Distributed Bragg Reflector Laser Research Articles

Photonic-assisted wideband microwave frequency measurement based on optical heterodyne detection

Photonic-assisted wideband microwave frequency measurement based on optical heterodyne detection

Low-power-consumption modulation of short-cavity DBR laser on SiO2/Si substrate

We developed short-active-length distributed Bragg reflector (DBR) lasers to reduce the power consumption of chip-to-chip optical interconnects. These lasers have buried bulk InGaAsP waveguides to increase the coupling efficiency between the active region and DBR to 99.79% from the 98.14% of our previous DBR lasers that had InP channel waveguides. We achieved continuous wave operation of 5- to 80-µm active-length DBR lasers and the 5-µm-long laser consumed 24 fJ/bit with a 10-Gbps NRZ signal. The threshold current of the 5-µm laser was 51 µA, which compares favorably to our previous 10-µm DBR lasers with a threshold current of 170 µA.

High-speed spectrum demodulation of fiber-optic Fabry–Perot sensor based on scanning laser

A high-speed spectrum demodulation method with a large dynamic range for fiber-optic Fabry–Perot sensor is presented. The demodulation system only consists of a near-infrared distributed Bragg reflector (DBR) laser, a fiber circulator, a photodetector and a signal processing circuit. By quickly cyclically setting the grating current and phase current of the DBR laser, the laser wavelength is scanned with a repetition frequency of 2 kHz. The signal processing circuit controls the current of the laser and performs spectrum demodulation simultaneously. Spectral demodulation mainly includes normalization of interference spectrum, fast Fourier transform, phase estimation and cavity length calculation. The displacement stage and piezoelectric ceramics were used to remove the static cavity length and dynamic cavity length of the Fabry–Perot cavity. Experimental results show that the demodulation resolution reaches 0.15 nm. Benefiting from the high spectral detection resolution, a large demodulation range is achieved to be 0.3–13 mm. Compared with the demodulation systems based on spectrum modules, this solution significantly reduces the cost, simplifies the algorithm and improves the dynamic range.

Physical-layer key distribution using synchronous complex dynamics of DBR semiconductor lasers

Common-signal-induced synchronization of semiconductor lasers with optical feedback inspired a promising physical-layer key distribution with information-theoretic security and potential in high rate. A significant challenge is the requirement to shorten the synchronization recovery time for increasing the key rate without sacrificing the operation parameter space for security. Here, open-loop synchronization of wavelength-tunable multi-section distributed Bragg reflector lasers is proposed as a solution for physical-layer key distribution. Experiments show that the synchronization is sensitive to two operation parameters, i.e., currents of grating section and phase section. Furthermore, fast wavelength-shift keying synchronization can be achieved by direct modulation on one of the two currents. The synchronization recovery time is shortened by one order of magnitude compared to close-loop synchronization. An experimental implementation is demonstrated with a final key rate of 5.98 Mbit/s over 160 km optical fiber distance. It is thus believed that fast-tunable multi-section semiconductor lasers open a new avenue for a high-rate physical-layer key distribution using laser synchronization.

The Versatile Applications of Distributed Bragg Reflector (DBR) Lasers: Sensing, Communication, And Beyond

Distributed Bragg Reflector (DBR) lasers have emerged as versatile and indispensable tools across various domains. Their advantages, including high signal-to-noise ratios, narrow linewidths, and support for distributed sensing, enable them to excel in diverse applications. DBR lasers have revolutionized optical fiber communication, medical diagnostics, and chaos-based key distribution. They provide precise control over wavelengths, making them valuable in fields such as dermatology, ophthalmology, and photodynamic therapy. Additionally, they play a critical role in flow cytometry, spectroscopy, and dental procedures. In the realm of sensing, DBR lasers have proven their efficacy in detecting parameters like temperature, pressure, current, magnetic fields, and ultrasound. Innovative techniques, such as FPGA-based demodulation and slotted DBR optical fiber lasers, have further enhanced their capabilities. As technology advances, the potential of DBR lasers in sensing and detection applications continues to grow. Their ability to deliver real-time, accurate data across various parameters positions them as essential tools for addressing complex scientific, medical, and industrial challenges. The future promises exciting developments in DBR laser technology, further expanding their role in solving multifaceted problems.

Hybrid distributed Bragg reflector laser on Si with a transfer printed InAs/GaAs quantum dot amplifier.

