Laser Diode Electronics

Electronics Circuit Question-------How to prevent VOLTAGE SPIKES and get CONSTANT CURRENT in a circuit?

I have a very sensitive laser diode that will be run on about 150mw and 200ma. I plan to run it on a rechargable AAA battery. To step the current down to a useable level, I plan to put a 3.75 to 4 Ohm resistor in series. There will be a switch that turns it on when pressed leading to the possibility to an increase in voltage or current.

HOW DO I AVOID THESE SPIKES with a electrical component(capacitor, inductor, ect) that will fit in the same size diameter as the AAA battery (about 10mm)? What size component would work in a circuit with a 850mah, 1.2v battery, and the 3.75(to 4) ohm resistor, and would it be in series or parallel.
To put a capacitor in series with a switch, how would it be across the switch? Wouldnt it be in parallel?
Also, what is the difference between putting it in parallel with the diode, and putting it in parallel with the switch?

You do not say how smooth you want the power-on ripple to be. But if you take the largest, say 6 or 10 volt electrolytic capacitor - you can use 4 or even 2.5 volt if you can find them - that you can comfortably fit into the space, and wire it in

YES ! Parallel! (In series with the circuit) Sorry! Sloppy of me.

across the switch, plus to plus, minus to minus, even a 10 mfd capacitor would be more than enough to protect the diode. With only a 4 ohm resistor, you will not observe any latent timing delays in switching on or off.

Any transients will be sharply muted because the capacitor will 'try' to oppose any change in voltage by absorbing charge or releasing its own stored charge, to the extent of the size of its capacitance, and so it acts like a sort of (physical) shock absorber.

Last time:If the diode capacitor is further away, the switch capacitor will end up smoothing the voltage a slightly more. the compensation is not quite instantaneous, and the propagation-time delay to the diode gives time for the voltage to settle (slightly) more. Considering your application the more usual advantage of suppressing any arcing across the switch contacts is not much of an issue. But in principle, yes, either - or even both - would give additional protection to the diode. Having a larger capacitor at he switch and then a much smaller one at the diode would give an improved result, with the larger damping the major part of transients, and the smaller, quicker capacitor, damping the much smaller spikes that get though.

You could also protect the diode using a zener diode in parallel with it, in the opposite polarity. You would pick a breakdown voltage that would protect the diode, and it would conduct current, effectively shorting out, whenever the voltage got too high, for as long as it was too high. But I have a vague recollection - that may not be correct - that zeners do not respond very quickly, and so there may be an issue here not allowing even brief transients.

Laser Diode Microsystems $301.11 Laser Diode Microsystems provides the reader with the basic knowledge and understanding required for using semiconductor laser diodes in optical microsystems and microoptical electromechanic systems. This tutorial addresses the fundamentals of semiconductor laser operation and design, coupled with an overview of the types of laser diodes suitable for use in Microsystems, along with their distinguishing characteristics. Emphasis is placed on laser diode characterization and measurement as well as the assembly techniques and optical accessories required for incorporation of semiconductor lasers into complex microsystems. Equipped with typical results and calculation examples, this handon text helps readers to develop a feel for how to choose a laser diode, characterize it and incorporate it into a microsystem. Author: Zappe, Hans P./ Zappe, H. Series Title: Microtechnology and Mems (Hardcover) Binding Type: Hardcover Number of Pages: 355 Publication Date: 2003/10/10 Language: English Dimensions: 9.21 x 6.14 x 0.81 inches

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CET Domain 10021910 Playstation 3 Compatible Laser Diode $72.83 Replace your damaged laser diode built for Playstation 3 KEM400AAA and KES400AAA laser lenses. Use and replace your laser diode with precaution. All laser diodes are extremely ESD sensitive. Compatible Models: Playstation 3 compatible KEM400AAA and KES400AAA laser lenses (sold seperately). Note: Installation guide is not included' please look for it online or use the help of an accreditate technician. We will not be responsible for any damage of your device due to improper installation. This item takes between 721 days to ship/arrive because it ships out of Hong Kong or China.

