Non-contact polishing of single crystal diamond by ion beam etching

We propose a non-contact surface finishing method for brittle substrates by ion beam etching and we experimentally demonstrate polishing of (100) single crystal diamond surface. We model and simulate the polishing process, and verify the results experimentally by monitoring individual defects during the surface treatment. Rapid flattening of scratches and digs, as typically present on brittle substrates after mechanical polishing, is observed: trench depth is typically removed by 95% in less than 30 min. The polishing method relies on physical bombardment of the substrate surface with accelerated inert gas ions, rendering it highly versatile and applicable to a wide variety of materials

Fabrication and Characterization of Freestanding Single Crystal Diamond and Silicon Microresonators

Microresonators are fundamental building blocks of any photonic integrated circuit, as they can be used as filters, modulators, sensors, and to enhance light emission. If these resonators are suspended and are free to oscillate, we can exploit the interaction of the optical and mechanical resonance. Demonstration of the fundamental interactions between the optical and mechanical fields, as well as applications based on this physics, were already presented for other material systems such as silicon, silicon oxide, or silicon nitride. Single crystal diamond is a strong candidate to realise high quality resonators due to the excellent material properties. The mechanical properties, such as stiffness, low intrinsic damping, and high thermal conductivity, are critical for mechanical oscillators with high frequency and high quality factor, which is strongly correlated to the noise of the oscillator. The wide transparency range and the low absorption enable operation in a large wavelength range spanning from near ultraviolet to far infrared. Diamond can host very bright emitters, based on defects of the diamond lattice, which can be employed as single photon sources, quantum memories, or very sensitive magnetic sensors. Chemical resistance to most acids or bases permit operations in aggressive environments. For these reasons, single crystal diamond is an attractive platform for integrated photonics and micro- or nanomechanics, and it should be possible to realize low noise optomechanical resonators. However, compared to more established material systems, microfabrication of single crystal diamond is not easy. High quality single crystal diamond substrates are available, to date, only as bulk plates, therefore it is important to develop fabrication strategies that isolate optically and mechanically a thin diamond layer from the rest of the diamond substrate. Over the last years, several approaches have been proposed and in this work two methods will be employed: 3D milling using a focused ion beam to create micrometer sized disks supported by a narrow pillar; and etching of the bulk diamond using a plasma which is selective to particular crystal planes of the single crystal diamond. Using these processes, single crystal diamond microresonators were realized, measuring optical quality factors of 5700 and 42000 at telecom wavelengths, respectively, and of 3100 and 10500 at visible wavelengths, respectively. Single crystal silicon is similar in many aspects to single crystal diamond, with the material properties being slightly worse. However, silicon benefits from decades of knowledge developed for integrated electronic circuits and integrated silicon photonics circuits. Silicon photonics is now extensively used in telecommunications to interface the optical links to electronics. Commercial foundries started to offer silicon photonics services, either within the CMOS fabrication or with dedicated processes. Micro Electro Mechanical Systems represent a way to expand on the capability of photonic integrated circuits by providing low power and/or reconfigurable components. In this context, optomechanical oscillators were realized by postprocessing an IMEC iSiPP50G silicon photonics chip. Optical quality factors of 300000 were measured at telecom wavelengths. Mechanical oscillations are supported at 250 MHz, with quality factors of 1800 measured at ambient conditions

Single crystalline diamond diffractive optical elements and method of fabricating the same

The present invention concerns a single crystalline diamond optical element production method. The method includes the steps of: ‐ providing a single crystalline diamond substrate or layer; ‐ applying a mask layer to the single crystalline diamond substrate or layer; ‐ forming at least one or a plurality of indentations or recesses through the mask layer to expose a portion or portions of the single crystalline diamond substrate or layer; and ‐ etching the exposed portion or portions of the single crystalline diamond substrate or layer

Method for flattening substrates or layers using 3d printing and etching

The present invention concerns a layer or substrate flattening method comprising the steps of: - providing a layer or substrate (1) to be flattened; - measuring a topography or surface profile of at least one area (3) of the layer or substrate to be flattened; - providing at least one etch layer (5A) on at least one area of the layer or substrate to be flattened; - defining a topography (7) of said at least one etch layer, said topography to be exposed to etching; and - etching the at least one etch layer comprising the defined topographic surface and the at least one area of the layer or substrate to provide a flattened surface on the at least one area of the layer or substrate

