Tapered rib adiabatic following fiber couplers in etched GaAs materials for monolithic spot-size transformation
- Resource Type
- Periodical
- Authors
- Vawter, G.A.; Sullivan, C.T.; Wendt, J.R.; Smith, R.E.; Hou, H.Q.; Klem, J.F.
- Source
- IEEE Journal of Selected Topics in Quantum Electronics IEEE J. Select. Topics Quantum Electron. Selected Topics in Quantum Electronics, IEEE Journal of. 3(6):1361-1371 Dec, 1997
- Subject
- Engineered Materials, Dielectrics and Plasmas
Photonics and Electrooptics
Optical fiber couplers
Etching
Gallium arsenide
Optical waveguides
Semiconductor waveguides
Optical modulation
Fiber lasers
Laser modes
Semiconductor lasers
Waveguide lasers
- Language
- ISSN
- 1077-260X
1558-4542
Design details and demonstration data are presented for an (Al,Ga)As monolithic tapered rib waveguide achieving modal spot-size transformation. The tapered rib adiabatic following fiber coupler structure (TRAFFIC) achieves two-dimensional (2-D) expansion of the output optical mode of single-transverse-mode semiconductor waveguide modulators and lasers using a one-dimensional (1-D) taper between noncritical initial and final taper widths which are compatible with optical lithographic techniques. Measurements are presented of total mode expansion losses between /spl sim/1.5-2.0 dB and semiconductor to single-mode-fiber waveguide coupling losses of /spl sim/0.5-1.0 dB for doped pin optical-modulator-type waveguides using the TRAFFIC waveguide. A semiconductor laser with a TRAFFIC tapered-rib mode-expansion section and measured coupling loss between the laser output and single-mode fiber of only 0.9 dB is described. Finally, a TRAFFIC Spot-size transformer for undoped waveguide modulators with total mode expansion losses of 1.84 dB and excellent modal behavior at 1.32-/spl mu/m wavelength is presented. The TRAFFiC structure is particularly well suited for integration with both active and passive etched rib waveguide devices. Fabrication is relatively simple, requiring only patterning and etching of the tapered waveguide and uniform-width outer mesa waveguide without any epitaxial regrowth.