Deeper Dive into VCSEL Laser Technology
What is the difference between Laser Diodes and VCSELs?
Laser Diodes and VCSELs are semiconductor lasers, the simplest form of Solid State Lasers. Laser diodes are commonly referred to as edge emitting laser diodes because the laser light is emitted from the edge of the substrate. The light emitting region of the laser diode is commonly called the emitter. The emitter size and the quantity of emitters determine output power and beam quality of a laser diode. These Fabry Perot Diode Lasers with a single emission region (Emitter) are typically called laser diode chips, while a linear array of emitters is called laser diode bars. Laser diode bars typically use multimode emitters, the number of emitters per substrate can vary from 5 emitters to 100 emitters. VCSELs (Vertical Cavity Surface Emitting Laser) emit light perpendicular to the mounting surface as opposed to parallel like edge emitting laser diodes. VCSELs offer a uniform spatial illumination in a circular illumination pattern with low speckle.
Why VCSELs for Laser Illumination Applications?
Vertical-Cavity, Surface-Emitting Lasers (VCSELs) are an ideal diode laser source for illumination applications due to an inherent uniform and circular beam emission. Due to the vertical emitting structure, the beam emits a symmetrically circular beam with narrow divergences in the ~20° range which provides a simple, elegant solutions for manipulating the beam. In addition, they produce low speckle imagery commonly seen with LED illumination. The uniform, speckle-free illumination from Vertical-Cavity, Surface-Emitting Lasers provides the end user with the high-resolution and quality currently lacking from typical edge-emitting laser diode illumination systems. Edge-emitting laser diodes can require complex optical solutions to address the speckle and the fast and slow axis divergences.
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What Role can VCSELs Play on the Frontline, Fighting COVID-19?
Our suppliers develop and manufacture VCSELs, providing 850/940nm VCSEL light sources to help meet the increased demand for high-quality pulse oximeters in the fight against COVID-19. We also provide PIN diode/Photodiode receiving pairs. We offer various wavelengths (808nm, 850nm & 940nm) and power options for our VCSELs, used as the core light emission source of pulse oximeters.
Compared to LEDs, VCSEL light sources enable more accurate measurements for oximetry applications, penetrating deeper into the skin. VCSELs provide the benefits of a narrower spectral linewidth emission, a 4X smaller shift in wavelength with temperature, and as much as an order of magnitude reduction in power consumption. The latter consideration is particularly relevant, considering the change to wireless sensors for patient convenience or home monitoring of patients with telemetric medicine.
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How are VCSELs Contributing to the Evolution of Solid-State LIDAR?
LIDAR is a critical component of ADAS (Advanced Driving Assisting System), AVs (Autonomous Vehicles), and industrial automation systems. Highly efficient VCSELs (vertical-cavity surface-emitting lasers), with their tiny footprint, attractive pricing, and remarkable reliability and performance, will undoubtedly have an increased positive effect on the LiDAR industry. 100% solid-state LiDAR systems show great potential as the next evolution in LiDAR technology, aiming to replace traditional bulky and expensive mechanical spinning and microelectromechanical systems (MEMs) LiDAR systems. RPMC Lasers is committed to providing the LiDAR industry with high-quality, reliable, and affordable VCSEL solutions.
Sharing the 100% solid-state LiDAR classification, Flash LiDAR and Optical Phase Array (OPA) LiDAR systems lack moving parts, minimizing the vibration effect. All components can be integrated onto a single board to reduce the size, increase performance, and improve ruggedness.
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Low Divergence VCSELs Solve the Pain Points of LIDAR and Laser Sensors
As we all know, a technical topic in ranging and LIDAR is how to improve the signal-to-noise ratio of laser detection, increasing LiDAR accuracy and sensing distance. Typically, the two options are to increase the laser power density or reduce noise (including detector noise and noise generated by ambient light). There are two main ways to increase power density: one is to minimize divergence; the other is to increase optical power. Boosting optical power increases power consumption, so it is preferable to reduce the divergence of laser, maintaining the same power consumption level. The traditional method to reduce divergence is usually by complex optical lens combination. However, it may result in a bulky, fragile, and expensive system.
Utilizing SMD packaging technology to encapsulate optical lensing on the VCSEL bracket greatly reduces product size. Users can accelerate product development without any unique optical design, saving R&D costs and time.
These VCSEL modules, with integrated collimating lens, and measuring only 3.5mm x 3.5mm x 3.5mm, can provide reduced divergence (FWHM) as low as 3-5 mrad. Presently, these VCSEL SMD modules are available in 808nm, 850nm, and 940nm, with small size, low divergence, and high peak power, effectively improving signal strength and significantly increasing the LIDAR detection range.
Compared to ~0.3 nm/K of edge-emitting lasers (EELs or traditional laser diodes), Vertical-Cavity Surface-Emitting Lasers (VCSELs) have a much smaller wavelength drift with temperature (~0.07 nm/K). These VCSELs do not require additional wavelength stabilization schemes or external optics, which is a must for EELs. In addition, due to the advanced technology of epitaxial growth and packaging, the wavelength of large-scale VCSEL 2D arrays is very uniform, with a spectral width of about 0.8 nm. This spectral width is significantly lower than that of edge emitters (3 ~ 5 nm). The narrow bandwidth characteristics allow VCSELs to match the specific absorption spectrum, conducive to reducing the interference of ambient light and improving the signal-to-noise ratio.
