Short-range optical interconnection is more emphasizing in high performance systems. Multimode waveguide array is considered as a major interconnection medium due to the relatively easy packaging with devices. The multimode fiber array conjunction with VCSEL and Pin photodiode array is widely used in board to board and/or system to system interconnection. We demonstrate a flexible optical waveguide film which was composed of VCSEL, photodiode array, multimode waveguide array and 45 degree micro mirror couplers. The flexible waveguide film has many potentials such as it can be integrated with typical rigid electronic board and free from geometrical constraint. The waveguide film with 45° mirror was fabricated on a flexible transparent substrate using soft molding technique and then thin film VCSEL and photo-detector array are integrated. Master structure of the waveguide, which has multimode waveguide array and 45° mirror structure was fabricated using conventional lithography and microtome technique.
We introduce a fully embedded board level guided-wave optical interconnects for short range optical interconnects. The realization of the fully embedded optical interconnects is achieved by overcome several difficulties such as thermal management of a VCSEL, thin film VCSEL fabrication, effective coupling and materials selection. A novel heat sink structure for cooling is developed to solve thermal management. We fabricated 10micron-thick linear VCSEL arrays and MSM detector array. As a physical layer, flexible optical interconnection layer incorporated with channel waveguides and 45° waveguide mirror couplers are also fabricated using compression molding technique.
A fully embedded board-level guided wave optical interconnection is presented to solve the packaging compatibility problem. All elements involved in providing high speed optical communications within a board are demonstrated. Experimental results on a 12-channel linear array of polymeric waveguides, thin film VCSELs (10 μm), and GaAs MSM photodetectors suitable for a fully embedded implementation are provided. By embedded approach, all the real estate of the PC board surface are occupied by electronics so that one only observes the performance enhancement due to the employment of optical interconnection without any interface problems between electronic and optoelectronic components. Thin film 1X12 linear array VCSEL and GaAs MSM detector were demonstrated and thermal management issue of the VCSEL in the fully embedded scheme was discussed.
The design and integration of a fully embedded Si-CMOS process-compatible optical interconnects are presented. The transmitting and receiving functions will be incorporated within the embedded optoelectronic interconnection layers of 3-D integrated multilayer boards and ASICs. All elements including waveguide, coupler, detector and laser for the fully embedded board-level optical interconnection system are developed. The propagation loss of waveguide is 0.58 dB/cm at 632.8 nm and 0.21 dB/cm at 850 nm. The 45-degree TIR (total internal reflection) micro-mirror couplers with high coupling efficiencies are formed by reactive ion etching. The MSM (metal-semiconductor-metal) photo-detector array is fabricated on a GaAs wafer by a CMOS compatible technique. The external quantum efficiency of 0.4 A/W and 3 dB bandwidth of the integrated MSM photo-detector of 2.648 GHz are experimentally confirmed. The VCSEL array with a sacrificial layer for the epitaxial liftoff of VCSEL from the GaAs substrate is designed and manufactured. A 1 X 12 array of VCSELs, MSM photo- detectors and polyimide channel waveguides via 45-degree TIR micro-couplers are integrated on Si wafer. The experimental performances of the highly integrated system are given.
We report the design and formation of a high-performance polymer waveguide array with 45-degree micro-mirror couplers for achieving fully-embedded board-level optoelectronic interconnects. We have used Si CMOS process compatible polymer as the fabrication material, which is relatively easy to process and has low propagation loss at 850 nm wavelength. 45-degree total interior reflection micro-mirror couplers fabricated within the channel waveguides provide surface-normal light coupling between the waveguide and the optoelectronic devices, thus forming a fully-embedded 3D optoelectronic interconnect. We have demonstrated a hybrid optoelectronic integrated system of GaAs MSM photodetector array and polymer channel waveguide array with 45-degree micro-mirror couplers, showing an aggregate 3 dB bandwidth of 32 GHz.
A demonstration of hybrid integration of a 1 X 12 metal- semiconductor-metal (MSM) photo-detector array and polyimide channel waveguides via 45 degree(s) total-internal-reflection micro-coupler is reported here. MSM photo-detector array was fabricated on a semi-insulated GaAs wafer. The two-layer polyimide waveguide array was constructed using Ultradel 9120D for core and Ultradel 9020 for lower cladding layer. The photodetectors are integrated to operate in the conventional vertical illumination mode. We have measured the external quantum-efficiency and 3 dB bandwidth of the integrated MSM photo-detectors to be 0.4 A/W and 2.648 GHz, respectively. The aggregate 3 dB bandwidth of the 12-channel integrated system is 32 GHz.
