PbS vs PbSe: Choosing the Right Lead-Salt Infrared Detector

Lead sulfide (PbS) and lead selenide (PbSe) are the two lead-salt infrared detector families offered by Opto Diode, and although they share a photoconductive heritage, they cover different parts of the infrared spectrum and suit different sensing problems. PbS is tuned for the short-wave infrared (SWIR), while PbSe reaches further into the mid-wave infrared (MWIR). Picking the right family early in your design saves time, cost, and re-spins—so this guide walks an engineer through the practical differences.

Need a specific two-stage cooled PbSe part? See the BXT2 series detectors.

Both families are offered by Opto Diode, located in Camarillo, CA (a division of ITW), in uncooled packaged, one-stage cooled, and two-stage cooled configurations.

PbS vs PbSe at a Glance

Opto Diode offers both families in a range of active-area sizes—PbS in active-area sizes up to 36 mm² and PbSe up to 9 mm²—so you can match the detector to your optical system as well as to your wavelength band.

Choose PbS if…

• Your signal of interest falls within the 1 µm to 3.5 µm SWIR band.
• You need low noise and high detectivity for low-light or low-level infrared signals.
• Long-term stability matters for your instrument—PbS detectors are noted for excellent long-term stability.
• Your application is gas sensing and spectroscopy, flame and fire detection, or remote temperature sensing in the SWIR.
• You want flexibility between uncooled packaged detectors (AP series) and cooled options (AT series, one- and two-stage) depending on your sensitivity and operating-temperature requirements.
• You need a larger active area than the PbSe line provides—PbS is available up to 36 mm².

Explore Opto Diode’s PbS detectors.

Choose PbSe if…

• Your target wavelength extends into the MWIR, out to 5.5 µm—beyond the reach of PbS.
• You need a wide spectral response combined with high sensitivity and **high detectivity (D*)** with low noise.
• You want cooled options, including one-stage and two-stage cooled configurations, to improve performance.
• Your application is gas analysis and spectroscopy, flame and combustion monitoring, aerospace and defense, or thermal imaging.
• Your spectroscopy targets MWIR absorption features that simply fall outside the SWIR window.

Explore Opto Diode’s PbSe detectors.

Representative Models

PbS (Lead Sulfide)

• Uncooled, packaged: AP-15G, AP-25G, AP-20505, AP-58E, AP-68
• One-stage cooled: AT1-27TE, AT1-37T
• Two-stage cooled: AT2-28TE, AT2-37T, AT2S-38T

PbSe (Lead Selenide)

• Uncooled: BXP-15E, BXP-25M, BXP-35E, BXP-35F
• One-stage cooled: BXT1-28TE, BXT1-37T
• Two-stage cooled: BXT2-17T, BXT2-27, BXT2-37T, BXT2S-28T, BXT2S-38T

It Often Comes Down to Wavelength

For most designs, the deciding factor is the target wavelength. If your measurement lives in the short-wave infrared—roughly the 1–3.5 µm region—PbS is the natural fit, offering low noise and proven long-term stability. If your spectral feature sits further out in the mid-wave infrared, up to 5.5 µm, PbSe is the family to reach for, since PbS simply does not extend that far.

In gas-sensing applications this distinction is especially important: species and absorption bands that fall in the longer-wave MWIR favor PbSe, while those that fall in the shorter-wave SWIR favor PbS. The same logic applies to flame and combustion work, where the relevant emission band should drive the choice. When a target sits near the boundary of both ranges, factor in the cooling option, active-area size, and required sensitivity to make the final call.

Talk to Opto Diode

Still deciding between PbS and PbSe, or need a configuration that isn’t on the shelf? Opto Diode offers both lead-salt families and supports a range of packaging and active-area options. Contact Opto Diode for a quote and our engineering team will help match a detector to your wavelength band, cooling needs, and application.

Frequently Asked Questions

Which detector detects longer wavelengths, PbS or PbSe?

PbSe. Opto Diode’s PbSe detectors respond from 1 µm to 5.5 µm (MWIR), while PbS detectors cover 1 µm to 3.5 µm (SWIR). PbSe reaches further into the infrared.

Which family is better for MWIR gas analysis?

PbSe is the MWIR family and is applied to gas analysis and spectroscopy, making it the right starting point when your target absorption feature falls in the mid-wave infrared. For SWIR gas sensing, PbS is the appropriate choice.

Do these detectors offer cooling options?

Yes. Both families are available in uncooled packaged versions as well as cooled configurations, including one-stage and two-stage cooled options, so you can trade off complexity against performance.

Can Opto Diode customize a PbS or PbSe detector?

Opto Diode offers both families in a range of active-area sizes and cooling configurations. Contact the team via the contact page to discuss requirements that go beyond the standard catalog.

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