Showing papers by "Kerstin Worhoff published in 2010"
TL;DR: Erbium-doped aluminum oxide integrated optical amplifiers were fabricated on silicon substrates, and their characteristics were investigated for Er concentrations ranging from 0.27 to 4.2×1020 cm−3.
Abstract: Erbium-doped aluminum oxide integrated optical amplifiers were fabricated on silicon substrates, and their characteristics were investigated for Er concentrations ranging from 0.27 to 4.2×1020 cm−3. Background losses below 0.3 dB/cm at 1320 nm were measured. For optimum Er concentrations in the range of 1 to 2×1020 cm−3, an internal net gain was obtained over a wavelength range of 80 nm(1500-1580 nm), and a peak gain of 2.0 dB/cm was measured at 1533 nm. The broadband and high peak gain are attributed to an optimized fabrication process, improved waveguide design, and pumping at 977 nm as opposed to 1480 nm. In a 5.4-cm-long amplifier, a total internal net gain of up to 9.3 dB was measured. By use of a rate-equation model, an internal net gain of 33 dB at the 1533 nm gain peak and more than 20 dB for all wavelengths within the telecom C-band (1525-1565 nm) are predicted for a launched signal power of 1 μW when launching 100 mW of pump power into a 24-cm-long amplifier. The high optical gain demonstrates that Al2O3:Er3+ is a competitive technology for active integrated optics.
137 citations
TL;DR: This work reports the realization and performance of a distributed feedback channel waveguide laser in erbium-doped aluminum oxide on a standard thermally oxidized silicon substrate and the diode-pumped continuous-wave laser, which demonstrated a threshold of 2.2 mW absorbed pump power and a maximum output power of more than 3 mW.
Abstract: We report the realization and performance of a distributed feedback channel waveguide laser in erbium-doped aluminum oxide on a standard thermally oxidized silicon substrate. The diode-pumped continuous-wave laser demonstrated a threshold of 2.2 mW absorbed pump power and a maximum output power of more than 3 mW with a slope efficiency of 41.3% versus absorbed pump power. Single-longitudinal-mode and single-polarization operation was achieved with an emission linewidth of 1.70+-0.58 kHz (corresponding to a Q factor of 1.14 × 10e11), which was centered at a wavelength of 1545.2 nm.
136 citations
TL;DR: The straightforward wafer-scale fabrication process, which includes reactive co-sputtering and subsequent reactive ion etching, allows for parallel integration of multiple amplifier and laser sections with silicon or other photonic circuits on a chip.
Abstract: Monolithic integration of Al2O3:Er3+ amplifier technology with passive silicon-on-insulator waveguides is demonstrated. A signal enhancement of >7 dB at 1533 nm wavelength is obtained. The straightforward wafer-scale fabrication process, which includes reactive co-sputtering and subsequent reactive ion etching, allows for parallel integration of multiple amplifier and laser sections with silicon or other photonic circuits on a chip.
94 citations
TL;DR: Integrated Al(2)O(3):Er(3+) channel waveguide ring lasers were realized on thermally oxidized silicon substrates and wavelength selection in the range 1530-1557 nm was demonstrated by varying the length of the output coupler from the ring.
Abstract: Integrated $Al_2O_3:Er^{3+}$ channel waveguide ring lasers were realized on thermally oxidized silicon substrates. High pump power coupling into and low laser output power coupling from the ring is achieved in a straightforward
design. Output powers of up to 9.5 $\mu $W and slope efficiencies of up to 0.11% were measured while lasing was observed for a threshold diode-pump power as low as 6.4 mW for ring lasers with cavity lengths varying from 2.0 to 5.5 cm. Wavelength selection in the range 1530–1557 nm was demonstrated by varying the length of the output coupler from the ring.
75 citations
TL;DR: Channel waveguide laser operation was achieved with a launched pump power threshold of only 5 mW, a slope efficiency of 62% versus launch pump power, and 76 mW output power.
