This PDF file contains the front matter associated with SPIE Proceedings Volume 10249, including the Title Page, Copyright information, Table of Contents, Introduction (if any), and Conference Committee listing.

In this paper, the fabrication method of waveguide structures and devices as ring resonators for different waveguide applications based on polymer material is presented. The structures were designed in computer-aided design (CAD) software and two-photon polymerization lithography system was used for preparation of desired devices. Morphological properties of prepared devices were investigated using scanning electron microscope (SEM) and confocal microscope. Finally, we performed measurement of optical spectrum characteristics in telecommunication wavelengths range. The results corresponds to calculated parameters. Final polymer devices are promising for lab on a chip and sensing applications due to unique elastic and chemical properties.

Silicon sub-wavelength structures have found widespread applications in devices ranging from fiber-to-chip couplers to spectrometers. So far, these structures have been mainly used to engineer the local refractive index. Here we focus on two further applications. We describe how to engineer the waveguide electromagnetic field distribution for enhanced evanescent field sensing, predicting a 6-fold enhancement of the sensitivity compared to conventional waveguides. We furthermore report experimental results on broadband multimode interference couplers, which, by leveraging the inherent anisotropy of the sub-wavelength structures, achieve virtually perfect operation over a bandwidth of more than 300nm at telecom wavelengths.

Silicon photonic is becoming a reality for next generation communication system addressing the increasing needs of HPC (High Performance Computing) systems and datacenters. CMOS compatible photonic platforms are developed in many foundries integrating passive and active devices. The use of existing and qualified microelectronics process guarantees cost efficient and mature photonic technologies. Meanwhile, photonic devices have their own fabrication constraints, not similar to those of cmos devices, which can affect their performances.

In this paper, we are addressing the integration of PN junction Mach Zehnder modulator in a 200mm CMOS compatible photonic platform. Implantation based device characteristics are impacted by many process variations among which screening layer thickness, dopant diffusion, implantation mask overlay. CMOS devices are generally quite robust with respect to these processes thanks to dedicated design rules. For photonic devices, the situation is different since, most of the time, doped areas must be carefully located within waveguides and CMOS solutions like self-alignment to the gate cannot be applied. In this work, we present different robust integration solutions for junction-based modulators. A simulation setup has been built in order to optimize of the process conditions. It consist in a Mathlab interface coupling process and device electro-optic simulators in order to run many iterations. Illustrations of modulator characteristic variations with process parameters are done using this simulation setup. Parameters under study are, for instance, X and Y direction lithography shifts, screening oxide and slab thicknesses. A robust process and design approach leading to a pn junction Mach Zehnder modulator insensitive to lithography misalignment is then proposed. Simulation results are compared with experimental datas. Indeed, various modulators have been fabricated with different process conditions and integration schemes. Extensive electro-optic characterization of these components will be presented.

With the increasing demand of data, current chip-scale communication systems based on metallic interconnects suffer rate limitations and power consumptions. In this context, Silicon photonics has emerged as an alternative by replacing the classical copper interconnects with silicon waveguides while taking advantage of the well-established CMOS foundries techniques to reduce fabrication costs. Silicon is now considered as an excellent candidate for the development of integrated optical functionalities including waveguiding structures, modulators, switches… One of the main challenges of silicon photonics is to reduce the power consumption and the swing voltage of optical silicon modulators while increasing the data rate speed. However, silicon is a centrosymmetric crystal, vanishing the second order nonlinear effect i.e. Pockels effect which is intrinsically a high speed effect. To overcome this limitation, mechanical stresses on silicon to break the crystal symmetry can be used depositing a strained overlayer.

In this work, we have studied the effect of the stress layer in the modulation characteristics based on Mach-Zehnder interferometers. The deposition of silicon nitride as the stress layer and its optimization to induce the maximum effect will be presented.