Enhancement of optical quality factor by thermal annealing of single crystal diamond micro-resonators

We report on the increase in optical quality factor of a suspended single crystal diamond micro-disk resonator by thermal annealing. The resonators are fabricated by Deep Reactive Ion Etching (DRIE) to obtain circular pillars in bulk single crystal diamond, followed by multidirectional Focused Ion Beam (FIB) milling to shape the anchor, thin the micro disk and smooth the sidewalls. Thermal annealing in air at 500 degrees C for 4 h eliminates FIB induced crystal damage yielding optical quality factors of up to 5'700, corresponding to an increase of up to 5x compared to the resonators before annealing

Single crystal diamond micro-disk resonators by focused ion beam milling

We report on single crystal diamond micro-disk resonators fabricated in bulk chemical vapor deposition diamond plates (3 mm × 3 mm × 0.15 mm) using a combination of deep reactive ion etching and Focused Ion Beam (FIB) milling. The resulting structures are micro-disks of few μm in diameter and less than 1 µm thick, supported by a square or diamond section pillar resulting from the multi-directional milling. Thin aluminum and chromium layers are used to ground the substrate, limit the ion implantation, and prevent edge rounding and roughening. FIB damage is then removed by a combination of hydrofluoric acid etching, oxygen plasma cleaning, and annealing at 500 °C for 4 h in air. We experimentally characterize the optical behavior of the devices by probing the transmission of a tapered fiber evanescently coupled to the micro-disk, revealing multiple resonances with a quality factor up to 5700 in the S- and C-band

Integrated photonic devices in single crystal diamond

The field of diamond photonics is reviewed, with a focus on recent experimental demonstrations of photonic integrated devices in a single crystal diamond. This field leverages the outstanding material properties of diamond with the aim to establish large-scale integrated photonics for applications in sensing, information and communication technologies, and optomechanics. Accordingly, this review introduces recent progress in scalable micro- and nano-fabrication techniques for single crystal diamond photonic integrated devices, and provides quantitative comparative evaluation of the performance of the state of the art devices. The review concludes with an outlook of the potential of photonic integrated circuits in single crystal diamond

Single crystalline diamond part production method for stand alone single crystalline mechanical and optical component production

The present invention relates to a free-standing single crystalline diamond part and a single crystalline diamond part production method. The method includes the steps of: - providing a single crystalline diamond substrate or layer; - providing a first adhesion layer on the substrate or layer; - providing a second adhesion layer on the first adhesion layer: - providing a mask layer on the second adhesion layer; - forming at least one indentation or a plurality of indentations through the mask layer and the first and second adhesion layers to expose a portion or portions of the single crystalline diamond substrate or layer; and - etching the exposed portion or portions of the single crystalline diamond substrate or layer and etching entirely through the single crystalline diamond substrate or layer

Silicon photonic MEMS variable optical attenuator

We present a design for an on-chip MEMS-actuated Variable Optical Attenuator (VOA) based on Silicon Photonic MEMS technology. The VOA consists of 30 individual mechanically movable MEMS cantilevers, suspended over an integrated, 1 mu m wide bus waveguide, each terminating with two optical attenuation bars. By exploiting the pull-in instability, electrostatic actuation allows to move the individual cantilevers into proximity of the waveguide, leading to scattering of the evanescent field and thus attenuation of the remaining optical power in the waveguide. Electrodes are placed below the cantilevers for electrostatic actuation. Mechanical stoppers are used to avoid contact between the cantilevers and the electrodes and to keep the bars at a precisely defined distance of 60 nm away from the bus waveguide. The attenuator provides nearly zero insertion loss in OFF state, while in ON state, the attenuation range is defined by the number of actuated digital attenuation cantilevers and can be adjusted in discrete increments of only 1.2 dB. Owing to the small size, fast microsecond scale response time can be achieved, and electrostatic MEMS actuation allows for broadband and low-power operation. Our design exhibits a compact footprint of 30 mu m x 45 mu m, attenuation from 0 dB to 36 dB, while keeping return loss below 27 dB. To the best of our knowledge, this is the first presentation of a design of a VOA in Silicon Photonic MEMS technology

Die Level Release of Silicon Photonic MEMS

We demonstrate a die level release process for silicon photonic MEMS structures, that is compatible with dies from a standard silicon photonics foundry process which are only several square millimeters in size