Cet 10021911 Playstation 3 Compatible 410 Series Laser Diode $46.28 Replace your damaged laser diode built in your PlayStation 3 KEM410 and KES410 laser lens. Use and replace your it with precaution as this laser diode is very fragile and extremely ESD sensitive. Compatible Models: Playstation 3 compatible KEM410 and KES410 laser lenses (not included). Note: Installation guide is not included' please look for it online or use the help of an accreditate technician. We will not be responsible for any damage of your device due to improper installation. This item takes between 721 days to ship/arrive because it ships out of Hong Kong or China.

Simulation of Ingan Blue Laser Diode $172.06 In this book, the design of InGaN LDs structures including multi quantum wells (MQWs) active region device are described and investigated by integrated system engineering technology computer aided design (ISE TCAD) device simulator. The parameters of the LDs structures are varied and optimized for high performance. This optimization study involves aspects such as thickness of active region, doping, thickness of stopper layer region, thickness of quantum wells and quantum barriers, number of quantum wells and several approaches to improve and achieve high efficiency, low threshold current and high output power of InGaN LDs. The basic LDs structures treated here are FabryPerot type InGaN double heterostructure (DH), separate confinement heterostructure (SCH) and multi quantum wells (MQWs).High performance LD has been obtained by using multi quantum wells incorporated with the optimized parameters. The lowest threshold current, higher external quantum efficiency and characteristic temperature are obtained when the number of InGaN well layers is two, at our laser emission wavelength of 415 nm, which is related to the problem of inhomogeneous carrier. Author: Thahab, Sabah Binding Type: Paperback Number of Pages: 232 Publication Date: 2011/01/31 Language: English Dimensions: 5.98 x 9.00 x 0.53 inches

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Sticky Light - the smart laser scanner revisited

NEED A GREAT HELP IN ELECTRONICS?

actually what factors that determine the wave length of emission in LED [light emission diodes] and laser devises ????

very much thankful to u if u provide some details on that

Conventional LEDs are made from a variety of inorganic semiconductor materials, the following table shows the available colors with wavelength range, voltage drop and material:

Color Wavelength [nm] Voltage [V] Semiconductor Material
Infrared λ > 760 ΔV < 1.9 Gallium arsenide (GaAs)
Aluminium gallium arsenide (AlGaAs)
Red 610 < λ < 760 1.63 < ΔV < 2.03 Aluminium gallium arsenide (AlGaAs)
Gallium arsenide phosphide (GaAsP)
Aluminium gallium indium phosphide (AlGaInP)
Gallium(III) phosphide (GaP)
Orange 590 < λ < 610 2.03 < ΔV < 2.10 Gallium arsenide phosphide (GaAsP)
Aluminium gallium indium phosphide (AlGaInP)
Gallium(III) phosphide (GaP)
Yellow 570 < λ < 590 2.10 < ΔV < 2.18 Gallium arsenide phosphide (GaAsP)
Aluminium gallium indium phosphide (AlGaInP)
Gallium(III) phosphide (GaP)
Green 500 < λ < 570 2.18 < ΔV < 4.0 Indium gallium nitride (InGaN) / Gallium(III) nitride (GaN)
Gallium(III) phosphide (GaP)
Aluminium gallium indium phosphide (AlGaInP)
Aluminium gallium phosphide (AlGaP)
Blue 450 < λ < 500 2.48 < ΔV < 3.7 Zinc selenide (ZnSe)
Indium gallium nitride (InGaN)
Silicon carbide (SiC) as substrate
Silicon (Si) as substrate — (under development)
Violet 400 < λ < 450 2.76 < ΔV < 4.0 Indium gallium nitride (InGaN)
Purple multiple types 2.48 < ΔV < 3.7 Dual blue/red LEDs,
blue with red phosphor,
or white with purple plastic
Ultraviolet λ < 400 3.1 < ΔV < 4.4 diamond (C)
Aluminium nitride (AlN)
Aluminium gallium nitride (AlGaN)
Aluminium gallium indium nitride (AlGaInN) — (down to 210 nm[27])
White Broad spectrum ΔV = 3.5 Blue/UV diode with yellow phosphor