We report the fabrication and processing of thin film MSM silicon photo-detector and thin film VCSEL for optoelectronic interconnects. These two components, together with polyimide wave-guide can be used in constructing the high sped, low power, low cost optical interconnection system. Such a system will provide the fast board level data transmission. The DC and AC characteristics of thin film silicon MSM photo-detector, and the I-V and L-I characteristics of thin film VCSEL are measured.
We report the formation of high-performance polyimide waveguide arrays with 45 degree(s) micro mirror coupler fabricated at each end, which provides a high-efficiency output or input surface-normal light couple for the waveguide. This fully embedded integration provides an efficient method of optical interconnection for the board-level data communication and the multi-layer connection. We employed the Si CMOS process compatible polyimide as the fabrication material, which is relatively easy to process and has low propagation loss for light at 850 nm wavelength. A 1 X 12 waveguide array with 45 degree(s) micro mirror coupler fabricated at each end is experimentally demonstrated.
We report the formation of polyimide-based H-tree waveguides for a multi-GBit/sec optical clock signal distribution in a Si CMOS process compatible environment. Such a clock distribution system is to replace the existing electronic counterpart associated with high-speed supercomputers such as Cray T-90 machine. A waveguide propagation loss of 0.21 dB/cm at 850 nm was experimentally confirmed for the 1-to-48 waveguide fanout device. The planarization requirement of the optical interconnection layer among many electrical interconnection layers makes the employment of tilted grating a choice of desire. Theoretical calculation predicts the 1-to-1 free-space to waveguide coupling with an efficiency as high as 95 percent. Currently, a coupling efficiency of 35 percent was experimentally confirmed due to the limited index difference between guiding and cladding layers. Further experiments aimed at structuring a larger guiding/cladding layer index differences are under investigation. To effectively couple an optical signal into the waveguide through the tilted grating coupler, the accuracy of the wavelength employed is pivotal. This makes the usage of the vertical cavity surface-emitting lasers (VCSELs) and VCSEL arrays the best choice when compared with edge-emitting lasers. Modulation bandwidth as high as 6 GHz was demonstrated at 850 nm. Such a wavelength is compatible with Si-based photodetectors.
Guided-wave optics is a promising way to deliver high-speed clock-signal in supercomputer with minimized clock-skew. Si- CMOS compatible polymer-based waveguides for optoelectronic interconnects and packaging have been fabricated and characterized. A 1-to-48 fanout optoelectronic interconnection layer (OIL) structure based on Ultradel 9120/9020 for the high-speed massive clock signal distribution for a Cray T-90 supercomputer board has been constructed. The OIL employs multimode polymeric channel waveguides in conjunction with surface-normal waveguide output coupler and 1-to-2 splitters. Surface-normal couplers can couple the optical clock signals into and out from the H-tree polyimide waveguides surface-normally, which facilitates the integration of photodetectors to convert optical-signal to electrical-signal. A 45-degree surface- normal couplers has been integrated at each output end. The measured output coupling efficiency is nearly 100 percent. The output profile from 45-degree surface-normal coupler were calculated using Fresnel approximation. the theoretical result is in good agreement with experimental result. A total insertion loss of 7.98 dB at 850 nm was measured experimentally.
A new method of using a weak-feedback grating external cavity to improve the output characteristics of visible light semiconductor laser was studied and proved to be practical. The experiment has been conducted to apply this method on 650 nm semiconductor laser. A blazed grating is used as the external cavity mirror to narrow the linewidth and select frequency. Through turning the grating, we obtained laser output with single longitudinal mode and linewidth as narrow as 0.1 pm, of which the linewidth reduction rate is 9800. The tuning range of wavelength is about 5 nm out of 20 nm fluorescent spectrum, and the side mode suppression ratio is ideal. Confocal Fabry-Perot interferometer and spectroscopy were used to measure the linewidth and frequencies. Proposals to improve the experimental results are raised.
An all fiber Q-switched laser with Mach-Zehnder Interferometer configuration has been reported. A fiber Bragg grating is used to achieve frequency-choice and tuning. The laser can generate stable optical pulse at center wavelength 1561nm, peak power 2.6w, pulse width 4.2?s at repetition rate 760Hz, pumped by a laser diode 980nm. Self-mode locking in the Q- switched all fiber laser has been demonstrated. If changing period of fiber grating through adjusting stress or temperature, we can obtain continuous wavelength tunable output optical pulse and the tunable range is about 5nm.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.