Daisuke Shimura

Bidirectional optical subassembly with prealigned silicon microlens and laser diode

We have succeeded in developing a low-cost bidirectional optical subassembly chip using a silicon microlens for fiber-to-the-home application. The main optical elements of the bidirectional function were automatically aligned and integrated on a silicon optical bench. The cost of subassembly was markedly lowered both by reducing the part number and simplifying the assembly process. The prototype bidirectional optical component was successfully fabricated on the basis of the proposed chip. A receiver minimum sensitivity of -28.5 dBm was experimentally demonstrated even at 75 degC

Surface-mountable silicon microlens for low-cost laser modules

A surface-mountable silicon microlens that can be passively aligned in a silicon V-groove is proposed. The microlens has a diffractive optical element on the end facet of a semicylindrical structure whose diameter is identical to that of a single-mode fiber (SMF). The experimental result of coupling efficiency between a distributed feedback laser diode and SMF shows low loss (-3.0 dB) as determined using the microlens. Monte Carlo simulations indicate that the microlens is suitable for low-cost and high-performance optical modules for metro networks.

A low-cost micro-BOSA using Si microlens integrated on Si optical bench for PON application

We propose single TO-CAN type bi-directional optical subassembly in which. LD, PD chips, filter and Si microlenses are passively integrated on Si optical bench. High performance such as minimum sensitivity of -28 dBm was experimentally demonstrated.

A low cost PON transceiver using single TO-CAN type micro-BOSA

A novel low-cost small-form-factor (SFF) optical transceiver using a micro-compact bi-directional optical sub-assembly (micro-BOSA) for passive optical network (PON) application is proposed. In this micro-BOSA, optical transmitting and receiving functions are incorporated in a single TO-CAN package. The BOSA is compact and its pin assignment provides fine connection to printed circuit board and fit in transceiver housing. Bi-directional optical transmission at 1.25Gbit/s with the receiver minimum sensitivity of -28.2dBm is demonstrated for the fabricated transceiver with the proposed micro-BOSA

Mach-Zehnder filter using multiple Si waveguide structure sections for polarization independence and improved fabrication/temperature tolerance

We report the design of the Mach-Zehnder interferometer wavelength filter using multiple Si waveguide structure sections. Tolerance to width error, temperature shift and polarization independence can be attained.

Polarization rotation Bragg diffraction using Si wire waveguide grating and polarization rotator

We report polarization independent Bragg grating wavelength filter with high diffraction efficiency. A rib waveguide polarization rotator and antisymmetric grating structure for fundamental to first order diffraction are used to generate the polarization rotation Bragg diffraction. The diffraction efficiencies and peak wavelengths become the same for two orthogonal input polarizations. Strong diffraction is attained easily. The concept was verified by simulation and experiment. Polarization independent band-pass filter consisting of polarization beam splitter and polarization rotation Bragg diffraction was experimentally demonstrated.

Ultra compact optical subassembly using integrated laser diode and silicon microlens for low-cost optical component

We have succeeded in developing an ultra compact optical subassembly (OSA) that consists of a pre-aligned Si microlens and a laser diode (LD) integrated on a Si V-groove substrate with a footprint less than 1 mm by 1 mm. This OSA is small enough to be mounted on a TO-CAN package such as TO38, making the resulting optical component ultra compact in size and reducing the packaging process cost. A coupling efficiency better than -2.6 dB between the OSA and a single-mode fiber (SMF) has been experimentally confirmed. The experimental results show the OSAs applicability to metro networks, making the OSA a promising candidate for low-cost and high-performance optical components.

Optical Feedback-Tolerant 1.3 μm Gain-Coupled DFB lasers for isolator-free micro-BOSA modules

Gain-coupled (GC)-DFB-LD tolerant to optical feedback was developed for low-cost, isolator-free optical subassembly module. GC-DFB-LD into isolator-free micro-BOSA module has power penalty less than 0.3 dB after 25 km transmissions at 1.25 Gb/s with -15 dB optical feedback.

Silicon microlens on V-groove platform for low-cost and high-performance optical modules

We succeeded in developing the prototype Si microlens that is applicable to the surface mount technology (SMT) using Si V-groove substrate. The diameter of the fabricated Si microlens was identical to that of SMF. The Si microlens was successfully picked and placed on the V-groove substrate, realizing automatic alignment between the microlens and SMF by sharing the same V-groove. The microlens has an ability to achieve the coupling efficiency as high as -3.0 dB between DFB-LD and SMF. The designed microlens can realize collimated beam, so that any functional elements such as an isolator are integrated on the Si V-groove substrate, making the SMT with a Si Vgroove a universal platform suitable for mass-producible low

Silicon waveguide polarization rotation Bragg grating with chirp, phase shift section or super-structure grating scheme

We describe a Bragg grating with phase shift section, chirp or super-structure grating scheme that converts the input polarization to orthogonal polarization. A very narrow polarization independent wavelength peak can be generated by phase shift structures and multiple diffraction peaks by sampled or super-structure gratings. Polarization independent flat-top response was obtained experimentally by chirped grating.