1550nm/50nm Bandwidth Optical Filter  Overview

The 1550nm/50nm Bandwidth Optical Filter employs a hard dielectric multilayer film design, with a center wavelength of 1550 nm, a FWHM of 50 nm, and a passband of approximately 1525–1575 nm. Peak transmittance is typically ≥95% @1550 nm, with a cutoff depth (OD4) greater than 400–1800 nm outside the passband. The 50 nm bandwidth strikes a balance between transmittance and ambient light suppression, covering the temperature-dependent wavelength range of the 1550 nm light source while effectively suppressing out-of-band background. It is commonly used in automotive and drone LiDAR, shortwave infrared and machine vision, and fiber optic communication applications.

As a manufacturer of SWIR filters, we select different substrates based on project requirements, such as fused silica, B270, and other optical glasses, and customize and design the film system according to the customer’s laser wavelength and incident angle.

1550nm/50nm Bandwidth Optical Filter Product Features

It has key features below:

• Center wavelength 1550nm, bandwidth 50nm, perfectly matched to 1550nm laser wavelength.
• Nearly 100% transmittance within the passband; our manufacturing transmittance standard is greater than or equal to 95%, maximizing the throughput of 1550nm signal light and minimizing optical energy loss.
• Cutoff depth OD4-OD6 in the 400-1800nm ​​range outside the passband, suppressing ultraviolet to visible light and long-wave infrared regions, possessing extremely strong out-of-band stray light thresholding capability.
• We use IAD hard coating, therefore the filter has extremely high scratch resistance, high temperature and high humidity resistance, and good environmental stability.

1550nm/50nm Bandwidth Optical Filter Manufacturer Spectrum

1550/50nm Infrared Interference Filter Specification

• CWL：1550+/-5nm
• FWHM: 50+/-5nm
• Tp>=95%
• Blocking: 200-1100nm@OD4-OD6

Coligh Customize Capability Of Hard-Coated IAD SWIR Filter

As a professional optical component manufacturer, Coligh offers customized sizes and shapes based on customer mechanical structures. We also maintain a large inventory, allowing us to fine-tune the center wavelength and bandwidth according to laser characteristics. Furthermore, we can provide anti-laser damage coatings for high-power continuous or pulsed 1550nm laser systems. Our own coating equipment and cold processing workshop ensure short lead times, high cost-effectiveness, and support for both small-batch prototyping in research and stable large-scale industrial delivery.

SWIR 1550nm Narrowband Filter Applications

SWIR Imaging and Industrial Inspection

SWIR imaging can penetrate silicon, some plastics, smoke, and coatings, and can identify moisture, internal structures, and hidden defects. However, SWIR cameras (such as InGaAs detectors) receive not only the target signal but also ambient light, sunlight, thermal radiation, and out-of-band infrared stray light, leading to decreased contrast and false positives. Using a 1550 nm / FWHM 50 nm SWIR bandpass filter allows only target light near 1550 nm to pass through, suppressing other bands and improving image signal-to-noise ratio and detection stability.

Laser Ranging and LiDAR

When 550 nm laser ranging and LiDAR systems operate outdoors, the receiver receives sunlight, ambient infrared light, and long-wave background, reducing ranging accuracy and detection range. 1550 nm offers eye safety advantages in some applications, allowing for relatively higher emission power, but a high signal-to-noise ratio is still required at the receiver. Narrowband filters allow only laser echoes around 1550 nm to pass through, suppressing other wavelengths and improving the signal-to-noise ratio.

Optical Communication and Modules

1550 nm is a commonly used wavelength band in optical communication and fiber optic sensing. Test systems, EDFA testing, optical power monitoring, and coarse wavelength division multiplexing (WDM) systems require band selection and stray light suppression. FWHM 50 nm is suitable for applications with a wide spectral range, suppressing out-of-band background while maintaining transmittance. For narrower bandwidths, FWHM 10–30 nm versions can be customized.

Gas Sensing and Moisture/Humidity Detection

Some gases and substances have absorption lines or characteristic responses around 1550 nm, which can be used for TDLAS, NDIR, or spectral sensing. However, broadband light sources and ambient light can introduce interference, reducing selectivity and detection limits. A 1550 nm / FWHM 50 nm bandpass filter can isolate the target wavelength band and suppress interference from other wavelengths.