Effects of annealing on performances of 1.3-μm InAs-InGaAs-GaAs quantum dot electroabsorption modulators

In this work, we investigated the effects of quantum dot (QD) annealing (as-grown, 600°C-annealed, and 750°C-annealed) on the preliminary performances of 1.3-μm InAs-InGaAs-GaAs quantum dot electroabsorption modulators (QD-EAMs). Both extinction ratio and insertion loss were found to vary inversely with the annealing temperature. Most importantly, the 3-dB response of the 750°C-annealed lumped-element QD-EAM was found to be 1.6 GHz at zero reverse bias voltage - the lowest reverse bias voltage reported. We believe that this work will be beneficial to researchers working on on-chip integration of QD-EAMs with other devices since energy consumption will be an important consideration

Multimode interference devices and integration with electroabsorption modulators for photonic integrated circuits

The multi-mode interference (MMI) device is one of the Photonic Integrated Circuit (PIC) components. By manipulating the width and length of this device, light can be split either with different power ratio, different wavelength or different polarization, all of which have been investigated. MMI also functions as a 3dB splitter, very much like a directional coupler (DC). Discussion of their similarities and advantages has been included. By combining MMI devices to other devices, more functions can be integrated together. In this dissertation, the integration of MMI and electroabsorption modulators has been investigated. This integration involved the quantum well intermixing (QWI) process. By integrating modulators to a 1xN MMI, light from a single light source can be split into N paths, and these lights can be modulated separately.DOCTOR OF PHILOSOPHY (EEE

Multimode interference devices and integration with electroabsorption modulators for photonic integrated circuits

204 p.Photonic integration is a critical emerging trend in the development of photonic devices. Its significance parallels that of the microelectronic integrated circuits (IC) albeit it has developed slower due to its diversity and often contrasting requirements. Photonic integrated circuits (PIC) is basically made up of small but important building blocks combined to realize even more complex circuits so that it may perform wider range of functionalities on optical signals used in various applications, such as optical communication, instrumentation, sensing, and signal processing.DOCTOR OF PHILOSOPHY (EEE

Optical waveguides in benzocyclobutene (BCB 4024–40) polymer

The fabrication and characterization processes of single mode optical waveguide based on photosensitive BenzoCyclobutene (BCB 4024–40) polymer are described. The polymer film thickness for various coating speed and refractive index are measured by the method of prism coupling. The waveguide is fabricated using the photolithography and chemical etching technique on BK7 glass substrate with a thin layer of SiO2 as cover. The waveguide loss is measured using the conventional cut back method which results on an average loss of 3.5 dB/cm

Polymeric Optical Splitter Based on Multimode Interference Mechanism

A 1x2 and 1x3 planar optical splitter based on BenzoCyclobutene (BCB 4024-40) polymeric material is proposed. The device is designed based on symmetric interference mechanism, utilizing a BK7 glass as a substrate and thin layer of SiO2 as a cover. Simulation results show that the splitting uniformity is better than 0.5 dB at 1550 nm optical wavelength

Multimode interference optical splitter based on photodefinable benzocyclobutene (BCB 4024-40) polymer

1×2 and 1×3 planar optical splitters based on Benzocyclobutene (BCB 4024-40) polymeric material are demonstrated for the first time. The devices are designed based on symmetric interference and fabricated on BK7 glass substrates with a thin layer of SiO2 as cover. A cost-effective chemical etching technique is used in the fabrication process to take advantage of the photosensitivity of the polymer. The waveguide loss was measured using the cutback method to be 3.5 dB/cm. The splitting uniformity is better than 0.02 and 1.5 dB at 1550-nm optical wavelength for the 1×2 and 1×3 splitters, respectively

Multimode interference wavelength multi/demultiplexer for 1310 and 1550 nm operation based on BCB 4024-40 photodefinable polymer

A 1310 and 1550 nm coarse wavelength multi/demultiplexer based on benzocyclobutene (BCB 4024-40) polymer is demonstrated for the first time. The device is designed based on a combination of general interference and paired interference mechanisms of multimode interference (MMI). It is fabricated on BK7 glass substrate with a thin layer of SiO2 as cover. A cost effective chemical etching technique is used in the fabrication process to take advantage of the photosensitive nature of the polymer. The device length was significantly reduced by adopting the restricted multimode interference scheme, lower beat length ratio and cascaded MMI couplers. The measured crosstalk at 1310 nm was 14.4 dB and at 1550 nm was 20.6 dB. The measured insertion loss is around 3.2–3.5 dB for both ports

Integration of InGaAs MOSFETs and GaAs/ AlGaAs lasers on Si Substrate for advanced opto-electronic integrated circuits (OEICs)

Lasers monolithically integrated with high speed MOSFETs on the silicon (Si) substrate could be a key to realize low cost, low power, and high speed opto-electronic integrated circuits (OEICs). In this paper, we report the monolithic integration of InGaAs channel transistors with electrically pumped GaAs/AlGaAs lasers on the Si substrate for future advanced OEICs. The laser and transistor layers were grown on the Si substrate by molecular beam epitaxy (MBE) using direct epitaxial growth. InGaAs n-FETs with an ION/IOFF ratio of more than 106 with very low off-state leakage and a low subthreshold swing with a minimum of 82 mV/decade were realized. Electrically pumped GaAs/AlGaAs quantum well (QW) lasers with a lasing wavelength of 795 nm at room temperature were demonstrated. The overall fabrication process has a low thermal budget of no more than 400 °C.NRF (Natl Research Foundation, S’pore)Published versio