Frequently Asked Questions

 

The commercial and industrial adoption of laser diodes has grown rapidly in recent years.  Laser diodes’ unique combination of optical performance, electrical efficiency, compact form factor, and mechanical robustness enables applications that are difficult or impractical with LEDs, lamps, and many non-semiconductor laser sources.

1) High Radiance in a Compact Package

Laser diodes provide extremely high radiance (radiant flux per unit emitting area per unit solid angle) because their emission originates from a small active region and can be efficiently coupled into guided or free-space optical systems. As a result, high optical power can be delivered from very compact laser diode packages, ranging from single-emitter devices to multi-emitter diode bars and stacked modules. In practice, this high radiance enables efficient coupling into optical fibers, tight focusing, and high optical power density at the target which is important for industrial illumination, (optical pumping), materials processing, and biomedical instrumentation.

2) High Electrical-to-Optical Efficiency (Low Power Consumption)

Compared with many other coherent sources, laser diodes are highly power efficient. Typical drive voltages are only a few volts, and required current could be from milliamps to amps. Wall-plug efficiencies exceeding ~40% are common for many commercial laser diodes, which reduces operating cost and thermal management burden. Higher efficiency also translates to smaller heatsinks, simpler power supplies, and improved system portability.

3) Ruggedness and Reliability from Solid-State Construction

Laser diodes are semiconductor devices and therefore do not require fragile glass tubes, high-voltage excitation, or precision mirror alignment typical of gas lasers and many bulk solid-state lasers. With no free-space resonator alignment to maintain, laser diode systems can tolerate shock, vibration, and wide operating environments. Their small size and solid-state reliability also support long service lifetimes and easier integration into OEM instruments.

4) Narrow Spectral Output and High Coherence

Laser diodes inherently produce spectrally narrower output compared with broadband sources such as lamps and LEDs. Many diode lasers can be engineered or stabilized to operate at a single wavelength (or narrow linewidth), which is critical for spectroscopy, interferometry, holography, sensing, and efficient coupling into wavelength-selective optics. Their coherence also enables high-contrast interference effects and precise optical phase-based measurement techniques.

5) Tight Focusing and High-Power Density at the Target

Because laser diode emission can be spatially controlled and collimated, it can be focused to a near diffraction-limited spot with appropriate optics (depending on emitter geometry and beam quality). The achievable spot size scales with wavelength; shorter wavelengths enable smaller focused spots. This is a key reason why shorter-wavelength diode lasers (blue/violet) support higher areal data density in optical storage and enable high-resolution scanning and imaging.

6) High-Speed Direct Modulation

Laser diodes can be directly modulated by varying the drive current, enabling intensity modulation at very high speeds. This capability supports high-bandwidth optical communication links and fast optical encoding without requiring bulky external modulators. In many telecom and datacom implementations, direct modulation provides a compact, cost-effective route to high-frequency optical modulation.

7) System-Level Integration Advantages

Laser diodes integrate well with modern electronics and photonics packaging. They can be combined with integrated drivers, temperature control (TEC), photodiode feedback, fiber coupling, micro-optics, and wavelength stabilization elements in compact assemblies. This high level of integration reduces system complexity, improves repeatability, and accelerates product development for industrial and medical OEM platforms.

In summary: laser diodes stand out for their high radiance and efficiency, rugged solid-state construction, narrow spectral output, focusability, and high-speed modulation; making them a foundational light source for communications, sensing, imaging, and industrial photonics.

 

Most commonly used materials for semiconductor lasers are the III-V compounds. These are such as GaAs, AlGaAs, InGaAs and InGaAsP depending upon the desired lasing wavelength emission.
Recently, GaN/AlGaN and InGaN/AlGaN are  being used to achieve laser diode emission in the green blue and ultraviolet regions.
InGaN (indium-gallium-nitride) is used for direct green laser diode emission.
Blue Diode Lasers (blue semiconductor laser diodes) are typically fabricated out of aluminum gallium nitride (AlGaN) or aluminum indium gallium nitride (AlInGaN).
Violet 405nm laser diodes and 375 nm UV laser diodes are based on either gallium nitride or indium gallium nitride.

Threshold Current :  The lowest current at which lasing action takes place.

Operating Current : Ideal laser diode operating current

Operating Voltage : The voltage across the laser diode at the specified operating current.

