Integrated solid-state lasers have the advantage of offering narrow linewidth, well below the MHz range, making them ideal for various applications, from sensing to telecommunication. High coherence free-running lasers are difficult to characterize, due to the combination of a reduced linewidth with potential frequency drift. Conventional techniques such as optical self-heterodyning solutions require decorrelation lengths of several hundreds of km, and standard RF phase noise measurements are not compatible with slow varying effects due to the presence of frequency drift. In order to analyze the coherence of ion-exchanged co-doped Er-Yb integrated glass lasers during free-running operations, we developed a direct measurement of the optical phase by analyzing heterodyne signals in the time domain. From the analysis of the phase evolution in time, we estimate the linewidth of ion exchange glass lasers, estimated to be 1 kHz, while being able to discriminate optical contributions from slow varying processes generating frequency drift.

Erbium-doped amplifiers are key elements not only for modern telecom systems but also for integrated narrow linewidth lasers that are used for sensing and THz generation. Ion exchange on glass is a technological platform that allows realizing very efficient erbium-doped waveguide amplifiers with low coupling losses and quite high net gains. However, integrated lasers require a shorter amplifying waveguide that is operated in a strongly saturated regime. For this reason, a co-doping with Er and Yb is used. In this paper, we present the characterizations of Er-Yb co-doped waveguide amplifiers in terms of spectroscopic and guiding properties. Then small signal and satured gains measurements are presented. Finally, all these experimental data are employed to derive and assess a theoretical model of the ion-exchanged waveguide amplifier.

In this Letter, we propose an approach to improve the packaging of electro-optical transceivers based on silicon photonics through the development of a glass interposer. This assembly platform integrates polymer optical waveguides and an integrated turning mirror that vertically redirect the optical signal in the plane of the interposer to the grating coupler of a flip-chipped photonic integrated circuit (PIC). A distinctive feature of the proposed packaging scheme is to use a conventional flip-chip technique without active alignment. Functionalities are completed with a copper redistribution layer that supports the routing of DC to millimeter wave (mmW) signals to drive the PIC. The measured loss in polymer waveguides is 1.92 dB/cm at 1310 nm, and the coupling losses associated with light propagation through the turning mirror and the PIC grating coupler are 18.7 dB. Coplanar mmW waveguides are structured on the glass interposer by cold laser ablation, yielding an attenuation of 0.3 dB/mm at 58 GHz. The most important outcome of this work is that the coupling of the optical signal from the interposer to the PIC is experimentally established. We also assessed the mmW performance of coplanar waveguides through the validation of the interposer to PIC and PIC to the interposer transition.

Terahertz applications have been extensively studied during the last decade since they allow not only increasing the bandwidth of telecom systems but also the detection of many organic molecules in solid and liquid phase, including hazardous materials such as explosives. In this contribution, we present a device that allows generating frequencies in the Terahertz domain through the heterodyning of signals emitted by two distributed feedback lasers made by ion exchange on a erbium-ytterbium co-doped glass. Thanks to the intrinsic thermal stability of the glass substrate, the slow dynamic of the amplifier medium and since the laser pairs are integrated on a single chip and identically pumped by the same sources, stable frequencies have been generated in the millimeter and sub-Terahertz frequency range, without any thermal or electrical control loop being implemented.

Lasers on glass exhibit thermal stability and a very narrow linewidth compatible with frequency generation. In this work, we report the fabrication of single-mode co-integrated lasers on the same Er:Yb doped glass substrate. By modifying the laser design, optical frequencies separated by 50 to 280 GHz have can be generated having milli-watts optical power. Such signals can be converted to THz signal using a wide bandwidth photodiode. THz beating frequencies up to 280 GHz are reported in these preliminary results. In this work, we demonstrated the first THz source made of co-integrated Erbium-doped DFB laser. A maximum power of 140 nW at 140.0 GHz was measured, with a conversion efficiency of 7%.

