VCSEL Wavelength Customization for Medical Wearables

Medical wearables have moved from gadgets to everyday health companions. From smartwatches to continuous monitoring patches, they all rely on light to “read” the body. At the core of many of these modules is the VCSEL (Vertical-Cavity Surface-Emitting Laser) – and more specifically, the VCSEL wavelength selected for the job.

As a VCSEL manufacturer, we design wavelengths, power levels and packages so that each device can measure the right biomarker with the right light.

1. What VCSEL Wavelength Customization Means

1.1 Basics of VCSEL Technology

A VCSEL is a compact semiconductor laser that emits light vertically from the chip surface through a short resonant cavity formed by distributed Bragg reflectors (DBRs). This architecture delivers:

  • A near-circular, low-divergence beam

  • Narrow spectral linewidth and stable VCSEL wavelength

  • The ability to test and bin devices at the wafer level

  • Easy integration into arrays, chips, packages and modules

For Ace Photonics, the focus is on single-mode VCSELs in the 750–900 nm band, especially around 760, 795 and 895 nm, which are workhorse wavelengths for sensing and quantum applications.

1.2 Why VCSEL Wavelength Matters in Biology

Different wavelengths penetrate tissue differently and interact with specific chromophores such as hemoglobin, water and glucose. By tailoring the VCSEL wavelength, we can:

  • Improve signal contrast for a given biomarker

  • Reduce cross-talk from other absorbers

  • Keep optical power within eye-safe and skin-safe limits

In medical wearables, this directly translates into more reliable heart-rate curves, cleaner SpO₂ signals and more robust algorithms for advanced biomarkers.

VCSEL wavelength options optimized for medical wearable sensors

2. Why VCSEL Wavelength Customization Is Critical for Wearables

2.1 Higher Precision in Optical Sensors

Custom VCSEL wavelengths allow the optical stack to “lock in” on the desired physiological signal:

  • Heart-rate and HRV – Wavelengths in the near-IR band are tuned to the absorption spectrum of hemoglobin, so the sensor tracks subtle pulsatile changes even during motion.

  • SpO₂ (blood oxygen) – Using a pair or set of well-chosen wavelengths, the system can distinguish oxygenated and deoxygenated hemoglobin and compute oxygen saturation with high accuracy.

Rather than using a generic laser or LED, we set the VCSEL wavelength and linewidth to match the optical model of the wearable system – photodiode response, filter design, skin path length and algorithm requirements.

2.2 Comfort and Safety for Long-Term Use

A wearable only works if users forget they are wearing it. VCSEL wavelength selection influences:

  • Perceived brightness and skin comfort – Operating in the near-IR range keeps the light largely invisible and comfortable for continuous use.

  • Thermal load and battery life – Efficient VCSELs at optimized wavelengths reach the required signal-to-noise ratio (SNR) at lower drive currents, reducing heating and power consumption.

By aligning wavelength, optical power and duty cycle, we help OEMs meet regulatory and comfort constraints while preserving measurement quality.

3. Key Medical Wearable Applications of VCSEL Wavelength

3.1 Heart-Rate and Activity Monitoring

In wristbands and smartwatches, a VCSEL-based PPG (photoplethysmography) module measures blood volume changes under the skin. When the VCSEL wavelength is tuned to hemoglobin absorption peaks and detector response, the module can:

  • Maintain clean pulse waveforms during running or cycling

  • Improve heart-rate variability (HRV) estimation

  • Reduce susceptibility to ambient light interference

3.2 Blood Oxygen (SpO₂) Monitoring

SpO₂ modules work by comparing light absorption at different wavelengths. Carefully selected VCSEL wavelengths:

  • Increase discrimination between Hb and HbO₂

  • Allow shorter integration times and faster updates

  • Support miniaturized optical paths suitable for finger, wrist or ear-canal wearables

This is crucial for patients with respiratory conditions and for athletes training at altitude.

3.3 Non-Invasive Glucose and Metabolic Sensing

Non-invasive glucose monitoring is an emerging use case where VCSEL wavelength tuning is essential. By targeting absorption features associated with glucose and related analytes, multi-wavelength VCSEL architectures can:

  • Provide trend-level glucose information without lancets

  • Combine with other biomarkers (heart-rate, SpO₂, temperature) for richer metabolic profiles

Although this field is still maturing, flexible VCSEL wavelength platforms make it possible to iterate quickly as algorithms and clinical evidence evolve.

3.4 795 nm / 895 nm in Wearable Devices

Our 795 nm-1 mW and 895 nm-1 mW single-mode VCSELs have become popular choices in wearables because they couple strongly to hemoglobin while remaining eye-safe and detector-friendly.

  • These VCSEL wavelengths are well suited for heart-rate and SpO₂ channels.

  • SMD (surface-mount) packages keep the optical path short and enable low-profile modules that drop straight onto standard SMT lines.

