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Laser Transmitters: Coherent and Direct Detection
Published in Hamid Hemmati, Near-Earth Laser Communications, 2020
Often, optical output power, bandwidth, frequency, and noise behavior are key criteria for selecting a transmitter architecture. In particular, for use onboard the satellite and on certain airborne platforms, transmitter's overall efficiency is a key determinant in a transmitter's architecture. Wall-plug efficiency is the ratio of the optical output power produced by the transmitter and the required input electrical power consumption. For satellites and HAPs, dissipation of the thermal load generated by a high-power laser transmitter could become a major issue. That is another reason to pay close attention to the overall efficiency of the transmitter module. Additional accommodation efforts are involved if a thermal link to the platform or a special-purpose radiator is required.
Vertical Cavity Surface Emitting Laser
Published in Kenichi Iga, Yasuo Kokubun, Encyclopedic Handbook of Integrated Optics, 2018
where Vb is a bias voltage and the spontaneous component has been neglected. In the case of a surface emitting laser, the threshold current can be very small, and therefore the power conversion efficiency can be relatively large, that is, higher than 50%. The power conversion efficiency is sometimes called the wall-plug efficiency. However, at the high injection levels of actual devices, the heat generated in or near the active region forces the threshold to increase, and the power output to saturate, showing a so-called roll-off in current-output characteristic.
Understanding multi-domain compact modeling of light-emitting diodes
Published in Cogent Engineering, 2021
LEDs are semiconductor diodes with pn junction, as seen in Figure 1, on application of forward bias voltage , forward current flows, as a result, radiative electron-hole recombination occurs at the junction resulting in the emission of electromagnetic radiation in the form of radiant flux from the junction. Not all the electrical power is converted into electromagnetic radiation, a major portion of electron-hole recombination is non-radiative and needs to be dissipated away from the junction in the form of heat, represented as and depends on the LED material efficiency in converting applied electrical power into light or optical power . Wall-plug efficiency or radiant efficiency is the energy conversion metric with which the LEDs or LED products convert electrical power into radiant flux. It is defined as the ratio of the radiant flux to the input electrical power and represented by .
High-brightness 808 nm semiconductor laser diode packaged by SiC heat sink
Published in Journal of Modern Optics, 2020
Xingyu Li, Kai Jiang, Zhen Zhu, Jian Su, Wei Xia, Xiangang Xu
All models in the simulation are built according to the actual size. The size of the laser chip is 4 mm × 0.5 mm × 0.105 mm with strip width 100 µm. The output power of the laser is 15 W in CW and its wall-plug efficiency is 55%. The heat sink size is 5.9 mm × 4.5 mm × 0.4 mm. The structural layers of the two heat sinks are listed in Tables 1 and 2 in order from top to bottom. Considering that the thermal expansion coefficient and Young's modulus of SiC and AlN materials are different, in order to match the coefficient of thermal expansion (CTE), submount materials and metallization layers adopt different thickness ratios in the two heat sinks [8]. Metallization layers also block the downward diffusion of solder and facilitate wire bonding.
Compact turnkey system for multi-contact diode lasers for portable spectroscopic applications
Published in Instrumentation Science & Technology, 2023
Bernd Sumpf, Lucas Wittenbecher, Thomas Filler, Daniel Bandke, Maria Krichler, André Müller, Kay Sowoidnich, Arnim Ginolas, Ulrike Winterwerber, Martin Maiwald
The wall-plug efficiency of the system is dependent on the difference between the supply voltage of the driver and the operation voltage of the laser as the excess power is dissipated in the form of heat. To design the power supply of the turnkey system to maintain flexibility and at the same time maximize the efficiency and minimize the heat to be dissipated, the current sources are supplied with switched voltage sources. For this purpose, the current sources are divided into two banks suitable for 4 and 6 injection currents, respectively, which are each connected to a switched voltage source (TPS54622RHLR, Texas Instruments[12]).