Toward Spectral-Domain Optical Coherence Tomography on a Chip

Akca, B. Imran; Nguyen, Van Duc; Kalkman, Jeroen; Ismail, Nur; Sengo, G.; Sun, Fangyuan; Driessen, A.; Leeuwen, Ton G. van; Pollnau, Markus; Wörhoff, Kerstin; Ridder, R.M. de

doi:10.1109/jstqe.2011.2171674

Cited by 54 publications

(45 citation statements)

References 31 publications

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“…It is attractive for use in optical wavelength-division-multiplexed networks but also for application to various other spectroscopic measurements, e.g. optical coherence tomography (OCT) [2] and Raman spectroscopy [3], or for confocal light delivery and collection [4]. There is a strong need for AWGs with low-loss and box-like passbands over a broad spectral range.…”

Section: Introductionmentioning

confidence: 99%

Broad-spectral-range synchronized flat-top arrayed-waveguide grating applied in a 225-channel cascaded spectrometer

Akca

Doerr²,

Sengo

et al. 2013

2013 Conference on Lasers &Amp; Electro-Optics Europe &Amp; International Quantum Electronics Conference CLEO EUROPE/IQEC

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We present a new synchronized design for flattening the passband of an arrayed-waveguide grating (AWG) over a broad wavelength range of 90 nm. A wavelength-insensitive 3-dB balanced coupler is designed to be used in duplicate in a Mach-Zehnder interferometer (MZI); the phase deviation created by one of the balanced couplers is cancelled by flipping the other coupler around. This MZI is arranged in tandem with the AWG such that the output signal of the MZI is the input signal of the AWG. We demonstrate a 5-channel, 18-nm-spacing AWG with a 0.5-dB bandwidth of 12 nm over a 90-nm spectral range. A low-loss cascaded AWG system is demonstrated by using the MZI-synchronized flat-top AWG as a primary filter.

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Section: Introductionmentioning

confidence: 99%

Broad-spectral-range synchronized flat-top arrayed-waveguide grating applied in a 225-channel cascaded spectrometer

Akca

Doerr²,

Sengo

et al. 2013

2013 Conference on Lasers &Amp; Electro-Optics Europe &Amp; International Quantum Electronics Conference CLEO EUROPE/IQEC

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“…This is to facilitate the reflection of incident light perpendicular to the surface of the Si wafer. Together with vertical sidewalls, 45° angled sidewalls can be used to reflect light to form complicated structures that facilitate interferometric imaging [2]. …”

Section: Introductionmentioning

confidence: 99%

Development of silicon optics for an integrated micro-optical system-on-a-chip

Kandasamy

Skafidas

2013

SPIE Proceedings

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Development of silicon-based passive optical components such as reflectors, waveguides, and beam splitters coupled with active elements such as light emitters and detectors enable miniaturisation of a low-cost system-on-a-chip sensing device. In this work, we investigate methods to fabricate passive silicon elements on a chip. We use a combination of wet and dry etching techniques to realise angled and vertical sidewalls normal to the surface of a silicon wafer, respectively. For wet etching, we used Triton-X, a surfactant, added to an alkaline solution TMAH as the etchant. This allows perfect 45° inclined sidewalls to be fabricated. Dry etching using DRIE is to be performed on the reverse-side of the same wafer to realize through-hole vias with straight vertical sidewalls. A final Au metal layer can then be coated onto the sidewalls to realize reflective surfaces. Photolithography masks used in the wet and dry etch processes were designed and fabricated. By careful alignment of these masks using a mask aligner, we can fabricate a combination of inclined and vertical sidewalls to build optical reflectors and beam splitters with complex geometries. When integrated with active Si-optical devices, a fully integrated micro-optical system-on-a-chip can be realised.

