FAQS - What is a LASER?

An acronym for Light Amplification by the Stimulated Emission of Radiation. A coherent, monochromatic light source having the common characteristics of an active material to convert energy into laser light, a pumping source to provide energy or power, optics to direct the beam repeatedly through the active material so that it becomes amplified, and the optics to direct the beam into a narrow cone of light

What is a laser diode / diode laser?

A laser made from a semi-conductor material, and powered by applying an electrical potential to the material.

more information

If you need any other questions answered, please email our technical engineers - sales@photonic-products.com or visit Sam's Laser FAQ

Q. What is MQW structure?

A.  In MQW (multi quantum well) structure, the active layer of the laser diode is a laminated structure comprising quantum well layers and barrier layers with a thickness of several nm. By regulating the composition of the quantum well layers that constitute the light emitting area, and using a crystal with a smaller lattice constant than the substrate, tensile stain is introduced into the quantum well layers. The band structure varies due to this strain, resulting in a lower threshold current and higher slope efficiency.

Q. What is the coherence length?

A. Most laser diode manufacturers do not measure this parameter. Typically, laser diodes are index-guided devices with 3x1µm emitting dimensions. Coherence length is approximately several centimetres.

Q. Is it single mode / single frequency?

A. Most laser diodes have a single mode structure with typical emitting dimensions of 3x1µm. However, Fabry Perot cavity laser diodes will mode hop, are sensitive to back reflections and may have regions in the power / current curve that are multi mode. So, yes, they are single mode / single frequency, but they will mode hop and may have multi mode operating regions.

Q .What is the maximum modulation bandwidth?

A. Typically 5.6mm and 9mm packaged laser diodes have a modulation bandwidth in excess of 500 MHz

Q. Can the laser be pulsed?

A. Yes, but the maximum CW power should be observed

Q. Can the laser be operated below -10°C?

A . Performance below -10°C has not been tested and is not recommended or guaranteed. It is likely that the laser will work but lifetime, optical and electrical performance will be reduced. Also the package may not remain hermetically sealed.

Q. Can laser diodes be wavelength selected.?

A. Yes they can, typically a ±3nm selection, subject to prior approval. A selection surcharge will be applied, details of which are available on request. Wavelength selection of devices in stock is possible at no surcharge. However, future availability of a particular wavelength cannot be guaranteed.

Q. Do you have laser diodes at wavelength X, power Y?

A. If the requested wavelength and / or power is not on the website, then please contact us to discuss your requirements.

Q. Do you offer DFB or DBR laser diodes?

A. We stock 1310nm and 1550nm DFB laser diodes.

Q. Do you offer telecomms diodes ?

A. Typically telecomms diodes are 1300nm, 1550nm or 980nm and they may be DFB or DBR structures.We stock a range of 1310nm, 1550nm Fabry Perot and DFB laser diodes for telecommunications.