Integrated Laser Modulator Research Articles

Photonics-Based Millimeter-Wave Band Remote Beamforming of Array-Antenna Integrated With Photodiode Using Variable Optical Delay Line and Attenuator

For simplification of mobile base station architecture, we present remote beamforming of an array antenna integrated with photodiode based on photonics. Variable optical delay lines (VDLs) and variable optical attenuators (VOAs) are utilized for tailoring the RF phases and amplitudes and radio-over-fiber (RoF) technique is adopted for RF signal transmission. First, we show a simple demonstration of 60-GHz antenna beamforming using VDLs and VOAs with the aim of simplification of RoF signal generation at a control site. Next, we present experimental results on 60-GHz band digital signal transmission at 7 and 14 Gbit/s with beamforming function, in which eight compact antenna modules are arrayed in a row. Finally, we investigate RoF signal generation at 40 GHz utilizing the 1.3- μ m band electroabsorption modulator-integrated laser diode, where an optical filter and an optical amplifier are used to boost the modulation component and the successful formation of various beam patterns by tuning VDL and VOA is shown.

同谱段异频点高稳定四路集成激光器模块

同谱段异频点高稳定四路集成激光器模块

Visible laser emission from a praseodymium-doped fluorozirconate guided-wave chip.

We report visible continuous-wave laser emission at 636 nm from a praseodymium-doped fluorozirconate glass guided-wave chip laser. This ultra-fast laser inscribed gain chip is demonstrated to be a compact and integrated laser module. The laser module, pumped by 442 nm GaN laser diodes, generates >8 mW lasing output with a beam quality of Mxy2∼1.15×1.1(±0.1). To the best of our knowledge, this is the first visible laser emission from a glass-based waveguide chip laser.

A Widely Tunable Narrow Linewidth RF Source Integrated in a Heterogeneous Photonic Module

Generating radio-frequency signals over the entire spectrum, from 1 to 100 GHz, typically requires the use of multiple oscillators designed only for specific narrow bands of operation within that spectrum. An optoelectronic system based on modulation side-band-injection-locked lasers is capable of generating RF frequencies tunable over a span of more than seven octaves with low phase noise . We present the results of our efforts to develop a heterogeneously integrated version of this system based on a silicon-photonic integrated circuit coupled to III-V semiconductor gain chips. Towards that end, we have successfully demonstrated an integrated laser module and achieved tunable RF generation with a ~ 1 Hz linewidth.

59.4: WITHDRAWN: 60.1: Integrated Flat Package RGB Laser Module Using Si‐Platform Technology

AbstractWe propose a novel fiber pigtailed integrated laser module for pico‐projector and near‐to‐eye display applications using Si‐platform technology based on surface activation bonding. The module consists of synthetic blue (B) and green (G) second harmonic generation (SHG) lasers and a direct red (R) laser diode (LD). We also present its basic performance and discuss its further integration capabilities.

Performance Improvement of 40-Gb/s Electroabsorption Modulator Integrated Laser Module With Two Open-Circuit Stubs

In this letter, we propose and demonstrate a compact, low-cost, and easy to manufacture microstrip line with two open-circuit stubs to alleviate impedance mismatching of a packaged 40-Gb/s electroabsorption modulator integrated laser (EML) module. For comparison, two 1550-nm EML modules are fabricated, the only difference being that one of them is made with open-circuit stubs, while the other is not. It is revealed that the open-circuit stubs technique expands the 3-dB modulation bandwidth from 25.2 to 33.6 GHz, and the suppression of the input return loss below -10 dB in the range of the higher frequency of the sub-assembly with chip is also successfully demonstrated. Further evidence showing the advantage of the EML module with open-circuit stubs over the one without open-circuit stubs include the effective reduction in the RMS jitter of the eye diagram from 1.4 to 1.2 ps, as well as the improvement of the sensitivity, which changes from -8.3 to -9.5 dBm measured with the same receiver.

