Tunable Distributed Bragg Reflector Laser Research Articles

Enhanced direct modulation bandwidth in a tunable DBR laser with an equivalent phase shift grating

A high speed directly modulated and tunable distributed Bragg reflector laser is proposed based on an equivalent phase shift Bragg grating. By inserting a uniform waveguide in the middle of Bragg grating section, a notch is formed on reflectivity spectrum of the grating, and the photon-photon resonance (PPR) effect could then be introduced to extend modulation bandwidth. An independent electrode is also added for controlling the equivalent phase shift, which plays a key role in the design to introduce the PPR effects, and ensure compatibility with wavelength tuning. Stability, tunability and small signal response of the laser are numerically investigated, 40 GHz direct modulation bandwidth and 7 nm tuning range are obtained, indicating that the laser designed could achieve a large modulation bandwidth within a certain wavelength tuning range.

Monolithic Passive−Active Integration of Epitaxially Grown Quantum Dot Lasers on Silicon

Quantum dot (QD) lasers epitaxially grown on Si have already been demonstrated to show record low threshold, high temperature tolerance, and low feedback sensitivity. When grown on the silicon photonic chip and integrated with Si waveguides (WGs), QD lasers offer considerable economical and foundry‐scalable solutions to on‐chip light sources. Yet, a technology that enables both growth and integration of QD lasers on a silicon photonic chip has not been demonstrated. Herein, a novel device platform which enables integration of the QD active region with passive WG structures is designed. By doing so, complex and high‐performance lasers such as distributed Bragg reflector lasers, mode‐locked lasers, and sampled grating distributed Bragg reflector tunable lasers are demonstrated in this platform. The same laser epitaxial stack can be easily grown on the substrate of a silicon photonic chip to allow light coupling from QD laser cavities to the silicon WGs.

A 1.6-[formula omitted]m widely tunable distributed Bragg reflector laser diode based on InGaAs/InGaAsP quantum-wells material

We demonstrate a widely tunable InGaAs quantum-wells (QWs) distributed Bragg reflector (DBR) laser, in which the DBR section was realized by using butt-jointed InGaAsP (λ=1.46μm) material. In the device process, we explored an optimal chemical etchant applied in the butt-jointed active–passive integration technology. A wide tuning range of 10.7 nm with 19 consecutive channels is obtained with a single tuning current at room temperature (RT). With the help of the heat sink temperature, the tuning range is expanded to 16 nm. A side mode suppression ratio (SMSR) of higher than 34 dB is obtained for all channels at 5 °C to 45 °C. A six-wavelength laser array that can cover a wavelength tuning range of 41.6 nm at 20 °C with a side mode suppression ratio higher than 37 dB in all channels is demonstrated by varying the grating periods. It is a promising light source for methane or multispecies gas detection.

A Widely Tunable Three-Section DBR Lasers for Multi-Species Gas Detection

We demonstrate a widely tunable distributed Bragg reflector (DBR) laser operating at 1.8-µm, in which the DBR section was butt-jointed InGaAsP (λ = 1.45 μm) material. Through current and temperature tuning, a widely tuning range of over 11 nm with a side mode suppression ratio (SMSR) higher than 30 dB is obtained. Utilizing this DBR laser, the water and methane detection experiment has been successfully implemented, which illustrates the potential capacity of such DBR laser as the light source used for multispecies gas sensing. The work also illustrates that the butt-joint active-passive integration technology developed for the InGaAsP quantum-wells (QWs) can be successfully applied in the InGaAs QWs.

Up to 50 Gb/s modulation of an EAM integrated widely tunable DBR laser

An electro-absorption modulator (EAM) integrated widely tunable distributed Bragg reflector (DBR) laser working at 1.5 µm is reported. By utilizing the RF resonance between the bonding wire and the EAM, a 28 GHz modulation bandwidth is obtained. The device is modulated with up to 50 Gb/s NRZ data. At 28 Gb/s, the power penalty to obtain a 10-10 bit error rate (BER) after a 5 Km standard single mode fiber transmission is less than 0.7 dB. Because the DBR material has a long bandgap wavelength, the wavelength tuning range of the laser is larger than 12 nm. The DBR laser is a promising low cost tunable light source for future high capacity wavelength division multiplexing (WDM) optical communication systems.

