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Journal Article
ASE-FFT-based DBR reflection spectrum reconstruction and internal reflection analysis in monolithically integrated laser diodes
- Authors
- Tae-Hyun Park, Oh-Kee Kwon, Chul-Wook Lee, Young-Sun Moon
- Issue Date
- 2025-11
- Citation
- Optics Express, v.33, no.23, pp.48717-48725
- ISSN
- 1094-4087
- Publisher
- Optica Publishing Group (formerly OSA)
- Language
- English
- Type
- Journal Article
- Abstract
- This study proposes a non-destructive method for analyzing internal reflection characteristics in a monolithically integrated tunable electro-modulated laser (TEML). An amplified spontaneous emission (ASE)–based fast Fourier transform (ASE-FFT) is applied to below-threshold spectra to obtain a distance-domain reflection map. Selective inverse FFT of the distributed Bragg reflector (DBR) section then reconstructs its intrinsic Bragg spectrum on-chip, without external light sources or interferometers. Experiments show 21% DBR reflectivity at 1542.2 nm and a ∼3.2 nm redshift of the Bragg wavelength under a 50 mA DBR current. An antireflection coating at the output facet reduces reflection by ∼11 dB, and residual active–passive interface reflections are quantified. Harmonic amplitude ratio analysis estimates cavity loss, and electro-absorption modulator bias produces absorption-induced spectral narrowing with a baseline rise in the distance-domain response. Beyond TEML, the ASE-FFT method offers a low-complexity, real-time tool for spatially resolved reflection mapping and spectral characterization of photonic integrated circuits.
- KSP Keywords
- Amplitude ratio, Bragg wavelength, Cavity loss, Distributed Bragg reflector, Electroabsorption modulator(EAM), External light, FFT method, FFT-based, Fast Fourier Transform(FFI), Integrated laser, Laser diode