The large transparency window of silicon (1.1 - 8 μm wavelength range) makes it a promising material for the implementation of on-chip sensors operating over an ultra-wide wavelength range. However, the implementation of the silicon-on-insulator platform is restricted by the absorption of buried oxide layer for wavelengths above 4 μm. Here, we report our advances in development of silicon waveguides for broadband operation extending from near- to mid-infrared wavelengths. We present suspended silicon waveguides that exploit a novel periodic corrugation approach to circumvent the buried oxide absorption problem and provide effective single mode operation simultaneously for near- and mid-infrared wavelengths.

In this work we present a design to enhance absorption of infrared light by a fluid analyte being in contact with a slot photonic crystal ring resonator (slot-PCRR). For this purpose, we propose a new PCRR design facilitating higher interaction between guided mode and analyte. These types of PCRRs are based on two-dimensional photonic crystals, which consist of an array of holes in a silicon slab being arranged in a hexagonal lattice. The holes will be filled with liquid analyte. A slot is embedded in this hexagonal ring cavity to create a slot-PCRR. The strong confinement of light in the low index region, occupied by the analyte, is the key advantage of the slot- PCRR. We also calculate the relative intensity change in the transmission spectrum due to the absorption in the analyte. The maximum change obtained is given by a mode which has most of the electromagnetic field energy in the region the region filled with the analyte. Furthermore, this mode is well separated from neighboring bands, which has the advantage that impinging light with specified frequency is less likely to spuriously couple to other modes with the same frequency, which would decrease the amount of energy coupled to desired mode. The slot-PCRR yields a higher relative change due to absorption compared to the PCRR without a slot. In this work, the radii of six rods at the outer PhC were tuned to enhance the quality factor of slot-PCRR. Using these optimum values of radii, the Q-factor rises up to 80000.

In this paper we demonstrate design and fabrication of two- (2D) and three-dimensional (3D) ring resonators prepared by 3D laser lithography based on two photon polymerization. We used dip-in direct-laser-writing (DLW) optical lithography to fabricate 3D optical structures for optics and optoelectronics. Prepared structures are embedded in polydimethylsiloxane, which is well known silicon elastomer with unique mechanical and optical properties. This polymer structure allows to couple light directly from single mode optical fiber to the ring resonator structure, where polydimethylsiloxane creates cladding. Optical properties of prepared 2D and 3D ring resonators were investigated by measurement of transmission spectral characteristics.

Since it’s first generation more than 30 years ago, squeezed light has developed towards a tool for high precision measurements as well as a tool for quantum information tasks like quantum key distribution. Miniaturization of sensors is an active field of research with the prospect of many applications. The precision of optical sensors based on interferometric measurements is often limited by the fundamental shot noise. While shot noise can be reduced by increasing the employed light power, integrated sensors pose limitations on the maximum possible amount due to damaging effects of high intensity as well as power consumption. Bright quadrature squeezed light produced by the optical Kerr effect in a nonlinear medium offers an opportunity to overcome these limitations. Here, we present first steps towards a bright quadrature squeezed light source produced by the optical Kerr effect in race-track resonators in silicon nitride by presenting characterizations of the chip. Using standard fabrication techniques this source will have the potential of seamless integration into on-chip optical sensors.

A novel approach for tracking of whispering gallery modes (WGM) in real-time for dielectric cavities used in sensing application is presented in this paper. Real-time tracking for the shifts of the WGM can be used to measure the physical quantity of interest precisely, under high repetition rates. The tracking algorithm is based on cross-correlation signal processing technique which has been proved to be accurate in WGM shifts detection. In order to achieve portability, the aforementioned real-time algorithm is implemented using a single-board re-configurable input-output hardware. The hardware platform used combines a real-time processor and a field programmable gate array (FPGA), it also allows for data exchange between them. The tracking algorithm’s accuracy and real-time behavior is verified by preforming simulations based on experiments conducted on the dielectric cavity, where the cavity is used as a force sensor measuring mechanical compression. The light from a laser diode is tuned with rates up to 10 kHz and then tangentially coupled into the cavity to excite the WGM. Results show that shifts of the WGM are tracked by the algorithm providing real-time force readings.