Regarding reliability, VCSELs have inherent advantages over edge-emitting lasers because VCSELs do not suffer from catastrophic optical damage, and their activation energy is almost twice that of edge-emitting lasers (~0.7 eV). This means that VCSELs can operate reliably at higher temperatures. This advantage is vital because VCSEL cooling requirements become less stringent, resulting in more compact laser systems and higher overall efficiency for high-reliability application scenarios such as automotive, aerospace, and more.
Low divergence light sources are also often used in the detection of some special-shaped or complex environments. To increase measurement distance and reduce malfunctions, the light source must emit a beam with a smaller angle. Optical lenses can be coupled with VCSEL to collimate the output beam, thereby reducing beam divergence.
Various TO Packaged VCSEL Diodes
As VCSELs are a surface-emitting laser chip like LEDs, SMD (Surface Mount Device) is its natural packaging form, and SMD packaging has many dominant advantages, such as good heat dissipation, easy mounting with electronic components, small size, etc. However, SMD packaging may cause deviation in alignment with optical components, most likely when matching with optical lens systems. So, in the laser industry, there is a pressing demand for TO packaging of VCSELs. TO-packaged VCSEL products are available with various wavelengths and optical powers for different product application scenarios.
Popular packages like TO46, TO56, and TOSA are available in 670nm, 808nm, 850nm, and 940nm wavelengths, mass-produced in both continuous-wave (CW) and pulsed VCSELs versions. In continuous-wave mode, optical power can reach up to 300mW, which has been used in laser modules, range finder sensors, 3D scanners, and other applications; In pulse mode and low duty cycle and nanosecond pulse, peak power can go from 10W to 100W, widely used in dTOF laser ranging finder sensor, 3D dTOF cameras, and lidars
To monitor VCSEL operating status, a photodiode can also be packaged together in TO46 and TO56 (optional according to user requirements).
In addition to TO packages, cost-effective, plastic-encapsulated dip VCSELs can replace plastic-encapsulated LEDs, as VCSELs have high power density and a higher SNR to ambient light interference – for low cost sensors such as proximity sensors and ranging finder sensors.
How to Efficiently Formulate Laser Modules
Laser modules can be configured with a wide range of wavelengths, power levels, and beam shapes. Laser modules have excellent optical characteristics, like high uniformity, high power density, durability and stability, high precision, and minimal size. They are ideal for machine vision, 3D scanning, indication, positioning, measurement, and other fields, used in Consumer Electronics, Life Sciences, and Industrial Applications.
Choosing an ideal laser module for a system is a complex task. To achieve the best performance, it is necessary to consider the operating environment, module size, durability, laser safety, and cost constraints. These elements are usually independent, but engineers must make various trade-offs and compromises between performance priority and cost constraints.
Below, we will introduce the critical considerations regarding how to efficiently and accurately formulate the laser module specifications required by the system and the best OEM laser module solutions.
Wavelength Selection
Wavelength is the core of any laser module design. Choosing a suitable laser source is the first step to achieving a successful design.
The human eye can respond to wavelengths between approximately 400 and 700 nm. Most vision applications use light in this range, but some require cameras sensitive to the infrared or ultraviolet spectrum. Many CCD or CMOS-based machine vision cameras can detect light up to about 1000 nm, while some sensors use near-infrared illumination based on the enhanced sensitivity between 700 and 1000 nm. In high-capacity markets, such as consumer electronics, it may be more cost-effective to select laser diodes of standard wavelengths for the system.
Output power considerations
The choice of optical power usually needs to consider system operating conditions, laser safety and life, and cost factors.
Optical design
The purpose of optical design is to provide the beam shape and size required by the system within the working distance range. By selecting an appropriate laser light source, redundant optical components can be simplified, and cost reductions are possible without sacrificing performance.
Thermal Management
The working environment temperature will affect the output stability and lifetime of the laser, so thermal management is an important consideration. When designing and using laser modules, the system needs sufficient heat dissipation. Choosing a laser diode with low-temperature sensitivity and wide operating temperature is particularly important for system performance.
Mechanical Principles
The laser module combines multiple components, including a laser diode, one or more optical components, and electronic components (to control the output of the laser diode). These components are encapsulated in the module housing to provide protection while maintaining precise positioning with each other under normal operating, storage, and transportation conditions. Under the trend of module miniaturization, it is essential to realize the performance of modules by cooperating with high-quality manufacturers with professional experience regarding the customization requirements of OEM and end customers.
Drive Circuit
The design of most laser modules includes a drive circuit to control and stabilize the output power conditions and the service life of the parts within the working range.
Partner Selection
The success of the laser module involves the development, design, manufacturing, and testing processes. OEM customers are required to work closely with laser module manufacturers in terms of design and manufacturing process. The ability of the laser manufacturer to accurately understand customer requirements, and provide input based on professional experience and development capabilities, coupled with fast-paced efficiency, will help OEM customers successfully manufacture ideal laser modules.