This work presents a radiofrequency (RF) performance review of a conductive ink dispensing process for RF applications. This innovative process allows to functionalize existing objects like plastic cases for adding a RF function. It can print devices on a substrate placed horizontally or in a tilted position. The main purpose of this work consists in showing the feasibility of this process. First, Coplanar transmission lines are printed with silver ink on horizontal substrate by a simple configuration. It exhibits a performant attenuation coefficient: α4GHz=0.021±0.007 dB/mm. In a second part, a 6-axis robot is used for improving the 3D process, coplanar transmission lines are also printed and exhibit a performant attenuation coefficient: α4GHz=0.060±0.009 dB/mm. Finally, coplanar lines are printed on tilted plastic substrate and then measured. The scattering parameters of horizontal and tilted substrates are similar and exhibit a good performance in the range of 0 to 4 GHz.

Erbium-doped integrated DFB lasers on glass exhibit a thermal stability and a very narrow linewidth that has been proven useful for many applications ranging from DWDM and Optomicrowave transmissions to airborne LIDAR. If the technologies used for the Erbium-doped active waveguides can differ (alumina, phosphate and silicate glasses have been reported among others), the laser cavity is always obtained thanks to a long Bragg grating implemented on the chip surface. Realizing cm-long submicrometric structure is a challenge that has been successfully overcome, but having such fragile features exposed on the top of a device entails several problems of packaging when reliability is concerned. Until now, this key issue has been addressed by depositing a conformal thin-film on the device surface, which is a complicated task since the deposited layer should be conformal, match the proper refractive index and respect the thermal budget of the process flow. In this paper, we present a different approach for the realization of Er-doped DFB lasers on glass where the grating-based cavity is implemented on a passive wafer that is then flip-chipped and wafer bonded on an Erbiumdoped phosphate glass containing active ion-exchanged waveguides. First results proved that a stable emission at a wavelength of 1.55 μm has been achieved for a fiber-coupled output power of more than 1mW.

Silicon ring resonators on SOI substrates are well known and widely studied devices for silicon photonics-based systems. They are commonly used in datacom and highperformance computing for wavelength multiplexing, modulation and spectral filters. They can be tuned to the desired frequency with resistive heaters, which is the primary power budget of the device. In this work, backside cavities have been successfully etched in the bulk of the SOI substrate below ring resonators to improve heat trapping within the silicon rings. Simulations show that those backside cavities improve significantly heat confinement and minimizes locally heat losses due to conduction in the Si substrate. All the processes used in this study are compatible with the standard silicon photonics interposer process flow. A 72% power consumption reduction for a 10 μm diameter ring resonator on SOI has been achieved with a backside opening of 100 μm deep and 40 μm diameter, in good agreement with simulation results. Most importantly, the cavities opening did not impact the optical performances of the ring. Dynamic behavior of the rings was also studied, and show that the presence of cavities increases the thermal switching time of the rings.

The ohmic curing of two silver micro-particle inks was studied. Silver lines of 35 to 75 µm thick were printed on a mixture of polycarbonate and acrylonitrile butadiene styrene (PC+ABS) substrate and on a mineral reinforced Nylon 6 thermoplastic, using a laboratory-made system based on a volumetric dosing dispenser. After 48 h of stabilization in ambient conditions, a current is applied through the printed lines with an imposed intensity value and application time in order to cure the silver inks. Evolutions of the temperature and the resistivity of silver tracks were followed during the process. Printed thermoplastics were characterized at the end of the process in order to check the absence of deformation due to the curing treatment. The study showed that the ohmic curing led to better electrical performances than an oven process with a considerable time saving. Most of the printed line resistivity drop occurred in the first 30 s of the treatment. The ohmic curing induced a local increase of temperature located in the printed line and avoided damaging the substrates, which makes the process compatible with thermal sensitive substrates. Therefore, the ohmic curing is an efficient low-cost process to cure silver micro-particle inks that could be easily implemented at an industrial scale. Graphic abstract

Ion-exchange on glass is one of the major technological platforms that are available to manufacture low-cost, high performance Planar Lightwave Circuits (PLC). In this paper, the principle of ion-exchanged waveguide realization is presented. Then a review of the main achievements observed over the last 30 years will be given. The focus is first made on devices for telecommunications (passive and active ones) before the application of ion-exchanged waveguides to sensors is addressed.