Advanced technologies to implement on-chip monitoring and feedback control operations are required to make silicon photonics scale to large-scale-of-integration. Transparent detectors and energy saving actuators are key ingredients of this paradigm. On-chip detectors are required to be minimally invasive in order to allow their integration in key spots of the circuit, thus easing control operation through the partitioning of complex architectures in smaller cluster of devices and the realization of local feedback control loops. Non volatile integrated actuators, which are reversible switching devices that can maintain the state without the need of “always on” power dissipation, are also needed to reduce the power consumption required by tuning, reconfiguration and stabilization operations. Addressing these issues, in this contribution we report on the performance of a recently developed transparent detector, named ContacLess Integrated Photonic Probe (CLIPP), that can monitor in line the intensity of the light in silicon waveguides without introducing any photon absorption in excess to the waveguide propagation loss. A systematic characterization of the CLIPP detector is here presented, specifically addressing the dependence of the CLIPP performance on the waveguide geometry and on the polarization and wavelength of the light. Concerning the development of non-volatile integrated actuators, we demonstrate the possibility to manipulate the light transmission in silicon waveguides by electrochemical insertion of mobile ions in a mixed ionic and electronic conductor (MIEC) used as upper cladding of a silicon waveguide. A finely controllable and reversible change of the imaginary part of the refractive index of the MIEC film is exploited to trim the loss of a silicon waveguide and to modify the frequency response of a silicon microring resonator.

Infrared (IR) spectroscopy is widely recognized as a gold standard technique for chemical analysis. Traditional IR spectroscopy relies on fragile bench-top instruments located in dedicated laboratory settings, and is thus not suitable for emerging field-deployed applications such as in-line industrial process control, environmental monitoring, and point-ofcare diagnosis. Recent strides in photonic integration technologies provide a promising route towards enabling miniaturized, rugged platforms for IR spectroscopic analysis. Chalcogenide glasses, the amorphous compounds containing S, Se or Te, have stand out as a promising material for infrared photonic integration given their broadband infrared transparency and compatibility with silicon photonic integration. In this paper, we discuss our recent work exploring integrated chalcogenide glass based photonic devices for IR spectroscopic chemical analysis, including on-chip cavityenhanced chemical sensing and monolithic integration of mid-IR waveguides with photodetectors.

We evaluate a recently devised design of vertical-cavity enhanced resonant thermal emitter (VERTE) regarding stability to fabrication tolerances of PVD layer deposition techniques. Such an emitter achieves narrowband and coherent thermal emission and is composed of an multilayer stack of dielectric layers (silicon and silica) on top of a reflective metal (silver) structure. The silica layer above the metal acts as a vertical cavity enhancing the electromagnetic field between the reflective metal and the dielectric stack forming a Bragg mirror (1-D photonic crystal). In our previous work, we identified several suitable five-layer-stack configurations, which considered several features and limitations of a real-world device, such as temperature dependence of the materials, fabrication constraints or unwanted emission modes. However, the emission characteristics are very sensitive to the geometrical and optical properties of the material. In order to examine this behaviour, a Monte-Carlo algorithm was used to apply a Gauss-distributed error in depth (relative the unperturbed layer thickness) for every individual layer. The robustness of the emission properties against fabrication errors were evaluated and analyzed by significant statistical quantities. As expected, the main issue compromising the emission properties is a deviation of the resonance wavelength in relation to the initial target resonance wavelength of the unperturbed configuration. Interestingly, configurations with larger average layer thicknesses and therefore with larger absolute thickness deviations did not exhibit a larger variance of the emission wavelength. Instead, the variance slightly decreased or remained constant. A similar result was obtained for increasing the number of dielectric layers. In contrast, the peak emissivity (at normal incidence) was significantly influenced by the average layer depth of a configuration. Also, the effect of broadening of the spectral emittance curve due to random thickness fluctuations was evaluated. It was found that the broadening due to relative thickness errors can be considered as negligible for most configurations.

