Loss measurement in optical waveguide devices by coherent frequency-modulated continuous-wave reflectometry

Evaluation of losses and group effective refractive index of Er3+:Ti:LiNbO3 optical waveguides

“…The cost is relatively low in comparison, for example, to coherent frequency modulated continuous-wave reflectometry, which was used in paper [9] or exploiting fluorescence radiation or photothermal displacement, all of which require a high level of guided power.…”

High-Resolution FMCW Reflectometry Using a Single-Mode Vertical-Cavity Surface-Emitting Laser

“…F REQUENCY-MODULATED continuous-wave (FMCW) reflectometry, which is also called as optical frequency domain reflectometry (OFDR), has been developed for absolute optical ranging and for measuring reflections of fiber connectors, packaged optical devices and optical integrated devices [1]- [9]. Fig.…”

“…A Fabry-Pérot laser or a distributed feedback (DFB) laser is often used as the frequency-swept light source because the optical frequency can be easily changed by the injection current modulation or by the temperature tuning. In [1], the optical frequency of a Fabry-Pérot laser was swept by the injection current modulation and the propagation loss of a glass optical waveguide was estimated with the spatial resolution of 1 mm at 80 cm (which corresponds to 1.5 mm in air). In [2], the optical frequency of a DFB laser was tuned by the temperature tuning to achieve large optical frequency change, and the spatial resolution of 50 m in a few centimeter-long InP optical waveguide (which corresponds to about 150 m in air) was achieved.…”

Coherence enhancement of a chirped DFB laser for frequency-modulated continuous-wave reflectometry using a composite feedback loop

“…The broadband frequency noise suppression of the frequency-swept laser greatly improves its coherence, leading to a higher signal-to-noise ratio and a significantly extended measurement range in FMCW reflectometry ranging. We demonstrate a 2 mm transform-limited spatial resolution at a range window of 50 m and a 17.5 cm spatial resolution at an extended measurement range of 750 m, which is about 15 times the intrinsic laser round-trip coherence length.Optical frequency-modulated continuous-wave (FMCW) reflectometry is a promising candidate for analysis of local area networks, as well as for characterizing fiber-optic components such as fiber connectors, packaged optical devices, and optical integrated devices [1][2][3][4][5]. Lasers with high spectral purity and a large tuning range are important for coherent FMCW reflectometry, as the maximum range is limited by the coherence length of the laser and the spatial resolution is inversely proportional to the frequency tuning span.…”

“…Optical frequency-modulated continuous-wave (FMCW) reflectometry is a promising candidate for analysis of local area networks, as well as for characterizing fiber-optic components such as fiber connectors, packaged optical devices, and optical integrated devices [1][2][3][4][5]. Lasers with high spectral purity and a large tuning range are important for coherent FMCW reflectometry, as the maximum range is limited by the coherence length of the laser and the spatial resolution is inversely proportional to the frequency tuning span.…”