A10 Gb/s 1.5 μm Widely Tunable Directly Modulated InGaAsP/InP DBR Laser**Supported by the National Key Research and Development Program of China (Grant Nos. 2017YFF0206103, 2016YFB0402301, and 2018YFB2200801) and the National Natural Science Foundation of China (Grant Nos. 61635010, 61320106013, 61474112, and 61574137).

We report 10 Gb/s data transmissions using a packaged two-section InGaAsP/InP distributed Bragg reflector (DBR) laser. The tunable DBR laser has a wavelength tuning range of 12.12 nm. The DBR laser has greater than 10.84 GHz 3-dB direct modulation bandwidth within the wavelength tuning range. The 10 Gb/s data transmissions are performed at up to a distance of 30-km.

Continuous Wave THz System Based on an Electrically Tunable Monolithic Dual Wavelength Y-Branch DBR Diode Laser

We analyse the use of a tunable dual wavelength Y-branch DBR laser diode for THz applications. The laser generates electrically tunable THz difference frequencies in the range between 100 and 300 GHz. The optical beats are tuned via current injection into a micro-resistor heater integrated on top of one of the distributed Bragg reflector (DBR) section of the diode. The laser is integrated in a homodyne THz system employing fiber coupled ion-implanted LT-GaAs log spiral antennas. The applicability of the developed system in THz spectroscopy is demonstrated by evaluating the spectral resonances of a THz filter as well as in THz metrology in thickness determination of a polyethylene sample.

1.3-µm and 10-Gbps tunable DBR-LD for low-cost application of WDM-based mobile front haul networks.

We report a 1.3-µm and 10-Gbps tunable distributed Bragg reflector laser diode (DBR-LD) for the low-cost application of a wavelength division multiplex based mobile front-haul network. The device consists of gain, phase control, and DBR sections, implemented using a butt-coupling method through a monolithic integration and through the introduction of an etched mesa planar buried hetero-structure in a waveguide structure. From the work, a 560-µm long DBR-LD with a 220-µm long micro-heater DBR section has a threshold current of 10 mA ± 1 mA and a tuning range of more than 15 nm within a heater injection current of ∼100 mA. Spectral and dynamic tests for this LD show 16 channels spaced a wavelength grid of 0.8 nm with a side mode suppression ratio of greater 40 dB and clear eye openings with a dynamic extinction ratio of over 5.4 dB at an operating current of 60 mA.

High-Resolution Optical Frequency Synthesis Using an Integrated Electro-Optical Phase-Locked Loop

Optical frequency synthesizers have widespread applications in optical communication, sensing, and ranging systems. These synthesizers typically consist of an electro-optical phase-locked loop (EOPLL) that phase locks a widely tunable laser (TL) to the teeth of a highly stable optical frequency comb. In this paper, a partially integrated optical frequency synthesizer is reported, where a stable and low-noise frequency comb is used as the optical reference. In the proposed architecture, frequency synthesis is done in two phases. In a coarse tuning phase, a widely tunable distributed Bragg reflector laser is continuously tuned by adjusting its mirrors and phase section currents. While the laser is being tuned, an indexing system detects and counts the number of passing comb teeth. Coarse tuning is concluded when the TL reaches the target comb tooth. Following the coarse tuning phase, a heterodyne integrated EOPLL phase locks the TL to the selected comb tooth. Under the phase lock condition, fine frequency tuning is performed by adjusting the frequency of an RF local oscillator. The proposed synthesizer has the capability of synthesizing optical frequencies over a 5-THz range with a coarse tuning speed of 0.5 THz/s and coarse and fine tuning resolutions of 20 MHz and less than 1 Hz, respectively.

10 Gb/s Data Transmissions Using a Widely Tunable Directly Modulated InGaAlAs/InGaAsP DBR Laser

We report data transmissions using a packaged two-section distributed Bragg reflector (DBR) laser, which has InGaAlAs multi-quantum wells as the gain material. The tunable DBR laser has a wavelength tuning range of 11.44 nm. The DBR laser has uniform 3-dB direct modulation bandwidth (over 12 GHz) within the over 11-nm wavelength tuning range; 10-Gb/s data transmissions are performed at up to 25-km distance and different wavelength emissions at 25 °C and 50 °C.