High-Frequency Modeling and Optimization of E/O Response and Reflection Characteristics of 40 Gb/s EML Module for Optical Transmitters

A complete high-frequency small-signal circuit model of a 40 Gb/s butterfly electroabsorption modulator integrated laser module is presented for the first time to analyze and optimize its electro-optic (E/O) response and reflection characteristics. An agreement between measured and simulated results demonstrates the accuracy and validity of the procedures. By optimizing the bonding wire length and the impedance of the coplanar waveguide transmission lines, the E/O response increases approximately 5% to 15% from 20 GHz to 33 GHz, while the signal injection efficiency increases from approximately 15% to 25% over 18 GHz to 35 GHz.

40 Gb/s Traveling-Wave Electroabsorption Modulator-Integrated DFB Lasers Fabricated Using Selective Area Growth

In this paper, we present the fabrication of 40 Gb/s traveling-wave electroabsorption modulator-integrated laser (TW-EML) modules. A selective area growth method is first employed in 40 Gb/s EML fabrication to simultaneously provide active layers for lasers and modulators. The 3 dB bandwidth of a TW-EML module is measured to be 34 GHz, which is wider than that of a lumped EML module. The 40 Gb/s non-return-to-zero eye diagram shows clear openings with an average output power of +0.5 dBm.

Integration and Characteristics of 40-Gb/s Electroabsorption Modulator Integrated Laser Module With a Driver Amplifier and Bias Tees

Integration of a 40-Gb/s electroabsorption modulator integrated distributed feedback (DFB) laser (EML) module with a driver amplifier and bias tee was investigated. For the EML fabrication the selective area growth (SAG) technique was adopted for the first time. It is shown that, with the SAG technique, the 3-dB bandwidth of about 45 GHz was measured in the electrical to optical response, and the return loss (S11) of below -10 dB was achieved for up to 50 GHz . To integrate a bias tee within the module, a right-angle bent coplanar waveguide (CPW) was developed. The right-angle bent CPW was characterized with S11 of below - 10 dB for up to 35 GHz and insertion loss (S21) of about -1.4 dB for up to 40 GHz . The whole integrated module including the EML, a driver amplifier, and bias tee was characterized under the conditions of an operating temperature of 25degC, the modulator bias of 1.4 V, and the DFB laser current of 40 mA. S11 of below -10 dB was obtained for up to 14 GHz and the measured electrical-to-optical response has 3-dB bandwidth of about 20 GHz.

Selective-area MOVPE growth for 10 Gbit/s electroabsorption modulator integrated with a tunable DBR laser

We have designed and fabricated electroabsorption modulator integrated monolithically with a distributed Bragg reflector laser using selective area growth (SAG) by metalorganic vapor phase epitaxy (MOVPE). Through the bandgap engineering due to the growth rate enhancement and compositional variation from the difference of migration and/or diffusion length of species by various SAG mask pattern, we have achieved the photoluminescence peak wavelengths of active layer in the laser, modulator, and Bragg grating regions to 1.557, 1.503, and 1.442 μm, respectively. The electroabsorption modulator-integrated laser shows a good performance including threshold current of below 6 mA, output power of 5 mW for 45 mA current injected in the active region, and high side-mode suppression ratio over 45 dB with the 3-dB modulation bandwidth over 11 GHz.

Transmission over 80 km at 10 Gb/s Using the Amplifier- and Modulator-Integrated Laser Diode

We demonstrated the transmission over 80 km at 10 Gb/s by using the amplifier and electroabsorption-modulator integrated laser diode. Tilt-facet antireflection window is implemented, inside of which a monitor photodiode is monolithically integrated for accurate power regulation. To better control the amplifier-input power and to reduce the feedback of the amplified spontaneous emission, an attenuator is incorporated by means of the inner-window. By amplifying the modulated signal and compensating modulator-chirp by gain-saturation in the amplifier, high power optical transmission is achieved from a device with -10 dB attenuation at total laser and amplifier currents of 200 mA.

Measurement-based model for the modulation properties of an integrated laser modulator and its application to systems with tight optical filtering

An efficient and accurate model of a distributed feedback laser integrated with an electroabsorption modulator (integrated laser modulator) is presented. The model is based on an experimental characterization of the absorption, adiabatic chirp, transient chirp, and intensity modulation (IM) frequency response. Agreement between calculated and measured results for the large-signal modulation dynamics (intensity and chirp) is obtained. By implementing the model in a system simulation tool, it is shown that the adiabatic chirp due to reflection from the modulator facet must be considered to accurately assess the performance of systems with dispersive fiber and tight optical filtering.