Laser Modules Shine in AIOT Applications
With the rapid development of artificial intelligence and the Internet of Things (AIOT), the application of laser modules has ushered in a broader development space. Traditional laser modules typically utilize visible light, mainly used in the field of indication and sensors, such as laser pointers and handheld laser rangefinders, which are mainly convenient for human eyes to see. As a substitute for visible light, infrared laser modules have the characteristics of monochromaticity and narrow bandwidth, which can simplify image processing, match specific receiving spectrum, and improve the system’s overall efficiency. Therefore, it is advantageous in many sensors of AIOT. In addition, with the wide application of AIOT, invisible infrared laser modules are also an ideal choice to reduce and avoid light pollution.
In robot navigation and obstacle avoidance, 808nm, 850nm and 940nm are commonly used wavelengths, which are invisible to the human eye. They have been widely used in sweepers, 3D scanning, machine vision, etc. Traditional laser modules are mostly edge-emitting lasers. Due to the higher cost, lower reliability, and larger size of edge-emitting lasers, they cannot sufficiently meet the growing market demand for AIOT. VCSEL vertical cavity surface emitting lasers have the advantages of low costs, high reliability, surface packaging, etc. VCSELs have rapidly become the best choice for replacing edge-emitting lasers in AIOT applications.
According to the requirements of laser modules required by AIOT sensors, we have designed and mass-produced a variety of 808nm, 850nm, and 940nm VCSEL chips. We provide customers with one-stop, diversified VCSEL laser module products and technical support. Our VCSEL laser modules have been widely used in 3D scanning, LiDAR, machine vision, and laser medical fields worldwide, and have been widely recognized by customers.
Below we outline some laser module examples based on different applications:
Dot laser module for triangular laser scanning LIDAR
Triangular laser scanning LIDAR requires a collimated point laser module, with ≈ 1 mW power and wavelength typically 808 nm / 850 nm
Laser modules for safety light curtains
This is a long-distance light curtain with small divergence angle (0.8 mrad), 940 nm wavelength, 300-500m transmission range, and can be used as safety light curtain light source for railway station and subway station platforms, for example.
This line module can be used as a short-range and large-scale safety light curtain light source. With a wavelength of 940nm and a divergence angle of 120 deg., and it covers a range of 0.3-5 meters. Various power levels available.
Modules for laser obstacle avoidance LIDAR
This laser line module is widely used in laser obstacle avoidance LIDAR. The range is 0.3-2 meters, and available wavelengths are 808 nm, 850 nm, and 940 nm. It has the advantages of thin and uniform lines and high power density. The angle options are 45°, 60°, 90°, 110°, 120°, 130° and 160° – widely used in sweeping robots, screen door monitoring and other scenarios.
Laser modules for scanning
This laser line module is widely used in the field of 3D scanning, including consumer and machine vision applications. Available wavelengths are 808 nm, 850 nm, and 940 nm, with thin & long lines, no speckle, and high-quality 3D scanning accuracy.
Laser modules for machine vision
This laser line module is specially designed for machine vision. Available wavelengths are 660 nm, 808 nm, and 850 nm – specially used to detect small defects such as small scratches. It adopts a good heat dissipation design and has the advantages of all-weather work and high reliability.
Collimated laser modules for dToF
This collimating point module has high peak power, nanosecond response time, power options of 10 W, 20 W, 50 W, and 100 W, and available wavelengths are 850 nm, and 940 nm – replacing traditional edge-emitting PLDs.
How Can We Help?
With over 25 years experience providing VCSEL lasers to researchers and OEM integrators working in various markets and applications, and 1000s of units fielded, we have the experience to ensure you get the right product for the application. Working with RPMC ensures you are getting trusted advice from our knowledgeable and technical staff on a wide range of laser products. RPMC and our manufacturers are willing and able to provide custom solutions for your unique application.
If you have any questions, or if you would like some assistance please Contact Us here. Furthermore, you can email us at info@rpmcdev.maxdroplet4.maxburst.dev to talk to a knowledgeable Product Manager.
Alternatively, use the filters on this page to assist in narrowing down the selection of VCSEL lasers for sale. Finally, head to our Knowledge Center with our Lasers 101 page and Blogs, Whitepapers, and FAQ pages for further, in-depth reading.
Finally, check out our Limited Supply – In Stock – Buy Now page: This page contains an ever-changing assortment of various types of new lasers at marked-down/discount prices.
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The most common light source on the market is LED light sources. VCSELs can be arranged in two-dimensional VCSEL arrays so that a single chip can contain hundreds or thousands of individual light sources. VCSEL arrays allow an increase maximum output power and long-term reliability in a small footprint. LED is usually used in the early stage of 3D induction technology. However, due to the lack of resonator, LED laser beams are more dispersed than VCSEL, and the coupling efficiency is relatively low. Moreover, as VCSEL has higher accuracy, smaller size, lower power consumption, and higher reliability, more and more 3D cameras are using these devices.