Abstract: Epitaxially grown, 2.4-μm-thin layers of KY(WO4)2:Gd3+, Lu3+, Yb3+, which exhibit a high refractive index contrast with respect to the undoped KY(WO4)2 substrate, have been microstructured by Ar beam milling, providing 1.4-μm-deep ridge channel waveguides of 2 to 7 μm width, and overgrown by an undoped KY(WO4)2 layer. Channel waveguide laser operation was achieved with a launched pump power threshold of only 5 mW, a slope efficiency of 62% versus launched pump power, and 76 mW output power.
68 citations
TL;DR: In KGd(1-x)Lu(x)(WO(4))(2):Yb(3+) channel waveguides grown onto KY(WO (4) substrates by liquid phase epitaxy and microstructured by Ar+ beam etching, it is shown that continuous-wave output power at 1023 nm with a slope efficiency of 71% and a threshold of 40 mW of launched pump power at 981 nm is produced.
Abstract: In KGd1-xLux(WO4)2:Yb3+ channel waveguides grown onto KY(WO4)2 substrates by liquid phase epitaxy and microstructured by Ar+ beam etching, we produced 418 mW of continuous-wave output power at 1023 nm with a slope efficiency of 71% and a threshold of 40 mW of launched pump power at 981 nm. The degree of output coupling was 70%. By grating tuning in an extended cavity and pumping at 930 nm, we demonstrated laser operation from 980 nm to 1045 nm. When pumping at 973 nm, lasing at 980 nm with a record-low quantum defect of 0.7% was achieved.
62 citations
TL;DR: In this paper, the Nd3+ ions with a lifetime of 325 μs were used to generate photoluminescence at 880, 1060, and 1330 nm.
Abstract: Neodymium-doped aluminum oxide films with a range of Nd3+ concentrations are deposited on silicon wafers by reactive co-sputtering, and single-mode channel waveguides with various lengths are fabricated by reactive ion etching. Photoluminescence at 880, 1060, and 1330 nm from the Nd3+ ions with a lifetime of 325 μs is observed. Internal net gain at 845–945 nm, 1064, and 1330 nm is experimentally and theoretically investigated under continuous-wave excitation at 802 nm. Net optical gain of 6.3 dB/cm at 1064 nm and 1.93 dB/cm at 1330 nm is obtained in a 1.4-cm-long waveguide with a Nd3+ concentration of 1.68 × 1020 cm−3 when launching 45 mW of pump power. In longer waveguides a maximum gain of 14.4 dB and 5.1 dB is obtained at these wavelengths, respectively. Net optical gain is also observed in the range 865–930 nm and a peak gain of 1.57 dB/cm in a short and 3.0 dB in a 4.1-cm-long waveguide is obtained at 880 nm with a Nd3+ concentration of 0.65 × 1020 cm−3. By use of a rate-equation model, the gain on these three transitions is calculated, and the macroscopic parameter of energy-transfer upconversion as a function of Nd3+ concentration is derived. The high internal net gain indicates that Al2O3:Nd3+ channel waveguide amplifiers are suitable for providing gain in many integrated optical devices.
51 citations
TL;DR: In this article, laser operation was achieved in microstructured channel waveguides of WO4)2:Gd3+, Lu3+, Yb3+, resulting in a threshold of only 5 mW, a slope efficiency of 62% versus launched pump power, and 76 mW output power.
Abstract: Laser operation was achieved in microstructured channel waveguides of KY(WO4)2:Gd3+, Lu3+, Yb3+, resulting in a threshold of only 5 mW, a slope efficiency of 62% versus launched pump power, and 76 mW output power.
15 citations
16 May 2010
TL;DR: In this paper, an integrated low-loss arrayed waveguide grating is designed for Raman spectroscopy of the human skin, which targets spectral analysis of Raman-scattered light for in vivo determination of water concentration in the stratum corneum.
Abstract: An integrated low-loss arrayed waveguide grating is designed for Raman spectroscopy of the human skin. The device layout targets spectral analysis of Raman-scattered light for in vivo determination of water concentration in the stratum corneum.
6 citations
06 Apr 2010
TL;DR: In this article, the results of an optimization study of deeply-etched Bragg gratings in WO4.2:Yb3+ to obtain photonic cavity structures are reported.
