Jun 11, 2026Technical Insights

795nm and 894.6nm VCSEL Sources for OPM Magnetometer Projects | Rb and Cs D1-Line Options

795nm and 894.6nm single-mode VCSEL sources for Rb and Cs OPM magnetometers, vapor-cell magnetic sensing, OSRAM / Vixar alternative review and non-magnetic package discussion.

894.6nm single-mode VCSEL bare die for Cs OPM magnetometer

795nm and 894.6nm VCSEL Sources for OPM Magnetometer Projects

Optically pumped magnetometers, also known as OPM magnetometers or atomic magnetometers, use the interaction between laser light and alkali-metal atoms to measure weak magnetic-field signals. In a typical vapor-cell OPM system, the optical source must be matched to the atomic transition line, while the package, beam profile, polarization optics, thermal control and detector response must be reviewed together.

For rubidium- and cesium-based OPM magnetometer projects, 795nm and 894.6nm single-mode VCSELs are important optical source candidates. 795nm VCSELs are commonly used for rubidium D1-line optical pumping, while 894.6nm VCSELs are used for cesium D1-line optical pumping.

1ONELASER provides standard single-mode VCSEL bare die products for both OPM directions:

795nm single-mode VCSEL bare die for Rb OPM magnetometer projects

894.6nm single-mode VCSEL bare die for Cs OPM magnetometer projects

Standard products are supplied as bare die by default. For OPM magnetometer projects requiring packaged optical sources, TO-46 non-magnetic package support can be discussed. Collimation, beam shaping, divergence control and customer-specific spot-size requirements can also be reviewed according to the final vapor-cell optical layout.

Why VCSEL Source Selection Matters in OPM Magnetometer Systems

OPM magnetometer performance is not determined by wavelength alone. The final magnetic-field signal depends on the interaction between the VCSEL, vapor cell, optical pumping path, polarization optics, thermal control, detector response and magnetic shielding structure.

In practical Rb OPM and Cs OPM systems, the VCSEL source should be reviewed together with:

Alkali-metal atom type: Rb or Cs

D-line wavelength matching

Spectral linewidth

Single-mode suppression ratio, or SMSR

Polarization extinction ratio, or PER

Optical output power

Beam divergence and collimation

Vapor-cell temperature condition

Magnetic shielding and low-magnetic package requirements

Detector response and final magnetic-field signal behavior

This is why a 795nm or 894.6nm VCSEL should be validated under the customer's actual optical, thermal, electrical and magnetic-field sensing conditions. A higher output-power VCSEL can be valuable, but the final result still depends on the complete OPM optical path and vapor-cell system design.

795nm VCSEL for Rb OPM Magnetometers

The 795nm single-mode VCSEL bare die is designed for rubidium D1-line optical pumping in Rb-based optically pumped magnetometers, vapor-cell magnetic sensing modules and compact quantum sensing optical source systems.

Typical application directions include:

Rubidium-based OPM magnetometer

Rb vapor-cell magnetic sensing

Rubidium D1-line optical pumping

Quantum magnetic-field sensing optical source

Laboratory OPM optical source testing

Compact vapor-cell sensor module development

The 1ONELASER 795nm OPM VCSEL provides 0.7mW typical optical output power at IF = 2mA, with 35dB minimum SMSR, 20dB minimum PER and 30MHz maximum spectral linewidth.

For engineering teams that previously evaluated OSRAM / Vixar 795nm single-mode VCSEL references, output power is an important system-level difference. Compared with legacy OSRAM / Vixar 0.3mW-class or lower-power reference designs, a 0.7mW 795nm VCSEL can provide significantly higher optical power margin for rubidium vapor-cell coupling, optical pumping efficiency, collimation, beam shaping and detector signal optimization.

This higher optical power margin can be especially valuable in OPM magnetometer systems, where optical losses may come from package windows, collimation optics, waveplates, vapor-cell windows, alignment tolerance and compact module geometry. A higher-power 795nm VCSEL source gives the system designer more flexibility to balance optical pumping strength, beam size, working distance and final magnetic-field signal response.

This does not mean the device is a direct drop-in replacement for every OSRAM / Vixar design. Final suitability should still be validated under the customer's actual optical, thermal, electrical, magnetic shielding and vapor-cell sensing conditions.

Product page: 795nm Single-Mode VCSEL Bare Die for Rb OPM Magnetometer

894.6nm VCSEL for Cs OPM Magnetometers

The 894.6nm single-mode VCSEL bare die is designed for cesium D1-line optical pumping in Cs-based optically pumped magnetometers, cesium vapor-cell magnetic sensing systems and compact quantum sensing optical source modules.