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“…High index contrast silicon-on-insulator platform has been chosen for planar waveguide devices working above 1 100 nm [3,4] , which is the absorption edge of silicon, whereas the silicon oxynitride (SiON) waveguide platform for wavelength range below 1 100 nm is favorable because of its variable refractive index (from 1.47 to 2.3) and broad highly transparent wavelength range (210 nm to 2 000 nm) [5] . SiON waveguide based AWG spectrometers have been recently reported, especially for Raman spectroscopy [6] and optical coherence tomography [7,8] . Compared with AWG, EDG is significantly smaller because a folded beam path is used.…”

mentioning

confidence: 99%

Echelle dif fraction grating based high-resolution spectrometer-on-chip on SiON waveguide platform

Ma¹,

He²,

Li³

2013

中国光学快报

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An echelle diffraction grating based high-resolution spectrometer-on-chip on silicon oxynitride (SiON) waveguide platform operated at a wavelength range of 850 nm is demonstrated. The chip comprises 120 output waveguides with 0.25-nm wavelength channel spacing and has a size of only 11 × 6 (mm). The experimental results show that the insertion loss is -14 dB, the measured adjacent channel crosstalk is less than -25 dB, the 3 dB channel bandwidth is < 0.1 nm, and the channel non-uniformity is 3 dB for 56 channels with a wavelength ranging from 838 to 852 nm.OCIS codes: 250.3140, 230.3120. doi: 10.3788/COL201311.032501.With the advancement of the wavelength-division multiplexing systems in optical communication in the past two decades, two types of planar waveguide based grating devices have been developed, namely, arrayed waveguide grating (AWG) and echelle diffraction grating (EDG). Recently, the application of AWG and EDG in the sensing area has received substantial interest because of their powerful ability in high-resolution spectral analysis with compact size, and potential for on-chip multi-functional integration [1,2] . High index contrast silicon-on-insulator platform has been chosen for planar waveguide devices working above 1 100 nm [3,4] , which is the absorption edge of silicon, whereas the silicon oxynitride (SiON) waveguide platform for wavelength range below 1 100 nm is favorable because of its variable refractive index (from 1.47 to 2.3) and broad highly transparent wavelength range (210 nm to 2 000 nm) [5] . SiON waveguide based AWG spectrometers have been recently reported, especially for Raman spectroscopy [6] and optical coherence tomography [7,8] . Compared with AWG, EDG is significantly smaller because a folded beam path is used. The current study presents a SiON waveguide based EDG spectrometer-on-chip operating in a wavelength range of 850 nm. Figure 1 shows the schematic of our EDG device. Through the input waveguide, light arrives at the boundary of the slab waveguide, diverges into the slab waveguide, illuminates the echelle grating facets, diffracts back, and then converges to the designated output waveguide according to its wavelength.The channel waveguide (1.25 µm wide and 1 µm high) was chosen as the core waveguide structure for the input and output waveguides. Single-mode operation around 850 nm is achieved with the refractive index of 1.52 for the SiON core layer and 1.46 for the SiO 2 buffer and upper cladding layers. The adjacent output waveguides are separated by a gap of 2.75 µm to minimize crosstalk. This gap corresponds to an output waveguide spacing of 4 µm, which is spread out to 32 µm via curved waveguides. Considering the wavelength channel spacing of 0.25 nm, a linear dispersion coefficient of 16 000 is obtained. The total number of output waveguides is 120, and the EDG was designed with a free spectral range of 28 nm at the 30th diffraction order. The number of grating teeth is 600, which is large enough to cover more than 99% of light energy emitted from the input w...

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Toward Spectral-Domain Optical Coherence Tomography on a Chip

Cited by 54 publications

References 31 publications

Broad-spectral-range synchronized flat-top arrayed-waveguide grating applied in a 225-channel cascaded spectrometer

Broad-spectral-range synchronized flat-top arrayed-waveguide grating applied in a 225-channel cascaded spectrometer

Development of silicon optics for an integrated micro-optical system-on-a-chip

Echelle dif fraction grating based high-resolution spectrometer-on-chip on SiON waveguide platform

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