-transfer circuit having a buffer capacitance of 700 pF with our direct-drive circuit in which the buffer capacitance is removed. The direct-drive circuit produced a fast discharge and a high spike laser pulse. We also investigated the effect of a resistance connected in parallel with the discharge tube to eliminate low discharge current after the main discharge. A low resistance of 1 kΩ or less acted as a shunt resistance. The shunt resistance was effective in decreasing the energy of the laser pulse tail at high gas pressure.     

Direct Laser Patterning of a 2D WSe2 Logic Circuit

Carrier doping is the basis of the modern semiconductor industry. Great efforts are put into the control of carrier doping for 2D semiconductors, especially the layered transition metal dichalcogenides. Here, the direct laser patterning of WSe₂ devices via light-induced hole doping is systematically studied. By changing the laser power, scan speed, and the number of irradiation times, different levels of hole doping can be achieved in the pristine electron-transport-dominated WSe₂, without obvious sample thinning. Scanning transmission electron microscopy characterization reveals that the oxidation of the laser-radiated WSe₂ is the origin of the carrier doping. Photocurrent mapping shows that after the same amount of laser irradiation, with increasing thickness, the laser patterned PN junction changes from the pure lateral to the vertical-lateral hybrid structure, accompanied by the decrease in the open circuit voltage. The vertical-lateral hybrid PN junction can be tuned to a pure lateral one by further irradiation, showing possibilities to construct complex junction profiles. Moreover, a NOR gate circuit is demonstrated by direct patterning of p-doped channels using laser irradiation without introducing passive layers and metal electrodes with different work functions. This method simplifies device fabrication procedures and shows a promising future in large scale logic circuit applications.     

Longitudinally Excited CO<Subscript>2</Subscript> Laser with Short Laser Pulse like TEA CO<Subscript>2</Subscript> Laser

We have developed a longitudinally excited CO₂ laser with a short laser pulse similar to that of TEA and Q-switched CO₂ lasers. A capacitor transfer circuit with a low shunt resistance provided rapid discharge and a sharp spike pulse with a short pulse tail. Specifically, a circuit with a resistance of 10 M Ω provided a spike pulse width of 103.3 ns and a pulse tail length of 61.9 μs, whereas a circuit with a shunt resistance of 100 Ω provided a laser pulse with a spike pulse width of 96.3 ns and a pulse tail length of 17.2 μs. The laser pulses from this longitudinally excited CO₂ laser were used for processing a human tooth without carbonization and for glass marking without cracks.      

Rapid Prototyping for Soft‐Matter Electronics

A series of rapid and inexpensive methods to produce elastically soft sensors and circuits in minutes using a CO₂ laser (10.6 μm wavelength) are introduced. These soft‐matter electronics are composed of laser‐patterned films of conductive poly(dimethylsiloxane) (cPDMS) and liquid‐phase gallium–indium (GaIn) alloy embedded in a thin sheet of soft silicone elastomer. Direct laser patterning eliminates the need for photolithography, replica molding, and customized inkjet or microcontact (μCP) printing, and allows conductive traces of cPDMS and liquid GaIn to be rapidly integrated into a single soft‐matter circuit. The versatility of this fabrication method is demonstrated by the production of a variety of electrically functional soft‐matter sensors and circuit elements that contain features with >150 μm planar dimensions. It is postulate that in the case of GaIn alloy patterning occurs when the recoil force of the escaping vapor exceeds the liquid's surface tension. This mechanism exploits the unique “moldability” of liquid GaIn alloy, which forms a surface oxide of Ga₂O₃ that allows the patterned film to maintain its shape.     

Relation Between Discharge Length and Laser Pulse Characteristics in Longitudinally Excited CO2 Laser

A longitudinally excited CO₂ laser pumped by a fast discharge emits a short laser pulse, similarly to TEA and Q-switched CO₂ lasers. We investigated the relation between the discharge length and the laser pulse characteristics to develop a longitudinally excited CO₂ laser producing a high spike laser pulse. We examined discharge lengths of 30, 45, and 60 cm, using the same mirrors and the same excitation circuit with the same input energy. A longer discharge length increased the discharge volume and improved the laser output energy. However, the longer discharge length caused a long discharge formation time (a slow fall time of the discharge voltage) due to the higher discharge impedance, which resulted in a long laser pulse tail. Therefore, the longitudinally excited CO₂ laser had optimum conditions for obtaining a high spike laser pulse effectively.     

A new stabilization system for optically pumped cw far infrared lasers

A new type of stabilization system for optically pumped far infrared (FIR) lasers based on a dual modulation technique is described, which enables to control the laser output power both as a function of the CO₂-laser pumping frequency and the FIR laser cavity length. The system greatly improves the laser output stability and causes only a negligible modulation (<1 %) of the output power. An additional feature, an electronic search circuit for emission lines, simplifies working at the laser even by ineperienced people.     

射频CO2波导激光器电源设计与调试

本文介绍小型全固体电路RF CO2波导激光器电源的设计和调试方法.该电源连续波工作时,工作频率f=120MHz,输出最大连续功率W=160W,脉冲工作时,调制频率fx=0～10kHz的方波连续可调,占空比连续可调.     

A 1.25 Gbps DC-coupled laser diode driver with VBE compensation technique

A 1.25 Gbps integrated laser diode driver (LDD) driving an edge-emitting laser has been designed and fabricated in 0.35 μm BiCMOS technology. The IC can provide independent bias current (5-100 mA) with automatic power control, and modulation current (4-85 mA) with temperature compensation adjustments to minimize the variation in extinction ratio. This paper proposed an unique modulation output driver configuration which is capable of DC-coupling a laser to the driver at +3.3 V supply voltage; and combined a V_BE compensation circuit, the IC can operate at a wide temperature range (−40 to 85 °C) for date rates up to 1.25 Gbps. V_BE compensation technique is used to compensate for variation in V_BE over the operating temperature range so as to minimize the variations in rise and fall time of modulation output over temperatures.     

激光打印机电源电路常见故障的检修

电源电路是激光打印机最容易出现故障的地方,文章首先介绍了激光打印机电源电路的特点,然后再详细分析了激光打印机开机无电故障以及高压电源电路部分故障的检修思路,最后给出了一些激光打印机常见故障的维修实例。     

TEA CO2激光器放电参数的计算及测量

本文针对Blumine型激励电路,对TEACO2激光器的充电过程、预电离过程和主放电过程的电路参数作了理论计算,并通过实验测量了这些参数。理论与实验很好地吻合。