A heterogeneously integrated InGaN laser diode (LD) on Si is proposed as a path toward visible wavelength photonic integrated circuits (PICs) on Si. Herein, InGaN films are vertically stacked on a TiO2waveguide (WG) fabricated on a Si wafer by bonding. In the light propagation direction, it is composed of a hybrid InGaN/TiO2section, a TiO2WG, an adiabatic taper, and mirrors that can form a cavity. As the refractive index of GaN is well matched with that of TiO2, the optical transverse mode extends to both the GaN and TiO2in a hybrid mode. Modes between a hybrid InGaN/TiO2and a pure TiO2WG can transfer with an adiabatic taper structure. The coupling loss is calculated to be less than 0.5 dB with fairly short taper length of 78 μm and tip width of 200 nm. GaN substrate removal and bonding are critical fabrication steps of this LD and PIC. The substrate removal is successfully done by photoelectrochemical etching. Although direct bonding of GaN wafers with thermal oxide on Si is successful, GaN epitaxial wafers are more difficult. An implication and remedy of this is discussed in terms of surface roughness of GaN epitaxial film.
In this Letter, we have demonstrated wavelength beam combining (WBC) through hybrid integration of photonic integrated circuits (PICs) to significantly reduce the size, weight, and operation power of the laser combining system. The hybrid integration WBC includes III/V semiconductor optical amplifiers (SOAs), which provide gain, and the silicon nitride PICs, which perform as the external cavity. We first show that the arrayed waveguide grating (AWG) -based hybrid laser defines the lasing wavelength through the AWG passband. We then demonstrate that the AWG successfully forms multiple channel lasers by combining SOAs in the hybrid platform.
more » « less- NSF-PAR ID:
- 10201647
- Publisher / Repository:
- Optical Society of America
- Date Published:
- Journal Name:
- Optics Letters
- Volume:
- 45
- Issue:
- 22
- ISSN:
- 0146-9592; OPLEDP
- Page Range / eLocation ID:
- Article No. 6338
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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