We demonstrate a hybrid integrated laser by transfer printing an InAs/GaAs quantum dot (QD) amplifier on a Si waveguide with distributed Bragg reflectors (DBRs). The QD waveguide amplifier of 1.6 mm long was patterned in the form of an airbridge with the help of a spin-on-glass sacrificial layer and precisely integrated on the silicon-on-insulator (SOI) waveguide by pick-and-place assembly using an elastomer stamp. Laser oscillation was observed around the wavelength of 1250 nm with a threshold current of 47 mA at room temperature and stable operation up to 80°C. Transfer printing of the long QD amplifiers will enable the development of various hybrid integrated laser devices that leverage superior properties of QDs as laser gain medium.

Multi-Frequency Doppler Velocimetry Based on a Mode-Locked Distributed Bragg Reflector Laser

A differential multi-frequency laser Doppler velocimetry is demonstrated, utilizing the synchronized multimode of a mode-locked distributed Bragg reflector laser. This scheme enables the simultaneous detection of multiple Doppler frequency shifts. Multiple differential Doppler shifts of 0.6 Hz, 1.3 Hz, and 1.9 Hz are obtained, with an average speed of 3.677 mm/s and a standard deviation of 0.122 mm/s, demonstrating a cross-referenced velocity measurement capability. The measurement results are also compared with the dual-frequency laser Doppler velocimetry scheme using electro-optical modulation.

Photonic generation of a tunable multi-band linearly frequency-modulated waveform

A photonic-assisted tunable multi-band linearly frequency-modulated (LFM) waveform generator based on optical heterodyne detection is proposed and experimentally demonstrated. The multi-band LFM waveform is generated from a photodetector (PD), where a broadband LFM optical pulse and a multi-wavelength optical signal with the same magnitude at different wavelengths are heterodyne-detected. The LFM optical pulse is generated from a three-electrode distributed Bragg reflector laser diode (DBR-LD). The multi-wavelength optical signal is produced through a Mach-Zehnder modulator (MZM), in which a light wave from an optical fiber laser (OFL) is nonlinearly intensity-modulated by a radio frequency (RF) signal. By tuning the wavelength of the LFM optical pulse lower than that of the multi-wavelength optical signal, a multi-band LFM waveform is generated at the PD. The center frequency of the generated LFM waveform can be adjusted by manipulating the wavelength of the OFL. The versatility in the bandwidth and temporal duration of the LFM waveform is attained through the precise tuning of the LFM optical pulse. The tuning of the center frequency difference between frequency bands is performed by altering the frequency of the RF signal. Experimental results have corroborated the realization of a tunable multi-band LFM waveform generator. The bandwidth and temporal duration of each band and the center frequency difference between frequency bands have tuning ranges from 0.7 to 6.7 GHz, 1 to 50 μs, and 2 to 6.7 GHz, respectively. The demonstration shows new avenues to implement high-performance multi-band LFM waveform generators for applications in multi-functional modern radar systems.

Single-frequency fiber laser of 315 mW at 1940 nm based on a Tm : YAG/Ho : YAG-co-derived silica fiber.

A 1940 nm single-frequency distributed Bragg reflector (DBR) fiber laser was demonstrated based on a Tm : YAG/Ho : YAG-co-derived silica fiber (THCDSF). The THCDSF, which had a core dopant concentration of 8.02 wt.% Tm2O3 and 1.18 wt.% Ho2O3, was prepared via the melt-in-tube (MIT) method using a Tm : YAG and a Ho : YAG as the precursor core and a silica tube as the cladding. Employing 1.8 cm of the THCDSF, we achieved a maximum single-frequency output power of 315 mW at 1940 nm when pumped by a 1610 nm fiber laser. The slope efficiency of the laser was 29.68% for the absorbed pump power. The laser linewidth was less than 23.65 kHz, and the relative intensity noise (RIN) stabilized at -145 dB/Hz after exceeding 4.8 MHz. To the best of our knowledge, this is the first demonstration of a single-frequency DBR laser with a Tm3+/Ho3+ fiber as the gain medium.

Wide-wavelength-tunable distributed Bragg reflector laser diode with high thermal efficiency.

We proposed a thermally-tuned distributed Bragg reflector (DBR) laser diode that has a high tuning efficiency over a wide wavelength tuning range. The laser diode is composed of a gain, a phase control (PC), and a DBR region, and its wavelength is tuned coarsely and finely by the micro-heaters on the DBR and PC regions, respectively. To improve the tuning efficiency, we developed a technique for fabricating a thermal isolation structure through a reverse mesa etching process, replacing the complex process that uses an InGaAs sacrificial layer. The DBR laser diodes (DBR-LD) fabricated using this method effectively confines heat generated by the heater, resulting in an approximate tuning range of 40 nm. This technology, which has achieved nearly four times larger wavelength tuning range than the thermally-tuned DBR-LDs without a thermal isolation structure, is considered suitable for the cost-effective development of wide-wavelength-tuning DBR-LD light sources.