Wavelength : The output wavelength can vary from sample-to-sample and due to temperature.

Radiation Angle : The beam divergence parallel (horizontal) and perpendicular (vertical) relative to the gain region of the laser diode.

Positional and Angular Accuracy : The tolerance in mounting of the laser diode chip.

Differential Efficiency : Once the current threshold has been exceeded, the incremental increase in output power with current is fairly linear, measured in mW/mA. However, it can vary widely from sample-to-sample and with changes in temperature.

Astigmatism : The difference in virtual point source of the parallel and perpendicular beams.

Laser Diode Monitor Current : Sensitivity of the monitor photodiode with respect to laser diode output power.

The most familiar range is the visible spectrum – ranging from the short violet wavelengths to the the long red wavelengths. Most humans can see between 400nm and 700nm. Beyond the range of our vision exist shorter wavelengths of ultraviolet light, and longer wavelengths of infrared light. The higher the frequency of a photon, the more energy it has. World Star Tech carries laser diodes ranging from the ultraviolet 375nm to the infrared 1064nm.

The output power of a laser is the maximum power of the light exiting the the laser housing. All World Star Tech lasers have their output power rated after passing through any installed optical assemblies. The power is measured according to CDRH specifications.

Each laser is classified by measuring the amount of optical power that would enter a 7mm aperture located at a distance of 20cm from the laser source. Our line lasers have a lower classification rating because the laser power is spread along the length of the line, rather than focusing on a single small point.

Typical lifetime of laser diode modules are 25,000 to 50,000 hours. If the laser diode temperature rises beyond the maximum operating temperature the long-term performance may degrade significantly, up to and including complete failure. If the laser diode’s operating temperature is reduced by about 10 degrees, the lifetime will statistically double.

Laser module lifetime can be extended significantly by maintaining the case temperature at the low end of the operating temperature range. Heat sinks are recommended and must be used if the laser is operating constantly. Operating the laser modules at the low end of the recommended voltage range will also help to extend the lifetime of the laser.

The wavelength of a laser diode module shifts about 2 nm with every 10 degree rise in laser diode temperature.

Yes, TTL series lasers can be operated in CW mode. For CW operation, just connect the white TTL wire to the red positive voltage wire.

Boresight accuracy known as pointing accuracy, it is a measure of the angular difference between the beam propagating axis (where the laser beam is pointing) and the mechanical axis (where the laser housing is pointing). Pointing stability is a measure of how much the beam alignment drifts over a period of time.

The direction of the output beam of a laser is subject to some beam pointing fluctuations, which can in some cases cause significant problems – e.g., when the beam must be coupled into a single-mode fiber, or when the beam must precisely hit a target at a large distance. For such reasons, a quantitative measure for the beam pointing stability can be of importance.

In a weapon boresighting system for aircraft and vehicles, an optical square is oriented to a fixed reference line on the vehicle and provides the directionality of a pair of orthogonally positioned of laser illuminated retroreflective catadioptric collimators attached to said optical square whose outputs are directed via one or more deviators or periscopes to a pair of retroreflective catadioptric receivers orthogonally attached to a second optical square positioned at the weapon to be boresighted, each said receiver imaging the laser on a position sensitive sensor, the outputs of the latter indicating the pitch roll and yaw condition at the weapon.

Beam divergence specifies how much a beam spreads out over distance. All our beam divergence specifications are full angle values. The beam divergence of an electromagnetic beam is an angular measure of the increase in beam diameter or radius with distance from the optical aperture or antenna aperture from which the electromagnetic beam emerges. The term is relevant only in the “far field”, away from any focus of the beam. Practically speaking, however, the far field can commence physically close to the radiating aperture, depending on aperture diameter and the operating wavelength.

Beam divergence is often used to characterize electromagnetic beams in the optical regime, for cases in which the aperture from which the beam emerges is very large with respect to the wavelength. That said, it is also used in the Radio Frequency (RF) regime for cases in which the antenna is operating in the so-called optical region and is likewise very large relative to a wavelength.

Beam divergence usually refers to a beam of circular cross section, but not necessarily so. A beam may, for example, have an elliptical cross section, in which case the orientation of the beam divergence must be specified, for example with respect to the major or minor axis of the elliptical cross section.