Bandpass filters are important optical components in shaping the spectrum of light. Many optical devices rely on bandpass filters to provide more signal and less background, essentially isolating frequencies within a particular band which are desirable for one reason or another. This ability to selectively transmit signals within a certain band and block signals of lower and higher frequencies is integral to a wide range of applications.

Applications of Bandpass Filters

Bandpass filters are commonly used in Raman spectrometers and any spectroscopy instrument that has on-axis signal from unwanted wavelengths. Laser line bandpass filters are optimized to reduce spectral noise from the laser source, with a passband transmission of up to 90% for the desired wavelength. With a steep transition between passband and deep blocking, portable Raman spectrometers equipped with bandpass filters have become popular in art conservation, healthcare and many other areas but such devices require very high optical stability.

A custom bandpass filter in optical devices can give an excellent optical performance, maximizing the desired signal transmission, blocking any unwanted background, and helping with device stability. The custom bandpass filter can be designed to be part of an integrated optic scheme to be both compact and lightweight in terms of size and improve stability. 

For telecom, custom bandpass filters ensure minimal cross-talk in multiplexed information transfer. This can help improve efficiency, and high-quality custom bandpass filters are a good way of providing excellent transmission in the pass region to avoid unwanted signal losses. Essentially, bandpass filters are central to ensuring that multiple signal bands reach multiple different end users.

Mid-wave IR Bandpass Filters

A custom bandpass filter series can be created for; specifically, the central wavelengths required and to cope with any unwanted signal in the fiber. The ability to modulate a spectrum with a bandpass filter has made them a vital component in optical-based telecommunication approaches and satellite communications.

Benefits of Custom Bandpass Filters

If you are an optical designer considering whether a custom bandpass filter is the right solution for you, consider some of the following key properties. 

The first is the central wavelength, which determines the middle of the transmitted spectrum. The bandwidth of the transmitted region can also be controlled, so bandpass filters can let as little as 1 nm through or be much more broadband depending on requirements.

Other considerations are the uniformity of the blocking – many applications need an even step-function in the transmitted region with a high contrast of > 95 % between the blocked and transmitted wavelengths. The wavelength region of operation is also an important consideration as this will affect the materials used in the bandpass filter.

A custom bandpass filter can be designed to have precisely the desired optical properties. Optical designers often recommend custom bandpass filters as they are an ideal solution for either bespoke instrument design or where off-the-shelf solutions do not have the desired performance.

Custom bandpass filters do not have to be expensive or require long lead times. Iridian are leading specialists in custom optical solutions and have been supporting customers worldwide in since 1998.

With our broad design experience, we can support you with the development and manufacturing of optical systems using our custom bandpass filters. Various proprietary manufacturing technologies are at hand, and our dedicated team of experts can help you find the ideal, cost-effective solution for your system. Often, custom bandpass filters fulfill customer needs.

Contact Iridian today to find out how their custom bandpass filters can benefit your application and improve performance.