Typical application directions include:

Cesium-based OPM magnetometer

Cs vapor-cell magnetic sensing

Cesium D1-line optical pumping

Compact Cs vapor-cell magnetometer module development

Quantum sensing optical source development

Laboratory OPM optical source testing

The 1ONELASER 894.6nm OPM VCSEL provides 1.0mW typical optical output power at IF = 2mA, with 30dB minimum SMSR, 20dB minimum PER and 50MHz maximum spectral linewidth.

For engineering teams reviewing OSRAM OLI0608V.A1-895-A-style 894.6nm single-mode VCSEL references, the key comparison should include more than center wavelength. Output power, linewidth, SMSR, PER, field of view, thermal tuning behavior, drive condition, package format and final Cs vapor-cell signal response should all be reviewed.

Compared with legacy OSRAM 0.3mW-class 894.6nm references, a 1.0mW 894.6nm VCSEL option provides more optical power margin for Cs vapor-cell coupling, optical pumping, collimation, beam shaping and system-level magnetic-field signal optimization.

This higher output-power margin is useful because OPM magnetometer systems often include optical loss from package windows, collimation optics, polarization optics, vapor-cell windows and alignment tolerance. A 1.0mW-class 894.6nm VCSEL gives the optical design more usable margin before the light reaches the cesium vapor cell.

Final validation is still required under the customer's actual OPM system conditions.

Product page: 894.6nm Single-Mode VCSEL Bare Die for Cs OPM Magnetometer

Rb and Cs OPM VCSEL Selection Summary

Application Direction	Alkali Metal	VCSEL Wavelength	Typical Optical Power	Product Form	Package Discussion
Rb OPM Magnetometer	Rubidium	795nm	0.7mW typ.	Bare die by default	TO-46 non-magnetic package discussion
Cs OPM Magnetometer	Cesium	894.6nm	1.0mW typ.	Bare die by default	TO-46 non-magnetic package discussion

Both products are intended for vapor-cell magnetic sensing and OPM magnetometer optical source applications. For projects requiring a packaged source, low-magnetic material selection, TO-46 non-magnetic packaging, beam collimation and custom optical spot requirements can be reviewed during the engineering discussion stage.

Why Higher Optical Power Margin Helps OPM System Design

In an OPM magnetometer, the useful optical power reaching the vapor cell may be lower than the bare VCSEL output power. Losses can be introduced by the package window, collimation lens, waveplate, polarizer, vapor-cell window, beam alignment and compact mechanical structure.

For this reason, higher VCSEL output power can provide important design margin. It allows the engineering team to review a wider range of optical layouts, beam diameters, working distances and polarization configurations before reaching the final signal requirement.

For the 795nm Rb OPM direction, moving from a legacy 0.3mW-class or lower-power OSRAM / Vixar reference to a 0.7mW-class VCSEL can give more margin for optical pumping strength and detector signal optimization.

For the 894.6nm Cs OPM direction, moving from a legacy 0.3mW-class OSRAM reference to a 1.0mW-class VCSEL can give more margin for Cs vapor-cell coupling, collimated beam delivery and magnetic-field signal response.

The advantage is not only a larger datasheet number. The engineering value is the additional optical power available after real system losses.

Why TO-46 Non-Magnetic Packaging Matters

In OPM magnetometer systems, package material selection can affect the local magnetic environment around the vapor cell. For this reason, the optical source package should be reviewed together with the magnetic shielding structure, vapor-cell position, heater design, detector layout and system-level noise requirements.

For selected OPM projects, TO-46 non-magnetic package support can be discussed. This may include review of package structure, material selection, bonding layout, thermal path, window configuration, collimation and beam alignment.

Non-standard packaging should be treated as a project-level engineering discussion, not only a simple product ordering item.

Collimation and Custom Beam Spot Discussion

VCSEL bare die products provide flexibility for compact optical source development, but real OPM magnetometer systems often require a defined beam path. Depending on the vapor-cell geometry and optical layout, the customer may need collimation, divergence control, beam shaping or a specific spot size at the vapor cell.

For selected OPM projects, collimation and custom optical spot requirements can be reviewed together with:

VCSEL field of view

Working distance

Vapor-cell window size

Beam diameter requirement

Optical alignment tolerance

Package window design

Lens or micro-optics selection

Detector signal requirement

This is especially important when converting a bare die VCSEL into a packaged optical source or a compact vapor-cell module.

Evaluation Kits and Engineering Review

For selected standard bare die products, 5-piece evaluation kits can be arranged subject to product availability and project review. Evaluation kits help engineering teams review wavelength matching, optical power, drive condition, beam behavior and early optical path compatibility before moving into deeper packaging or module-level development.

For OPM magnetometer projects, 1ONELASER can support discussion around:

795nm and 894.6nm single-mode VCSEL bare die

Rb and Cs D1-line optical pumping

TO-46 non-magnetic package development

Collimated optical source requirements

Beam shaping and customized spot size

TEC / temperature-control discussion

Documentation and datasheet review