We report on InP-based high power modified uni-traveling carrier (MUTC) photodiodes heterogeneously integrated on silicon on diamond (SOD) waveguides. Typical dark currents of MUTC photodiodes on SOD waveguides are 20 nA at - 5 V bias voltage. A 50-μm long photodiode has an internal responsivity of 1.07 A/W at 1550 nm wavelength. The bandwidths of photodiodes with active areas of 14×25 μm2, 14×50 μm2, 14×100 μm2 and 14×150 μm2 are 22 GHz, 16 GHz, 10 GHz and 7 GHz, respectively. The maximum output RF powers of 14×100 μm2 photodiodes are 13 dBm, 14.4 dBm and 15.3 dBm at 10 GHz, respectively. The maximum DC dissipated power is 0.67 W. To our knowledge, this is the first demonstration of III-V photodiodes integrated on SOD waveguides.
Aurion's heterogeneous integration platform combines best-in-class passive and active devices in a cost-effective manufacturing process for both military and commercial systems. The resulting silicon photonics chips can be intimately integrated with advanced electronics to enable new system-in-package capability.
Aurrion’s heterogeneous integration process enables high performance active components such as lasers, modulators, and photodetectors to be elegantly integrated on a silicon photonics platform with high performance passive components. This platform also offers the unique capability to combine different types of active devices with separately optimized materials on the same wafer, die, and photonic integrated circuit. Similarly, devices and photonic integrated circuits operating in different wavelength bands can be formed within the same wafer and die. Experimental demonstrations show that these active components can achieve performance on par with commercially available discrete III-V components. In this paper we will discuss the advantages of Aurrion’s heterogeneous integration platform and discuss prototype demonstrations.
Photonic Integrated Circuits (PICs) have been dichotomized into circuits with high passive content (silica
and silicon PLCs) and high active content (InP tunable lasers and transceivers) due to the trade-off in material
characteristics used within these two classes. This has led to restrictions in the adoption of PICs to systems in which
only one of the two classes of circuits are required to be made on a singular chip. Much work has been done to
create convergence in these two classes by either engineering the materials to achieve the functionality of both
device types on a single platform, or in epitaxial growth techniques to transfer one material to the next, but have yet
to demonstrate performance equal to that of components fabricated in their native substrates. Advances in waferbonding
techniques have led to a new class of heterogeneously integrated photonic circuits that allow for the
concurrent use of active and passive materials within a photonic circuit, realizing components on a transferred
substrate that have equivalent performance as their native substrate. In this talk, we review and compare advances
made in heterogeneous integration along with demonstrations of components and circuits enabled by this technology.
A summary of current work involving the development of high performance, wavelength-tunable integrated optical transmitters for analog applications is given. The performance of sampled-grating DBR lasers integrated with an SOA and an electroabsorption or Mach-Zehnder modulator is evaluated in terms of E/O conversion efficiency, noise performance and dynamic range. Optimization options to maximize either gain, noise figure or spurious-free dynamic range in analog link applications are discussed. It is shown how the combination of chip-scale integration and the use of bulk waveguide Franz-Keldysh absorption allows coupling of a large optical power level into the electroabsorption modulator, and its effects on the modulation response and analog link performance. Link results on an integrated SGDBR-SOA-EAM device includes a sub-octave SFDR in the 125 to 127 dB/Hz4/5 range and a broadband SFDR of 103-107 dB/Hz2/3 limited by third order intermodulation products or 95-98 dB/Hz1/2, limited by second order intermodulation products, over a 1528 to 1573 nm wavelength range.
Tunable semiconductor lasers have been listed in numerous critical technology lists for future optical communication systems. Lasers with full band tuning ranges (C or L) allow reduction of the inventory cost and simplify deployment and operation of existing systems in addition to enabling wavelength agile networking concepts in future systems. Furthermore, monolithic integration of full band tunable lasers with modulators to form complete transmitters offers the most potential for reducing system size, weight, power consumption, and cost. This paper summarizes design, fabrication technology, and performance characteristics of widely tunable CW sources and transmitters based on chip scale integration of a Sampled Grating Distributed Bragg Reflector (SG DBR) laser with a Semiconductor Optical Amplifier (SOA) and Electroabsorption (EA) or Mach Zehnder (MZ) modulator. Widely tunable CW sources based on SG-DBR lasers exhibit high fiber coupled output power (20 mW CW) and side mode suppression ratio (>40 dB), low relative intensity noise (below -140 dB/Hz) and line width (<5 MHz) across a 40 nm C-band tuning range. Characteristics of EA-modulated optical transmitters include fiber-coupled time-averaged powers in excess of 5 dBm, RF extinction ratios > 10 dB, and error-free transmission over 350 km of standard fiber at 2.5 Gb/s across a 40 nm tuning range. Monolithic integration of widely tunable lasers with MZ modulators allow for further extension of bit rate (10 Gb/s and beyond) and transmission distances through precise control of the transient chirp of the transmitter. Systematic investigations of accelerated aging confirm that reliability of these widely-tunable transmitters is sufficient for system deployment.