Commercial photodiodes suffer from reflection losses and different recombination losses that reduce the collection efficiency. Recently, we realized a near-ideal silicon photodiode that exhibits an external quantum efficiency above 95% over the wavelength range of 235 – 980 nm, exceeds 100% below 300nm, and provides a very high response at incident angles of up to 70 degrees. The high quantum efficiency is reached by 1) virtually eliminating front surface reflectance by forming a “black silicon” nanostructured surface having dimensions proportional to the wavelength of light to be detected and 2) using an induced junction for signal collection instead of a conventional doped p-n junction, virtually eliminating Auger recombination at the light entry surface. This recombination prevention is especially important in ultraviolet detection since ultraviolet photons are absorbed very close to device surface, where conventional photodiodes have high doping concentration causing loss of signal, but induced junction diode is able to collect virtually all charge carriers generated. In this paper, we analyse the performance of our photodiodes under ultraviolet radiation.

Resonator-Quantum Well Infrared Photo detectors (R-QWIPs) are the next generation of QWIP detectors that use resonances to increase the quantum efficiency (QE). Recently, we are exploring R-QWIPs for broadband long wavelength applications. To achieve the expected performance, two optimized inductively coupled plasma (ICP) etching processes (selective and non-selective) are developed. Our selective ICP etching process has a nearly infinite selectivity of etching GaAs over Ga_1-xAl_xAs. By using the etching processes, two format (1Kx1K and 40x40) detectors with 25 μm pixel pitch were fabricated successfully. In despite of a moderate doping of 0.5 × 1018 cm^-3 and a thin active layer thickness of 0.6 or 1.3 μm, we achieved a quantum efficiency 35% and 37% for 8 quantum wells and 19 quantum wells respectively. The temperature at which photocurrent equals dark current is about 66 K under F/2 optics for a cutoff wavelength up to 11 μm. The NEΔT of the FPAs is estimated to be 22 mK at 2 ms integration time and 60 K operating temperature. This good result thus exemplifies the advantages of R-QWIP.

This work presents a new continuous-time equalization approach to overcome the limited bandwidth of integrated CMOS photodetectors. It is based on a split-path topology that features completely decoupled controls for boosting and gain; this capability allows a better tuning of the equalizer in comparison with other architectures based on the degenerated differential pair, which is particularly helpful to achieve a proper calibration of the system. The equalizer is intended to enhance the bandwidth of CMOS standard n-well/p-bulk differential photodiodes (DPDs), which falls below 10MHz representing a bottleneck in fully integrated optoelectronic interfaces to fulfill the low-cost requirements of modern smart sensors. The proposed equalizer has been simulated in a 65nm CMOS process and biased with a single supply voltage of 1V, where the bandwidth of the DPD has been increased up to 3 GHz.

The article presents field oriented control method of synchronous permanent magnet motor equipped in optical sensors. This method allows for a wide range regulation of torque and rotational speed of the electric motor. The paper presents mathematical model of electric motor and vector control method. Optical sensors have shorter time response as compared to the inductive sensors, which allow for faster response of the electronic control system to changes of motor loads. The motor driver is based on the digital signal processor which performs advanced mathematical operations in real time. The appliance of Clark and Park transformation in the software defines the angle of rotor position. The presented solution provides smooth adjustment of the rotational speed in the first operating zone and reduces the dead zone of the torque in the second and third operating zones.

The infrared wire-grid polarizer consisting of an Al grating, Si, and sol-gel derived zirconia grating film was fabricated by soft imprint process and Al shadow coating processes. A silicone mold was used because of its low surface energy, flexibility, and capability of transferring submicrosized patterns. As a result, the Al grating with a pitch of 400 nm and a depth of 100 nm was obtained on the zirconia grating film. The fabricated polarizer exhibited a polarization function with the TM transmittance greater than that of the Si substrate in the specific wavelength range of 3.6–8.5 μm, because the zirconia film acted as an antireflection film. The maximum value was 63% at a wavelength of 5.2 μm. This increment of the TM transmission spectrum results in interference within the zirconia film. Also, the extinction ratio exceeded almost 20 dB in the 3-8.8 μm wavelength range.