4. How VCSEL Wavelength Customization Improves Accuracy

4.1 Minimizing Signal Interference

Wearables must operate in the real world, not in a dark lab. VCSEL wavelength choices and optical filtering work together to:

  • Avoid strong ambient light bands (e.g., some LED lighting spectra)

  • Reduce overlap with other emitters in multi-sensor devices

  • Maintain SNR under motion and varying skin conditions

This lets the signal-processing chain focus on clean physiological data instead of fighting background noise.

4.2 Adapting to Different Skin Types

Melanin and other skin components absorb light differently across the spectrum. By tuning VCSEL wavelengths and power, plus adjusting algorithms, systems can:

  • Normalize signal quality across a wide range of skin tones

  • Reduce calibration bias between users

  • Support global deployment with consistent performance

A flexible wavelength platform lets OEMs refine their product after field testing, without redesigning the entire optical engine.

5. Engineering and Business Challenges

5.1 Technical Complexity

Producing VCSELs at a specific wavelength with tight tolerance demands:

  • Carefully engineered epitaxial stacks for the target VCSEL wavelength

  • Quantum-well design tuned to gain at that wavelength

  • Precision in DBR layer thickness and oxidation apertures

Ace Photonics has deep experience in GaAs-based VCSEL R&D and manufacturing, including ICP etching, wet oxidation and BCB processes, enabling stable volume production of customized wavelengths.

5.2 Cost Considerations

Every additional bin, spec or package variant has cost implications. Custom VCSEL wavelengths can:

  • Require specialized test setups and calibration

  • Increase sorting complexity at wafer level

  • Add NRE (non-recurring engineering) for unique designs

Our goal is to balance customization with manufacturability, so that medical wearable projects can scale from prototype to mass production without a cost shock.

6. How We Overcome Customization Challenges

6.1 Advances in VCSEL Manufacturing

Modern VCSEL processes allow us to maintain tight control over the emission wavelength while improving yield:

  • Advanced lithography and etching for uniform device geometry

  • Process windows designed for high temperature stability and long-term reliability

  • Wafer-level testing to bin VCSEL wavelength and output power before dicing

6.2 Cost-Effective Customization

To keep customized VCSEL wavelengths accessible for wearable OEMs, we:

  • Re-use proven platform epitaxy where possible (e.g., 760/795/895 nm families)

  • Offer multiple power levels and packages (bare die, TO-can, SMD, non-magnetic) built on common footprints

  • Optimize test and burn-in flows to support high-volume production without compromising reliability

7. Ace Photonics’ Role in Medical Wearable Innovation

7.1 Specialization in VCSEL Wavelength Platforms

Ace Photonics is a dedicated VCSEL manufacturer, with core expertise in single-mode VCSELs and high-performance packages in the 750–1550 nm range.

For medical wearables, we focus on:

  • 760, 795, 890/895 nm VCSEL wavelength families

  • Narrow-linewidth devices for precise sensing

  • High-temperature operation and non-magnetic options where required

7.2 Customization Options for OEMs

We collaborate with device makers from early concept through regulatory-ready designs. Our customization options include:

  • Center VCSEL wavelength and tuning range

  • Optical power (e.g., 0.1 mW, 1 mW, 1.8 mW) and drive conditions

  • Package choice: bare chip, TO-can, SMD, non-magnetic assemblies

  • Array geometries where multi-beam architectures are required

7.3 SMD Packaging for Ultra-Compact Wearables

For wristbands, rings and patches, SMD VCSELs are often the preferred solution:

  • Low Z-height for thin industrial designs

  • Compatibility with standard SMT reflow and pick-and-place lines

  • Tight integration with drivers, photodiodes and optics on a single PCB

This lets customers move quickly from evaluation boards to production-ready modules.

8. Future Directions in VCSEL Wavelength for Wearables

8.1 More Personalized Sensing

As algorithms and cloud platforms mature, wearables will increasingly adapt to the individual. Tunable VCSEL wavelength combinations, per-user calibration and AI-driven analytics will enable:

  • Personalized thresholds and alerts

  • Long-term trend tracking across multiple biomarkers

  • Adaptive optical power and wavelength strategies tuned to each user’s physiology

8.2 Integration with AI and Multi-Sensor Fusion

Pairing VCSEL-based optical data with inertial, temperature and environmental sensors – and analyzing everything with AI – will unlock deeper insights:

  • Predictive models of cardiovascular or metabolic risk

  • Context-aware health coaching and anomaly detection

  • New composite metrics that go beyond single vital signs

A robust VCSEL wavelength portfolio ensures that the optical layer keeps pace with this software-driven evolution.

9. Conclusion

VCSEL wavelength customization is one of the key levers behind the next generation of medical wearables. By choosing and engineering the right wavelengths, we can:

  • Raise the accuracy of heart-rate, SpO₂ and emerging non-invasive biomarkers

  • Improve comfort, safety and battery life for long-term wear

  • Support inclusive performance across diverse users and use conditions

At Ace Photonics, we combine wavelength-engineered VCSELs, flexible packaging and OEM collaboration to help customers turn ambitious wearable roadmaps into manufacturable products. As demand for smarter health devices accelerates, a carefully designed VCSEL wavelength strategy will be a core differentiator for high-performance medical wearables.

View full VCSEL wavelength table here