Inscription of type I and depressed cladding waveguides in lithium niobate using a femtosecond laser
| Autor: | Anuj Bhatnagar, R. Bernard, Deepak Mathur, J. A. Dharmadhikari, S. P. Bhardwaj, Aditya K. Dharmadhikari, Kshitij Mittholiya |
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| Rok vydání: | 2017 |
| Předmět: |
Multi-mode optical fiber
Materials science business.industry Lithium niobate 02 engineering and technology 021001 nanoscience & nanotechnology Laser Cladding (fiber optics) 01 natural sciences Atomic and Molecular Physics and Optics law.invention 010309 optics chemistry.chemical_compound Optics chemistry law Fiber laser 0103 physical sciences Femtosecond Electrical and Electronic Engineering 0210 nano-technology business Engineering (miscellaneous) Waveguide |
| Zdroj: | Applied optics. 56(20) |
| ISSN: | 1539-4522 |
| Popis: | We describe two types of waveguides (type I and depressed cladding) inscribed in lithium niobate using a variable repetition rate (200 kHz–25 MHz), 270 fs duration fiber laser. The type I modification-based waveguides have propagation losses in the range from 1.2 to 10 dB/cm at 1550 nm, depending on experimental parameters. These waveguides are not permanent; they deteriorate over time. Such deterioration of waveguides can be slowed down from 30 days to 100 days by pre-annealing the samples and by writing at a 720 kHz laser repetition rate. The propagation losses measured at 1550 nm show significant improvement for pre-annealed samples. The depressed cladding-inscribed waveguides are permanent, but the propagation loss depends on the number of damage tracks. A track separation of ∼1 μm between adjacent damage tracks yields the lowest propagation loss of 0.5 dB/cm at 1550 nm for a 40 μm diameter waveguide. We observe multimode guidance for sizes in the range of 20–80 μm in these waveguide structures at 1550 nm. Their crystalline nature is found to remain intact, as inferred from second-harmonic generation within the waveguide region. |
| Databáze: | OpenAIRE |
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