Abstract: Results of an optimization study of deeply-etched Bragg gratings in KY(WO4)2:Yb3+ to obtain photonic cavity structures are reported. By optimizing parameters such as dose per area, dwell time and pixel resolution the redeposition effects are minimized and 4.3um-deep gratings are achieved.
3 citations
16 May 2010
TL;DR: In this paper, integrated Al 2 O 3 :Er3+ ring laser was realized on thermally oxidized silicon substrates by varying the degree of output coupling from the ring, wavelength selection in the range 1530-1557 nm was demonstrated.
Abstract: Integrated Al 2 O 3 :Er3+ ring lasers were realized on thermally oxidized silicon substrates. By varying the degree of output coupling from the ring, wavelength selection in the range 1530–1557 nm was demonstrated.
16 May 2010
TL;DR: In this article, a silicon oxynitride based arrayed waveguide grating spectrometer was designed for on-chip spectral-domain optical coherence tomography systems, which is shown to be promising for miniaturizing the current OCT systems through integrated optics.
Abstract: A silicon oxynitride based arrayed waveguide grating spectrometer was designed for on-chip spectral-domain optical coherence tomography systems. Transmission measurement results are promising for miniaturizing the current optical coherence tomography systems through integrated optics.
16 May 2010
TL;DR: In this article, a single-frequency distributed feedback lasing with 165 µW output power at 1538.8 nm is realized in Al 2 O 3 ∶Er3+ waveguides fabricated on silicon wafers.
Abstract: Single-frequency distributed-feedback lasing with 165 µW output power at 1538.8 nm is realized in Al 2 O 3 ∶Er3+ waveguides fabricated on silicon wafers. Distributed feedback is provided by a surface relief Bragg grating fabricated with laser interference lithography.
21 Jun 2010
TL;DR: Distributed phase-shift holographically-written surface relief Bragg gratings have been integrated with Al2O3 waveguides via reactive ion etching of SiO2 overlay films and demonstrate Q-values as high as 125000.
Abstract: Distributed phase-shift holographically-written surface relief Bragg gratings have been
integrated with Al2O3 waveguides via reactive ion etching of SiO2 overlay films. The realized
optical cavities are highly reflective and demonstrate Q-values as high as 125000.
01 Jan 2010
TL;DR: In this article, a distributed feedback channel waveguide laser in erbium-doped aluminum oxide on a silicon substrate is reported, which has a threshold pump power of 15 mW and emits 3 mW in single-frequency operation at 1545.2 nm wavelength with a slope efficiency of 6.2% and linewidth of 15 kHz.
Abstract: A distributed feedback channel waveguide laser in erbium-doped aluminum oxide on a silicon substrate is reported. The optically pumped laser has a threshold pump power of 15 mW and emits 3 mW in single-frequency operation at 1545.2 nm wavelength with a slope efficiency of 6.2% and linewidth of 15 kHz.
01 Jan 2010
TL;DR: In this paper, the optical fields at the output of the elliptic coupler are simulated and measured, and good agreement is observed between the measured OCT signal as a function of depth and calculations based on the optical field at the end of the coupler.
Abstract: Integrated optics potentially can offer significant cost reductions and new applications to Optical Coherence Tomography (OCT). We design, fabricate, and characterize Silicon oxynitride (SiON) elliptic couplers, which can be used to focus light from a chip into the off-chip environment. Fizeau-based OCT measurements are performed with elliptic couplers and a moveable mirror. The optical fields at the output of the elliptic coupler are simulated and measured. Good agreement is observed between the measured OCT signal as a function of depth and calculations based on the optical field at the end of the elliptic coupler.
07 Jun 2010
TL;DR: In this paper, the authors demonstrated 170 Gbit/s data amplification at 1.5 μm in Al2O3:Er3+ with an 800-nm laser diode with small-signal gain at 880 nm, 1064 nm and 1330 nm of 1.57 dB, 6.30 dB/cm and 1.93 dB, respectively, for individually optimized Nd3+ concentrations.