Design of amplifier- and modulator-integrated laser diode for 10-Gb/s 80-km transmission

We present the amplifier- and modulator-integrated laser diode designed for 10-Gb/s transmission over 80-km distance. An antireflection window structure is implemented at the tilt facet of the amplifier to reduce optical feedback by 40 dB. A monitor photodiode is monolithically integrated in the antireflection window region for accurate power regulation. To better control the amplifier input power and to reduce the feedback of amplified spontaneous emission, an attenuation inner-window is incorporated by removing a section of the waveguide. The reproducibility of the chip fabrication process is tested to confirm the design margin. Through amplifying the modulated signals and reducing modulator chirp by amplifier saturation, high-power optical transmission is demonstrated.

Attenuation inner-window in the amplifier- and modulator-integrated laser diode

To better control the input power of an amplifier, which is monolithically integrated with an electroabsorptive-modulated laser, an inner window is implemented by removing a section of the waveguide to realize an attenuator. It also reduces the effect of amplified spontaneous emission on the integrated laser. Attenuation around -10 dB is obtained by adjusting the length of the inner window. Because of different focal depths, unguided stray light from the inner window is not coupled to a fiber on which the amplifier output is focused through a lens.

Monitor-Photodiode Integration in the Amplifier- and Modulator-Integrated DFB Laser Diode

Monitor photodiode (MPD) is monolithically integrated in the antireflection output window region of the amplifier- and modulator-integrated laser diode. The MPD is electrically isolated from the other components by semi-insulating InP regrowth with total leakage current less than 1 μA. The MPD responsivity to the output power is tailored through its location and size, and about half decibel power loss is achieved for 4% responsivity. The reliability is demonstrated through the accelerated aging test.

A Highly Stable and Reliable Wavelength Monitor Integrated Laser Module Design

Three existing wavelength monitor integrated laser module designs are evaluated. The shortcomings of these designs are resolved by a unique design that eases alignment tasks and greatly enhances the wavelength stability and the wavelength tunability. For example, the wavelength drift over case temperature is 16 times smaller than the best result of previous reports. With the incorporation of thermal compensation, the temperature-induced wavelength drift of the etalon is eliminated. In anticipation, this design enables a worst overall wavelength-drift of 4.41 pm after 25 years of usage to be achieved.

Wavelength conversion by dual-pump four-wave mixing in an integrated laser modulator

Dual-pump four-wave mixing for wavelength conversion is demonstrated using a distributed-feedback laser integrated with two electroabsorption modulators. The device acts as both the conversion medium and the dual-pump source. For a given input probe signal, output conjugate signal-to-noise ratio values of greater than 10 dB were measured over probe wavelengths ranging from 1557 to 1564 nm for a probe-conjugate detuning of 0.5 nm.

Study on the reliability of an InP/InGaAsP integrated laser modulator

Ridge Integrated Laser Modulator (ILM) devices were fabricated using a butt-coupling technology based on two gas source molecular beam epitaxy. A complete stability evaluation was undertaken, including a reliability study on discrete lasers, discrete modulators and integrated devices. The butt-coupling integration process does not affect the reliability of the integrated devices.

Stability evaluation of a ridge-integrated laser modulator based on a butt-coupling approach

Ridge integrated laser modulator (ILM) devices were fabricated using a butt-coupling technology based on two-gas-source molecular-beam epitaxy. A complete stability evaluation was undertaken, including a reliability study on discrete lasers, discrete modulators, and integrated devices. High temperature, high current, and high voltage were applied for over 1900 h without significant evolution of the electrooptical characteristics. A functional aging test at the current corresponding to a 2-mW output power and the modulator bias necessary to reach the maximum extinction ratio was performed for more than 1500 h. The butt-coupling region does not affect the reliability of the integrated devices.

Pulse generation by harmonic modulation of an integrated DBR laser-modulator

34, 17 and 14 ps pulses have been generated at repetition rates of 2.5, 5 and 10 GHz, respectively, from an integrated laser modulator at 1.5 µm. Pulse widths were significantly reduced by modulating at both the fundamental and the second harmonic frequencies.