Data Transmission Using a Directly Modulated Widely Tunable DBR Laser With an Integrated Ti Thin Film Heater

We present data transmission using a directly modulated distributed Bragg reflector (DBR) laser having an integrated Ti thin film heater in the DBR section and butt-jointed InGaAsP as DBR material. By combining DBR current tuning and thermal tuning effects, an over 16 nm wavelength tuning range is obtained. 5 Gb/s data transmissions are conducted at up to 25 km distance and different wavelengths. In the fabricated device, the butt-jointed InGaAsP material is also used for the formation of an integrated photodiode for monitoring the light power of the device.

Research on the influence of laser-tuning characteristics on all-fiber distributed Bragg reflector self-mixing rangefinder

We proposed an all-fiber tunable distributed Bragg reflector (DBR) laser rangefinder, which realized high-accuracy measurement of the absolute distance in the range of 1.88 to 3.33 m based on the self-mixing effect. The theoretical analysis of the all-fiber tunable DBR laser shows that wavelength tuning range and frequency of the laser can influence the measurement range and resolution. In addition, the experimental results indicate that the influence factors of measurement accuracy and sensitivity in absolute distance measurement are modulation response linearity, experimental equipment, and circuit bandwidth, which is in good agreement with theory analysis. Moreover, increasing the linear wavelength tuning range of the tunable DBR laser is an essential method to improve the measurement accuracy and sensitivity of the absolute distance measurement system.

Transmission of 20 Gb/s PAM-4 signal over 20 km optical fiber using a directly modulated tunable DBR laser

We report 20 Gb/s transmission of four-level pulse amplitude modulation (PAM) signal using a directly modulated tunable distributed Bragg reflector (DBR) laser. Transmission distance over 20 km was achieved without using optical amplifiers and optical dispersion compensation modules. A wavelength tuning range of 11.5 nm and a 3 dB bandwidth greater than 10 GHz over the entire wavelength tuning range were obtained.

Temperature-Tolerant Wavelength-Setting and -Stabilization in a Polymer-Based Tunable DBR Laser

In this paper, we present a method of self-detection of mode hops in a distributed Bragg reflector tunable laser using the voltage drop in the active section as a monitoring signal. Based on this method, a wavelength setting and stabilization algorithm that is tolerant to temperature variations is proposed. Wavelength locking for a period of more than seven days with an accuracy better than ±1.25 GHz has been achieved, meeting the ITU-T standard for 25 GHz channel spacing. Under forced changes in the operation temperature from 15° to 60°, with variations of 0.1°/s, the maximum allowed deviation of ±2.5 GHz for the ITU-T standard with 50 GHz channel spacing was kept.

Widely Tunable Two-Section Directly Modulated DBR Lasers for TWDM-PON System**Supported by the National Key Project under Grant No 2016YFB0402301, the National High Technology Research and Development Program of China under Grant No 2013AA014502, and the National Natural Science Foundation of China under Grant Nos 61635010, 61320106013, 61474112, 61321063 and 61274071.

Wavelength tunable and directly modulated distributed Bragg reflector (DBR) lasers with butt-joint technology are designed, fabricated and characterized. The DBR laser consists of a gain section and a DBR section. To increase the electrical isolation between the gain section and the DBR section, parts of a p-doped material in the isolation region are etched off selectively. Over 2 kΩ isolation resistance is realized ultimately without the need of ion implantation, which simplifies the fabrication process. The laser exhibits high speed modulation with a large tunable range. The 3 dB direct modulation bandwidth of the device is over 8 GHz in a 12 nm tunable range. This widely tunable DBR laser with the simple structure is promising as a colorless light source for the next-generation time and wavelength division multiplexed passive optical network (TWDM-PON) systems.

High-speed directly modulated widely tunable two-section InGaAlAs DBR lasers.