In the framework of High Performance Computing and Datacom, silicon photonics interposers propose an interesting approach, while providing new challenges. This paper demonstrates such an integration and focuses on TSV Mid integration impact on sensitive photonic structures such as ring modulators, focusing on two specific technological aspects: substrate thinning and TSV integration. It is shown that thinning down to 100 microns and integrating TSV do not impact photonic performances more than wafer level process variability. Finally, thanks to these results, 3D Si photonics design opportunities will be discussed.

Performance degradations of Silicon Photonics (SP) high speed photodetector represent a major issue for the reliability of these devices. An explanation of these degradations is presented based on both electrical characterization and device modelling. The observed degradations of both dark current and responsivity can indeed be modeled by a single carrier lifetime degradation, attributed to an increase of the surface recombination rate, impacting an unexpected large contribution of diffusion in the photocurrent. The results obtained with this model are experimentally confirmed by extracting the activation energy of the dark current, before and after stress. The improved physical understanding of the degradation is expected to lead to shorter test protocols for SP devices.

Recently, dual mode lasers proved to be interesting sources for radio frequency generation at millimeter wave frequency and beyond, to be used in photonic RoF systems. As the optical modes can eventually be correlated, such sources associate the simplicity of heterodyning technique with the frequency stability. Still, most architectures require active frequency control loop to reach communication requirements to limit frequency drift, and reduce the phase noise of the generated carrier. In this communication, we propose the use of a free running dual mode laser integrated on glass for radio frequency generation. The device is fabricated on an ion-exchanged co-doped Erbium Ytterbium substrate to emit in the C-band. We demonstrate that this device is able to generate an ultra-narrow spectrum radio-frequency carrier, reaching 600Hz spectral linewidth without control loop nor thermal stabilization. As a proof of concept, the device proposed in this work produces a radio frequency at 6.1 GHz which has been evaluated as an electrical carrier in radio transmission experiments. Data rates of several Gbps using complex modulation formats such from BPSK to 64QAM have been successfully tested. The results are compliant with communications standards requirements, validating the use of such a source in Radio over Fibre (RoF) systems. This paper first presents the glass dual-mode laser design, followed by the characterization of the generated carrier to finally present the radio over fiber results.

Rare-earth ion doped potassium yttrium double tungstate, RE: KY(WO4)(2), is a promising candidate for small, power-efficient, on-chip lasers and amplifiers. There are two major bottlenecks that complicate the realization of such devices. Firstly, the anisotropic thermal expansion coefficient of KY(WO4)(2) makes it challenging to integrate the crystal on glass substrates. Secondly, the crystal layer has to be, for example, < 1 mu m to obtain single mode, high refractive index contrast waveguides operating at 1550 nm. In this work, different adhesives and bonding techniques in combination with several types of glass substrates are investigated. An optimal bonding process will enable further processing towards the manufacturing of integrated active optical KY(WO4)(2) devices. (C) 2019 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

The cointegration of optical and microfluidic functions on chemically resilient borosilicate glass to provide microfluidic chemical analyses is described. An evanescent wave sensing chip containing a fluid channel of 21 mu L is implemented to carry out absorption spectroscopy measurements in the near-infrared range. Microchip packaging allows to perform remote analysis of harsh chemical solutions in confined environments. Detection of plutonium(VI) in aqueous 1 mol/L nitric acid solutions is achieved on solutions ranging from 0.05 to 0.13 mol/L. Results showcase the validity of the proposed approach by obtaining a sensor calibration curve and chip resilience to highly concentrated strong acids and radioactive elements. This proof-of-concept opens the path to optimized devices with a lower limit of detection. (C) 2019 Society of Photo-Optical Instrumentation Engineers (SPIE)