A Packaged Flattened Broadband Amplified Spontaneous Emission Source

ABSTRACT Flattened amplified spontaneous emission sources are critical for high‐precision optical metrology due to their broadband, stable, and spectrally flat output. However, such sources have remained predominantly fiber‐based. Here, an integrated chip‐scale photonic module based on an erbium‐doped thin‐film lithium niobate (Er: TFLN) platform is demonstrated, achieving stable and spectrally flat broadband emission. Unlike previous chip‐scale ASE demonstrations that suffered from poor spectral uniformity or lacked practical packaging, the present module integrates a custom‐designed linearly chirped fiber Bragg grating with a fiber array packaging technology. The device exhibits spectral flatness below 2.97 dB over a 30 nm wavelength range (1540–1570 nm) and exceptional stability, with power variation less than 50 nW over 50 min. The packaged module measures only 10 mm × 2.2 mm in chip size and is fully fiber‐coupled, enabling direct integration into miniature precision systems. This work represents a crucial step toward miniaturized, robust broadband sources for demanding applications such as aerospace navigation, portable sensing, and optical coherence tomography.