IR Image upconversion using band-limited ASE illumination fiber sources

Area of Science:

• Photonics
• Optical Imaging
• Nonlinear Optics

Background:

• Upconversion imaging systems traditionally use narrowband lasers or thermal illumination.
• Narrowband lasers limit the field-of-view (FOV) due to phase-matching constraints.
• Thermal illumination offers a broad spectrum but lacks spectral intensity.

Purpose of the Study:

• To investigate the use of Amplified Spontaneous Emission (ASE) fiber sources in upconversion imaging.
• To analyze how ASE sources affect the angular acceptance and FOV of upconversion systems.
• To develop a predictive model for the upconverter's angular acceptance.

Main Methods:

• Utilizing an ASE fiber source for illuminating a transmission target in an upconversion imaging setup.
• Developing a theoretical model to predict angular acceptance based on spectral width and allocation.
• Experimentally validating the model using a 1550-630 nm upconversion process.

Main Results:

• ASE fiber sources provide higher spectral intensity than thermal sources while maintaining a broad spectrum.
• The broad spectrum of ASE sources enables larger non-collinear phase-matching angles, expanding the FOV.
• The developed model accurately predicts the angular acceptance of the upconverter.

Conclusions:

• ASE fiber sources offer a superior alternative to narrowband lasers for upconversion imaging, significantly enhancing FOV.
• The predictive model is a valuable tool for optimizing upconversion system design.
• This approach expands the applicability of upconversion imaging in various scientific fields.