Abstract: Amorphous aluminium oxide is an excellent host material for rareearth ions. Its low loss and large refractive index allow for the realization of compact integrated optical devices. Recently, we demonstrated 170 Gbit/s data amplification at 1.5 μm in Al2O3:Er3+. Here Al2O3 is used as the host material for Nd3+. The layers are reactively co-sputtered onto thermally oxidized 10-cm Si wafers, thus enabling compatibility with standard silicon technology. Single-mode channel waveguides with 600-nm thickness and various widths are fabricated. Under pumping with an 800-nm laser diode, small-signal gain at 880 nm, 1064 nm and 1330 nm of 1.57 dB/cm, 6.30 dB/cm and 1.93 dB/cm, respectively, is demonstrated for individually optimized Nd3+ concentrations. A maximum gain of 3.0 dB, 14.4 dB and 5.1
dB, respectively, is measured. Energy-transfer upconversion of Nd3+ ions in Al2O3 is studied as a loss mechanism. Furthermore, use of the amplifiers in polymer optical backplanes embedded within printed circuit boards is
investigated. Pump light at 800 nm and signal light at 880 nm were directly coupled from a polymer waveguide into 3 μm-thick Al2O3:Nd3+ waveguides, with the width tapered down from 8 μm to 1.5-2.5 μm to increase the pump intensity. Internal net gain of 0.42 dB was demonstrated for an amplifier coupled to a polymer optical backplane, providing a potential solution for compensating loss and achieving loss-less data transmission in optical interconnects.
16 May 2010
TL;DR: In this paper, an integrated erbium-doped waveguide amplifier was used to achieve 170 Gbit/s transmission at 1550 nm with open eye diagrams and no power penalty was observed.
Abstract: Transmission of a 170 Gbit/s signal at 1550 nm was demonstrated in an integrated erbium-doped waveguide amplifier. Open eye diagrams and no power penalty were observed with the amplifier in the transmission system.
01 Jan 2010
TL;DR: In this paper, a silicon oxynitride-based arrayed waveguide grating (AWG) spectrometers were designed for on-chip spectral-domain optical coherence tomography (OCT) systems and Raman spectroscopy of the skin.
Abstract: Silicon oxynitride-based arrayed waveguide grating (AWG) spectrometers were designed for on-chip spectral-domain optical coherence tomography (OCT) systems and Raman spectroscopy of the skin. A novel geometrical layout for Raman spectroscopy was introduced to reduce loss. Measurements show that integrated optics has a good potential for miniaturizing current OCT systems.
07 Apr 2010
TL;DR: In this paper, 21 evanescently coupled waveguides are fabricated to implement quantum random walks and a generalised form of two-photon non-classical interference, which observed via two photon correlation.
Abstract: Arrays of 21 evanescently coupled waveguides are fabricated to implement quantum random walks and a generalised form of two-photon non-classical interference, which observed via two photon correlation.
01 Sep 2010
TL;DR: In this paper, lattice-matched KY(WO4)2:Gd3+,Lu3+,Tm3+ layers with a thickness of 6 μm have been grown onto pure KY (WO 4)2 substrates.
Abstract: Lattice-matched KY(WO4)2:Gd3+,Lu3+,Tm3+ layers with a thickness of 6 μm have been grown onto pure KY(WO4)2 substrates. Channel waveguides of 7.5 μm to 12.5 μm width have been microstructured to a depth of 1.5 μm using Ar+ beam milling. Laser experiments with buttcoupled mirrors demonstrate laser oscillation near 1844 nm while pumping at 792 nm.
TL;DR: In this paper, the authors have presented an analysis of the performance of microring and distributed-feedback laser in Al2O3:Er waveguides on silicon, as well as amplifiers and continuous-wave laser in Nd-doped polymer waveguide on silicon.
Abstract: 170 Gbit/s data transmission, microring lasers operating across the telecom C-band, and narrow-linewidth distributed-feedback lasers in Al2O3:Er waveguides on silicon, as well as amplifiers and continuous-wave lasers in Nd-doped polymer waveguides on silicon are presented.
