Tomasz Jannson

Real-time Fourier transformation in dispersive optical fibers

The general concept of temporal Fourier transformation in dispersive media is analyzed. The real-time optical Fourier transformer is shown to be realizable by using dispersive single-mode fibers and chirping lasers.

Fiber-optic wavelength-division multiplexing and demultiplexing using volume holographic gratings

We present theoretical and experimental results of a novel fiber-optic wavelength-division multiplexing (WDM) design employing a broadband (>150-nm) dichromated gelatin volume holographic grating operating in a reflective Littrow configuration with on-axis optics, a single lens, and one fiber array. This configuration can achieve better than -1.5-dB insertion loss and -40-dB cross talk for a 6-channel system and -2.5-dB insertion loss and -20-dB cross talk for a 12-channel system with 15-nm channel spacing. For an experimental 4-channel WDM unit we measured better than -1.5-dB insertion loss for all channels and less than -32-dB cross talk. This design can provide cost and performance benefits for local area network communication applications.

Guided-wave planar optical interconnects using highly multiplexed polymer waveguide holograms

An intraplanar interconnection scheme using substrate guided modes in conjunction with a highly multiplexed waveguide volume hologram is proposed. Acoustooptically addressed 1-to-50 passive and 1-to-2-to-100 reconfigurable interconnections with a fan-out diffraction efficiency of 55% at 514-nm wavelength are demonstrated. A coordinate transformation converts the 3-D diffraction problem into a 2-D one, which significantly simplifies the theoretical calculation. Intraplane massive fan-out optical interconnection using substrate guided mode provides both collinear and coplanar fan-out capability for data and clock signals. Colinearity of signal distribution allows the 2-D input signal array to be processes. The laminated waveguide device containing a highly multiplexed dichromated gelatin (DCG) hologram has been evaluated. >

SINGLE-MODE POLYMER WAVEGUIDE MODULATOR

We report herein the first single‐mode polymer waveguide modulator which can be formed on any surface regardless of its conductivity and refractive index. These include semiconductor, conductor, and insulator surfaces. The tunability of the refractive index of the polymer film allows us to shift the guiding layer from a stepped index profile to a graded index profile. The phase‐matching condition for optical power transfer is achieved through current‐induced index modulation. Thirty‐six dB extinction ratio, which includes 3 dB absorption loss and 33 dB phase‐matched cross coupling, was observed with a current injection density of ∼1.8 μA/μm2. Unlike the conventional symmetrical dual channel coupler, the disparity of the collinear waveguide pair provides us with a much larger dynamic range of waveguide dimension suitable for generating the required phase‐matching condition and thus easing the requirement of waveguide fabrication.

Optical multiplanar VLSI interconnects based on multiplexed waveguide holograms

Optical interconnects for very large scale integration systems based on planar waveguide holograms are analyzed. The combination of low loss waveguides and multiplexed waveguide holograms allows the construction of various compact planar architectures with high interconnect density and low insertion loss. The long interaction lengths possible in planar structures result in high angular and wavelength selectivity. Holographic grating couplers and multiplexed planar holograms for 1-to-3 interconnects and 1-to-3 multiple wavelength interconnects were fabricated.

Lippmann–Bragg broadband holographic mirrors

Lippmann–Bragg broadband volume holographic mirrors, with chirp normal to the surface, represent an entirely new class of grating. These gratings are presented and analyzed theoretically by using a combination of the multiple-beam interference method and Kogelnik’s local solution for uniform gratings. Particularly noteworthy is the new grating’s combination of a very high Bragg diffraction efficiency (>99.5%) with a large tunable bandwidth (from 5 to >300 nm).

Mutual injection locking: a new architecture for high-power solid-state laser arrays

In this paper, bidirectional (mutual) injection locking is demonstrated with solid-state lasers, producing significant improvements over traditional single-direction injection locking. Each laser element shares part of its output with other elements in bidirectional locking, distinct from single-direction (traditional) injection locking where one master laser provides the locking signal for a number of slaves. In a phase-locked array, the individual laser outputs add coherently, and the brightness of the entire array scales with the square of the number of elements, as if the active material diameter were increasing. Benefits of bidirectional locking, when compared to traditional injection locking, include reduced laser threshold, better output beam quality, and improved scaling capability. Experiments using two Nd:YVO/sub 4/ lasers confirmed that mutual injection locking reduced lasing threshold by a factor of at least two and increased the output beam quality significantly. The injection-locking effects began with 0.03% coupling between lasers and full-phase locking for coupling exceeding 0.5%. The 0.5% requirement for full-phase locking is significantly lower than the requirement for traditional injection locking. The large coupling requirement limits traditional injection-locked arrays to fewer than 20 elements, whereas mutually injection-locked arrays have no such limit. Mutual injection locking of an array of lasers can lead to a new architecture for high-power laser systems.

Intraplane guided wave massive fanout optical interconnections

One‐to‐30 guided wave optical interconnections are demonstrated at 632.8 nm using a highly multiplexed waveguide volume hologram. This technology is capable of providing intrachip and intrawafer optical interconnections. The theoretical limit of the fanout number is addressed and experimentally confirmed. The measured data show that the diffracted beams have an average diffraction efficiency of 2.3% with ±0.2% variation. The demonstrated results can save surface space of electronic chips and also provide a large fanout capability due to the high index modulation of the volume hologram. Further applications based on this technology are very promising. Head‐up display, high‐speed optical data bus, surface enhanced Raman spectrometer, and optical sensors are some of the attractive ones.

45-cm long compression-molded polymer-based optical bus

We report the formation of an optical bus using compression‐molding technique. The linear dimension of such a waveguide is well beyond that of a microlithographically defined waveguide. Theoretical calculation based on the effective index method was used to determine the optimal dimension of the molding tool design for single‐ and multimode waveguides. A molded photolime gel‐based polymer optical bus with a linear dimension of 45 cm was fabricated and then tested at 0.6328‐μm wavelength. Waveguide propagation loss from 0.5 to 2 dB/cm was determined using the two prism method. As a result of this long interconnection distance, board‐to‐board optical interconnects through backplane can be realized using the technology.

Highly multiplexed graded‐index polymer waveguide hologram for near‐infrared eight‐channel wavelength division demultiplexing

An eight‐channel single‐mode wavelength division demultiplexer operating at 740, 750, 760, 770, 780, 790, 800, and 810 nm with diffraction angle varying from 16° to 44° and using a graded index (GRIN) polymer waveguide is reported for the first time. Diffraction efficiency up to 55% was measured. The wavelength spreading of the Ti:Al2O3 laser (∼4 nm, 3 dB bandwidth) causes an average crosstalk figure of −15.8 dB. The beamwidth of the diffracted signal as a function of the input beamwidth, the grating interaction length, and the diffraction angle are considered. Occurrence of the maximum value is further discussed. A waveguide lens is needed to efficiently couple the diffracted light into an output fiber whenever the diffracted beam size is beyond the core diameter of the fiber involved.