Diffusion doped p-i-n/p-n diodes in SOI substrate is proposed for the fabrication of active silicon photonics devices with scalable waveguide cross-sections. The p-type and n-type diffusion doping parameters are optimized for the fabrication of tunable single-mode waveguide phase-shifters with microns to submicron cross-sectional dimensions. The simulations results show that the shape of depletion layer can be effectively engineered by suitably positioning the rib waveguide with respect to the gap between doping windows. We could thus introduce an additional control parameter to optimize over-all figure of merits of the phase-shifter for various applications. For an optimized set of diffusion parameters, the V_πL_π of single-mode waveguides designed with 1μm, 0.5μm, and 0.25μm device layers (under reverse bias operating in TE-polarization at λ ~ 1550 nm) are found as 2.7 V-cm, 2.1 V-cm, and 1.6 V-cm, respectively. The typical p-n junction capacitance of an optimized 0.25μm single-mode waveguide is estimated to be < 0.5 fF/μm, which is comparable to that of ion-implanted p-n waveguide junctions.

A Fast Steering Mirror (FSM) of large diameter has been designed, built and tested. In order to make continuous tracking ability without loss of a target image, the FSM should be equipped with a large scale mirror for a wide field of view and require a high control bandwidth to reduce the tracking error. The design intricacies and trade-offs among various parameters of the FSM of large diameter to meet the desired goals are discussed. Finally, this device steers the large aperture mirror about two axes, achieving the operating range of 1mradian and a small-signal closed-loop bandwidth up to 500Hz which is greater than the structural resonance.

Progress in nanotechnologies accelerated the polymer based photonics, where simple and cheap solutions often bring comparable and sometimes also novel interesting results. Good candidates are polymer photoresists and siloxane materials with unique mechanical and optical properties. We present laser lithography as efficient tool for fabrication of different three-dimensional (3D) structures embedded in polydimethylsiloxane (PDMS) membranes. Presented concept of PDMS based thin membranes with 3D structures works as an effective diffraction element for modification of radiation pattern diagram of light emitting diodes and changes also the angular photoresponse of photodiodes. All these results were demonstrated on two types of 3D structures – spheres arranged in cubic lattice and woodpile structure.

In this contribution, we present modification of far field of light emitting diode (LED) with implemented Fresnel structure in the LED surface. Fresnel structures were prepared in one-dimensional arrangement with two different foci f₁ = 12.5 μm and f₂ = 1 cm. Structures were etched directly in the LED emitting surface using electron beam lithography with the etched depth for the structure with f₁ and f₂ app. 200 nm and 400 nm, respectively. Due to application of these structures, LED far field narrowing was observed, which is documented by goniophotometer measurements. For the structure with f₁ and f₂, the intensity decrease for angles ±30° – ±50° is app. 3-4% and 5-6%, respectively, in comparison to the Lambertian profile.

In this paper, we demonstrate a regrowth-free monolithically integrated photonics circuit which consists of a tunable, single-frequency, low-linewidth 1x2 multimode-interferometer laser diode (MMILD) and two waveguide devices connected with the two arms of the laser and electrically isolated by deep etched slots. In this photonic integrated circuit (PIC), the 1x2 MMILD showed similar tuning and single frequency performance as the discrete 1x2 MMILD, with more than 30dB side mode suppression ratio (SMSR). The integrated waveguide devices could be used as semiconductor optical amplifiers, photodiodes or electro-absorption modulators, thus the integrated circuit could be used for different functions. The integrability of the MMI lasers indicates its potential applicability in more advanced low-cost topological PICs.