16 May 2010
TL;DR: Al 2 O 3 :Nd3 + channel waveguide amplifiers with various lengths and Nd3+ concentrations were fabricated in this article, and a maximum 3 dB gain at 880 nm was obtained.
Abstract: Al 2 O 3 :Nd3+ channel waveguide amplifiers with various lengths and Nd3+ concentrations were fabricated. Internal net gain at 845–940 nm was investigated and a maximum 3 dB gain at 880 nm was obtained.
16 May 2010
TL;DR: Optical grating cavities in Al 2 O 3 channel waveguides were successfully defined by focused ion beam milling and laser interference lithography as mentioned in this paper, and both methods were shown to be suitable for realizing resonant structures for on-chip waveguide lasers.
Abstract: Optical grating cavities in Al 2 O 3 channel waveguides were successfully defined by focused ion beam milling and laser interference lithography. Both methods are shown to be suitable for realizing resonant structures for on-chip waveguide lasers.
01 Jan 2010
TL;DR: In this article, an integrated Al2O3:Er3+ channel waveguide ring laser was realized on thermally oxidized silicon substrates, where high pump power coupling into and low output power coupling from the ring was achieved in a straightforward design.
Abstract: Integrated Al2O3:Er3+ channel waveguide ring lasers were realized on thermally oxidized silicon substrates. High pump power coupling into- and low output power coupling from the ring is achieved in a straightforward design. Wavelength
selection in the range 1532 to 1557 nm was demonstrated by
varying the length of the output coupler from the ring.
16 May 2010
TL;DR: In this paper, the high gain obtained at the 981-nm zero-phonon line of a WO 4 ) 2 ∶Gd3+, Lu3+, Yb3+ planar waveguide resulted in efficient laser emission in an open cavity configuration.
Abstract: When pumping at a short wavelength of 932 nm, the high gain obtained at the 981-nm zero-phonon line of a KY(WO 4 ) 2 ∶Gd3+, Lu3+, Yb3+ planar waveguide resulted in efficient laser emission in an open cavity configuration.
01 Jan 2010
TL;DR: In this article, Neodymium-doped Al2O3 layers were deposited on thermally oxidized Si substrates and channel waveguides were patterned using reactive-ion etching.
Abstract: Neodymium-doped Al2O3 layers were deposited on thermally oxidized Si substrates and channel waveguides were patterned using reactive-ion etching. Internal net gain on the Nd3+ transitions at 880, 1064, and 1330 nm was investigated,
yielding a maximum gain of 6.3 dB/cm at 1064 nm. Values for the energy-transfer upconversion parameter for different Nd3+
concentrations were deduced.
TL;DR: Large-core, tapered Al/Nd channel waveguides have been fabricated and optical amplification at a wavelength of 880 nm is characterized and use of such rare-earth-ion-doped waveguide amplifiers can provide a solution for compensating the losses occurring in optical interconnects.
Abstract: Large-core, tapered Al 2 O 3 :Nd3+ channel waveguides have been fabricated and optical amplification at a wavelength of 880 nm has been characterized. Amplification in optical backplanes has been demonstrated by inserting such Al 2 O 3 :Nd3+ channel waveguides in between two polymer waveguides. A maximum 0.21-dB internal net gain has been demonstrated in an Al 2 O 3 :Nd3+ waveguide coupled in between two polymer channel waveguides. The gain can be improved by increasing the pump power and adjusting the waveguide geometry and dopant concentration for the chosen pump power. Use of such rare-earth-ion-doped waveguide amplifiers can provide a solution for compensating the losses occurring in optical interconnects.
31 Jan 2010
TL;DR: Co-doping with optically inert Gd3+ and Lu3+ ions improves refractive index contrast and light confinement in WO42:Yb3+ planar waveguides.
Abstract: Co-doping with optically inert Gd3+ and Lu3+ ions improves refractive-index contrast and light confinement in KY(WO4)2:Yb3+ planar waveguides. Lasing with 18 mW threshold and record-high slope efficiency of 82.3% versus absorbed pump power is demonstrated.