TeraXion (Canada)

An array of 18 FBGs spectrally distributed over 70 nm was written in a polyimide-coated fiber, with a single uniform phase-mask, by applying strain on the fiber prior to exposition. This flexible method will be used to develop directional sensor for distributed sensing based on a hybrid glass-polymer multicore fiber.

Radio-frequency (RF) photonics is demonstrating superior performance in communication systems using discrete components. As systems establish an upgrade path balancing challenging bandwidth requirements with size, weight, and power constraints, the time is ripe for transition to a more efficient and cost-effective hybrid manufacturing technology. This technology has been applied to the construction of an optical coherent receiver for the down conversion of RF signals from 10–18 to 2 GHz. Light from a distributed feedback semiconductor laser is split between two lithium niobate Mach-Zehnder modulators, driven either by a tunable local oscillator tone or an RF signal coming, for example, from a receiving antenna. The modulated light signals are combined with an optical coupler and filtered by two fiber Bragg gratings that select one optical sideband from each signal. Detection of the filtered light by a balanced photo-detector produces an electrical signal at an intermediate frequency equal to the beat difference between the frequencies of the RF signal and the local oscillator. Packaging of optical and opto-electronic components within a common enclosure where light routing is performed by micro-optics has allowed a significant decrease in the size, weight, and power consumption of the receiver.

A compact three-laser source for optical sensing is presented. It is based on a low-noise implementation of the Pound-Drever-Hall method and comprises high-bandwidth optical phase-locked loops. The outputs from three semiconductor distributed feedback lasers, mounted on thermo-electric coolers (TEC), are coupled with micro-lenses into a silicon photonics (SiP) chip that performs beat note detection and several other functions. The chip comprises phase modulators, variable optical attenuators, multi-mode-interference couplers, variable ratio tap couplers, integrated photodiodes and optical fiber butt-couplers. Electrical connections between a metallized ceramic and the TECs, lasers and SiP chip are achieved by wirebonds. All these components stand within a 35 mm by 35 mm package which is interfaced with 90 electrical pins and two fiber pigtails. One pigtail carries the signals from a master and slave lasers, while another carries that from a second slave laser. The pins are soldered to a printed circuit board featuring a micro-processor that controls and monitors the system to ensure stable operation over fluctuating environmental conditions. This highly adaptable multi-laser source can address various sensing applications requiring the tracking of up to three narrow spectral features with a high bandwidth. It is used to sense a fiber-based ring resonator emulating a resonant fiber optics gyroscope. The master laser is locked to the resonator with a loop bandwidth greater than 1 MHz. The slave lasers are offset frequency locked to the master laser with loop bandwidths greater than 100 MHz. This high performance source is compact, automated, robust, and remains locked for days.

We describe herein an unprecedented mechanochemical "parallel synthesis" of 3,4-dihydro-2H-benzo[e][1,3]oxazine derivatives via a one pot three component reaction. The new milling system uses a multiposition jar (variable sizes are possible), allowing for the processing of up to 12 samples simultaneously, leading to the formation of a fungicide and a building block for polymer preparation with higher throughput compared to standard milling devices.

We demonstrate PAM-4 and OOK operation of a novel silicon photonic modulator. The modulator design is based on two phase-shifts in a Bragg Grating structure driven in a push pull configuration. Back-to-back PAM-4 modulation is demonstrated below the FEC threshold at up to 60 Gb/s. OOK modulation is also shown up to 55 Gb/s with MMSE equalization and up to 50 Gb/s without equalization. Eye diagrams and BER curves at different bit rates are provided for both PAM-4 and OOK modulations. To our knowledge, this structure is the fastest silicon photonic modulator based on Bragg gratings, reaching modulation speed comparable to the fastest Mach-Zehnder modulators and micro-ring modulators.

A Bragg grating SiP modulator operated at 50 Gb/s with BER below the FEC threshold is demonstrated using OOK modulation without equalization. To date, this work presents the fastest SiP modulator using Bragg gratings structures.

TeraXion started silicon photonics activities aiming at developing building blocks for new products and customized solutions. Passive and active devices have been developed including MMI couplers, power splitters, Bragg grating filters, high responsivity photodetectors, high speed modulators and variable optical attenuators. Packaging solutions including fiber attachment and hybrid integration using flip-chip were also developed. More specifically, a compact packaged integrated coherent receiver has been realized. Good performances were obtained as demonstrated by our system tests results showing transmission up to 4800 km with BER below hard FEC threshold. The package size is small but still limited by the electrical interface. Migrating to more compact RF interface would allow realizing the full benefit of this technology.

In the evaluation a fused biconical taper 1480/1580 nm WDM's ability to handle high power cascaded Raman laser throughput (>100 W) a significant degradation in performance was observed. A systematic root cause investigation was conducted and it is experimentally confirmed that the WDM degradation was caused by an interaction between the high power 1480 nm line, an out-of-band Stokes line, and the -OH content of the glass optical fiber. Slanted fiber Bragg grating (SFBG) was introduced to filter out the 1390 nm out-of-band Stokes line in an attempt to avoid this interaction. Ultimately a series of tests were conducted and it was confirmed that the addition of a 1390 nm SFBG in between a high power Raman laser and the high power WDM has successfully prevented the degradation which therefore allowed the continued high power operation of the WDM. NAVAIR Public Release SPR 2013-469 Distribution Statement A-"Approved for Public release; distribution is unlimited".

We experimentally show optically filtered lasers reduce OSNR penalty due to phase tracking error up to 3 dB for two parallel decision directed algorithms with feedback delay in an 11 Gbaud/s 16QAM coherent system.

Fourier domain mode locked (FDML) lasers provide high sweep rates, broad tuning ranges, and high output powers for optical coherence tomography (OCT) systems. However, presently-known FDML lasers at 1300 nm have relatively short coherence lengths, limiting the size of samples that can be imaged. Furthermore, FDML lasers produce only one useable sweep direction. We report FDML coherence length extension by incorporating advanced dispersion compensation modules (DCMs). DCMs eliminate group velocity dispersion in the cavity, doubling coherence lengths and ensuring uniform axial resolution over the imaging range. Additionally, forward and backward sweeps are nearly identical, removing the need for external buffering stages.