Integration of active optical components typically serves five goals: enhanced performance, smaller space, lower power dissipation, higher reliability, and lower cost. We are manufacturing widely tunable laser diodes with an integrated high speed electro absorption modulator for metro and all-optical switching applications. The monolithic integration combines the functions of high power laser light generation, wavelength tuning over the entire C-band, and high speed signal modulation in a single chip. The laser section of the chip contains two sampled grating DBRs with a gain and a phase section between them. The emission wavelength is tuned by current injection into the waveguide layers of the DBR and phase sections. The laser light passes through an integrated optical amplifier before reaching the modulator section on the chip. The amplifier boosts the cw output power of
the laser and provides a convenient way of power leveling. The modulator is based on the Franz-Keldysh effect for a wide band of operation. The common waveguide through all sections minimizes optical coupling losses. The packaging of the monolithically integrated chip is much simpler compared to
a discrete or hybrid solution using a laser chip, an SOA, and an external modulator. Since only one optical fiber coupling is required, the overall packaging cost of the transmitter module is largely reduced. Error free transmission at 2.5Gbit/s over 200km of standard single mode fiber is obtained with less than 1dB of dispersion penalty.
While tunable lasers have been a focus of research and development efforts for over 10 years, they have only recently gained market acceptance in optical transport and networking. Tunable lasers offer many compelling advantages over fixed wavelength solutions in optical networks in that they reduce inventories, allow dynamic wavelength provisioning, and simplify network control software. More interesting, is that tunable lasers have been featured in optical network development efforts in every segment: access/enterprise, metropolitan, and long haul networks leading to a variety of desired specifications and approaches. In fact, the term 'tunable laser' has come to describe an increasingly broad range of technologies from monolithic semiconductor lasers, to MEMS (Micro-Electro-Mechanical Systems) based lasers and fiber lasers. This presentation will focus on monolithic, widely-tunable lasers which are promising candidates to satisfy the needs of all the market segments mentioned.
In recent WDM communication systems, a wavelength-selective filter or detector is required at receiver end to pick up desired channels from incoming data streams. In addition to the wavelength-selectivity, one also desires these devices to have wavelength tunability such that the entire system is reconfigurable. Filters and receivers based on arrayed waveguide grating (AWG) structures have been developed. Even though AWG devices demonstrated good side-lobe suppression ratios (SSRs), they are not tunable. Devices based on vertically stacked grating-assisted codirectional couplers (GACC) have therefore attracted great attention due to the wide and fast wavelength tunability. However, the response of a one-stage GACC device with a uniform coupling strength across the entire filter section is a sinc2-like function which limits its SSR to less than 9 dB. It is well known that there is roughly a Fourier transform relationship between the coupling coefficient distribution and the filter response. Therefore, apodizing the coupling strength along the filter can effectively suppress the side-lobes. In this paper, we report on the apodization of the coupling strength in the GACC filter by varying the grating duty ratio. Using this technique in an integrated wavelength-selective receiver, we demonstrate a device with a 40 nm tuning range and a 16 dB SSR. A schematic drawing of the integrated apodized GACC receiver is shown in Figure 1. The device includes a semiconductor optical amplifier (SOA), a two-stage GACC optical filter, and a waveguide photodetector on InP/InGaAsP based materials. The operating principle of the device is explained as the following: Input light is first coupled into the top waveguide and is amplified the SOA. It is then filtered by two apodized GACC filters in series. At the wavelength where phase matching condition is satisfied, light will be coupled down to the bottom waveguide and then back up to the top waveguide. Finally, it will be detected by the waveguide photodetector. The middle of the top waveguide is broken by a 30 degree tilted etched groove. The tilted groove deflects any uncoupled light laterally to avoid multiple reflections of unwanted signals to the detector.
We discuss our measurements on thermal impedance and thermal crosstalk of etched-pillar vertical-cavity lasers and laser arrays. The average thermal conductivity of AlAs-GaAs Bragg reflectors is estimated to be 0.28 W/(cmK) and 0.35W/(cmK) for the transverse and lateral direction, respectively. Lasers with a Au-plated heat spreading layer exhibit a 50% lower thermal impedance compared to standard etched-pillar devices resulting in a significant increase of maximum output power. For an unmounted laser of 64 micrometer diameter we obtain an improvement in output power from 20 mW to 42 mW. The experimental results are compared with a simple analytical model showing the importance of heat sinking for maximizing the output power of vertical-cavity lasers.