IOT-G-1550A

• Designed for 1550 nm laser systems.
• Provides non-reciprocal optical isolation using the Faraday effect.
• Helps protect lasers from back-reflected light and optical feedback.
• Designed for free-space optical systems rather than fiber-only systems.
• Suitable for near-infrared (NIR) photonics.
• High-performance polarization-based isolation architecture.
• Suitable for integration into precision laser and optical measurement systems.
• Particularly useful for systems where unwanted reflections can cause laser instability, noise, or frequency fluctuations.
• Compatible with applications in telecommunications, spectroscopy, interferometry, sensing, and photonics research.
• 1550 nm operation makes it particularly relevant to systems using common 1550 nm laser sources and optical components. Thorlabs also offers 1550 nm fiber components and collimators optimized around this wavelength.

The Thorlabs IOT-G-1550A is a free-space optical isolator designed for 1550 nm laser systems. It uses the Faraday effect to provide non-reciprocal polarization rotation, allowing light to propagate efficiently in the forward direction while suppressing light traveling back toward the laser source.

Optical isolation is particularly important in precision laser systems because reflections from downstream optics, fiber interfaces, samples, or other optical components can return toward the laser. Such feedback can introduce unwanted intensity noise, frequency instability, mode hopping, or changes in laser output characteristics.

Unlike a conventional waveplate, the Faraday rotator inside an optical isolator provides non-reciprocal rotation. Consequently, light traveling backward does not simply retrace the polarization transformation of the forward beam. When combined with polarizing elements, this allows the isolator to strongly attenuate reflected light.

The 1550 nm operating wavelength makes the IOT-G-1550A suitable for NIR systems and applications where 1550 nm is commonly used. Thorlabs' 1550 nm optical ecosystem includes single-mode fiber, fiber patch cables, and fiber collimators optimized for this wavelength, facilitating integration into larger free-space/fiber hybrid optical systems.

Product Type: Free-Space Optical Isolator
Part Number: IOT-G-1550A
Design Wavelength: 1550 nm
Operating Region: Near Infrared (NIR)
Isolation Principle: Faraday Effect
Optical Configuration: Free Space
Function: Non-Reciprocal Optical Isolation
Primary Function: Suppression of Back Reflections
Polarization: Polarization Dependent
Application Type: Laser Protection / Optical Feedback Suppression

Important Note

For the IOT-G-1550A, I recommend keeping the product page specification table conservative unless the exact value is confirmed from the current Thorlabs datasheet. The Thorlabs item page itself does not expose its specification table through the current web page retrieval, and I don't want to introduce potentially incorrect values for parameters such as isolation, transmission, maximum beam diameter, or maximum optical power.

For comparison, Thorlabs' current 1550 nm isolator family includes configurations ranging from very-low-power units to high-power versions. For example, their 1550 nm high-power adjustable narrowband isolator family is specified at 38 dB minimum / 42 dB typical isolation, 92% transmission, 2.3 mm maximum beam diameter, and 4 W maximum power, while larger-aperture high-power configurations reach 15 W. These specifications are for those specific models and should not automatically be attributed to IOT-G-1550A.

The IOT-G-1550A is suitable for:

• 1550 nm Laser Systems
• Free-Space Optical Isolation
• Laser Feedback Suppression
• Laser Protection
• NIR Photonics
• Optical Communication Research
• Fiber-Optic Systems
• Spectroscopy
• Interferometry
• Optical Metrology
• Laser Beam Delivery
• Optical Sensing
• LIDAR Research
• Quantum Optics
• Photonics Research
• Scientific Laser Systems

The IOT-G-1550A is particularly useful when a 1550 nm free-space laser path needs protection from unwanted reflections. It can be placed between the laser source and downstream optical components to reduce optical feedback and improve the stability of the overall laser system. For hybrid fiber/free-space setups, it can be paired with 1550 nm single-mode fiber and collimation components; Thorlabs' 1550 nm fiber products include 1550BHP single-mode fiber and 1550 nm aspheric/GRIN collimators.