We report widely tunable two-section distributed Bragg reflector (DBR) lasers, which have InGaAlAs multiple quantum wells (MQWs) as the gain material. By butt-jointing InGaAsP, which has a photoluminescence wavelength of 1.4 μm as the material of the DBR section, a wavelength tuning range of 12 nm can be obtained by current injection into the DBR section. The direct modulation bandwidth of the lasers is greater than 10 GHz over the entire wavelength tuning range up to 40°C. Compared with InGaAsP DBR lasers having the same structure, the InGaAlAs lasers have smaller variations in both the threshold current and slope efficiency with the temperature because of the better electron confinement in the InGaAlAs MQWs. Moreover, the DBR-current-induced decreases in the modulation bandwidth and side mode suppression ratio (SMSR) of the optical spectra are notably smaller for the InGaAlAs lasers than for the InGaAsP lasers.

GaAsP tunable distributed Bragg reflector laser with indium tin oxide thin-film heater

A GaAsP quantum well tunable distributed Bragg reflector (DBR) laser with a thin-film heater above a DBR grating was designed and fabricated. As a result of the optimization of the DBR grating to obtain both high reflectivity and sharp wavelength selectivity, single-mode lasing with an output power of 54 mW and a side-mode suppression ratio of 43 dB was obtained. By forming the transparent thin-film heater at a distance of 0.1 µm above the DBR grating, the DBR grating was heated locally and efficiently, and a wide wavelength tuning range of 5.2 nm was achieved by heating with a heater power as low as 160 mW.

Integrated Reconfigurable Coherent Transmitter Driven by Binary Signals

A novel InP monolithically integrated transmitter composed of a tunable distributed Bragg reflector laser and a reconfigurable IQ modulator with tunable power splitters has been designed, fabricated and tested. The transmitter architecture allows, in principle, generation of offset-free phase-amplitude constellations such as QPSK and 16-QAM by employing simple binary signals with equal peak-to-peak amplitude. The adoption of tunable splitters enables reconfiguration of the output constellation and compensation for imperfections related to fabrication. The solution presented in this paper minimizes the complexity of the employed architecture together with the one of the driving signals. Numerical analysis has been conducted to predict system behavior and evaluate the impact of sub-optimum settings that might occur in a real implementation. Experimental results show the generation PM-QPSK signals at 10 Gbaud when using the integrated DBR laser and at 32 Gbaud when using an external low-phase-noise laser. Unfortunately, the generation of 16-QAM signals, which can be in principle realized with this novel PIC, was not possible in practice because of significant spurious amplitude modulation in the electro-optic phase modulators.

Electroabsorption-modulated widely tunable DBR laser transmitter for WDM-PONs.

We present an InP based distributed Bragg reflector (DBR) laser transmitter which has a wide wavelength tuning range and a high chip output power for wavelength division multiplexing passive optical network (WDM-PON) applications. By butt-jointing InGaAsP with 1.45 µm emission wavelength as the material of the grating section, the laser wavelength can be tuned for over 13 nm by the DBR current. Accompanied by varying the chip temperature, the tuning range can be further enlarged to 16 nm. With the help of the integrated semiconductor optical amplifier (SOA), the largest chip output power is over 30 mW. The electroabsorption modulator (EAM) is integrated into the device by the selective-area growth (SAG) technique. The 3 dB small signal modulation bandwidth of the EAM is over 13 GHz. The device has both a simple tuning scheme and a simple fabrication procedure, making it suitable for low cost massive production which is desirable for WDM-PON uses.

Fast Wavelength Switching 6 GBd Dual Polarization 16QAM Digital Coherent Burst Mode Receiver

A commercially available digital supermode distributed Bragg reflector tunable laser is employed as a fast wavelength switching local oscillator (LO) in a dual polarization (DP) 16-quadrature amplitude modulation (16QAM) coherent burst mode receiver. A digital coherence enhancement technique is used to compensate both the Lorentzian and non-Lorentzian distributed phase noise of the tunable LO laser. It is shown that differential decoding is not sufficient to overcome the substantial bit errors caused by the LO laser phase noise. However, the coherence enhancement technique enables the reception of low symbol rate DP-16QAM bursts, with an average optical signal to noise ratio penalty of 3.5 dB observed relative to theory at the forward error correction threshold (1.5×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-2</sup> ).