Nineteen-port photonic lantern with multimode delivery fiber

Area of Science:

• Photonics
• Astrophysics
• Optical Engineering

Background:

• Astrophotonics requires efficient coupling of multimode (MM) starlight into single-mode (SM) fibers for advanced spectral analysis.
• Traditional setups necessitate placing beam splitters directly at telescope focal planes, posing integration challenges.
• Photonic lanterns offer a potential solution for MM-to-SM conversion, but efficiency and practical implementation need further study.

Purpose of the Study:

• To demonstrate efficient multimode (MM) to single-mode (SM) conversion using a 19-port photonic lantern.
• To evaluate the photonic lantern's utility in astrophotonics for spectral filtering applications.
• To assess the coupling losses associated with the MM-to-SM conversion and its integration with telescope systems.

Main Methods:

• Utilized a 19-port photonic lantern for MM-to-SM light conversion.
• Employed a 50 μm core multimode delivery fiber for coupling light to the photonic lantern.
• Measured coupling losses for light transitioning from an MM fiber to an ensemble of 19 SM fibers and back to an MM fiber.

Main Results:

• Achieved efficient MM-to-SM conversion with the 19-port photonic lantern.
• Demonstrated low coupling loss below 1.1 dB for the round-trip MM fiber to SM fiber ensemble.
• Showcased the photonic lantern's capability to decouple the spectral filtering unit from the telescope's focal plane via the delivery fiber.

Conclusions:

• The 19-port photonic lantern provides an effective solution for MM-to-SM conversion in astrophotonics.
• The use of an MM delivery fiber simplifies instrument design by removing the need for focal-plane-mounted splitters.
• This technology facilitates fiber-Bragg-grating-based spectral filtering for astronomical observations with reduced coupling losses.