Distributed Bragg Reflector Laser Based on Composite Fiber Heavily Doped with Erbium Ions

A distributed Bragg reflector (DBR) laser with a specially designed, heavily Er3+-doped composite fiber of a length as short as 1.8 cm is demonstrated. The DBR laser, pumped by a 980 nm laser diode with power of up to 370 mW, generates single-frequency radiation at a wavelength of 1535 nm with a narrow instantaneous linewidth of <100 Hz and a high output power of 2 mW. The obtained Er3+-doped fiber laser parameters pave the way toward a broad range of practical applications from telecommunications and sensing to scientific research.

Surface Vertical Multi-Emission Laser with Distributed Bragg Reflector Feedback from CsPbI3 Quantum Dots.

Quantum dots (QDs) laser has become an important way to solve micro-application problems in many fields. However, single wavelength distributed Bragg reflector (DBR) has many limitations in practical applications, such as signal transmission. How to realize multiwavelength DBR lasing output simply is a challenge. To achieve a stable multi-wavelength quantum dots laser in the near-infrared region, the perovskite CsPbI3 QDs laser with DBR structure is developed in this paper. A tetragonal crystal structure with complete bonding information and no defect is explained by X-ray diffractions (XRD) and Raman spectrum. The cross-section morphology of the DBR laser and the surface morphology of QDs is measured by scanning electron microscope (SEM) and transmission electron microscope (TEM), respectively. An elliptical light propagation field and a double wavelength laser radiation are obtained from the finite-difference time-domain (FDTD) simulation. The output of the three wavelength lasers at 770 nm, 823 nm, and 873 nm is measured. The emission time of a DBR laser is about 2 h, and the average fluorescence quantum yield is 60%. The cavity length selection and energy level model are put in place to clearly see the working mechanism. All the results suggest that an effective and stable CsPbI3 quantum dots DBR laser is realized.

Lasing chirality control of thin-film defect-mode lasers based on cholesteric liquid crystal polymer mirrors

This work investigates the emission chirality of a chiral distributed Bragg reflector (DBR) laser, which is composed by incorporating an isotropic medium containing laser dye between two cholesteric liquid crystal polymer films. The emitted laser showed different ratios of circularly polarized states corresponding to different pitch numbers of the chiral mirror. Through Berreman matrix numerical calculations and experimental results, we validated the variations of the emission chirality coupling in the defect resonance mode as a function of pitch numbers, as well as the effect of the defect layer thickness on the wavelength and mode number of the emitted laser. We also observed the cone-shape emission and examined the threshold of the lasing. The results successfully demonstrated the realization of DBR laser with controllable orthogonal circular polarization ratios in the emitted laser light. These results offer considerable potential for the development of micro-laser sources with different emission chirality and wavelengths for various applications.

A low-magnetic packaging for a distributed Bragg reflector laser diode chip for atomic sensor applications

We implement a distributed Bragg reflector (DBR) laser diode (LD) package with low-magnetic field generation. The package consists of a commercial 795 nm DBR LD chip, a thermo-electric cooler (TEC), a thermistor, a flexible printed circuit board (FPCB) which cancels the magnetic field emitted by the TEC current flow, and a non-magnetic aluminum case. We confirm that the magnetic dipole moment of our low-magnetic package body is about three orders of magnitude smaller than that of a commercial DBR laser package. Moreover, it is shown that our compensating FPCB, the effectiveness of which is supported by computer simulations, reduces the magnetic field magnitude by a factor of 2.2. The FPCB also reduces the magnetic field gradient emitted by the TEC current flow so that gradient-induced spin relaxations are suppressed in applications. A portable optically pumped atomic magnetometer (OPAM) utilizing two low-magnetic packages as light sources is reported as an application of the package and shows a 0.30 pT/Hz1/2 level magnetic sensitivity at a 69 μT external magnetic field; in contrast, the OPAM utilizing the commercial packages showed a magnetic sensitivity of 0.87 pT/Hz1/2.

Monolithically Integrated Tunable Three- Section All-Active DBR Laser Diodes With 30 nm Tuning Range

We present a monolithically integrated three-section all-active AlGaInAs/InP tunable distributed Bragg reflector (DBR) ridge waveguide laser diode that uses thermal tuning mechanism and mode-hopping tuning principle to achieve wide-range wavelength tuning. It is similar to the traditional three-section DBR laser structure, including a gain section, a phase section, and a DBR grating section. The difference is that the phase section and the DBR section incorporate the same active quantum well structure as the gain section. In this case, weak effective refractive index changes of the three active sections affected by the current injection will occur since the carrier density is clamped by the threshold gain condition of the DBR laser diode. Despite this limitation, a noncontinuous tuning up to ∼30 nm (1564–1594 nm) can be observed using only current injection at a constant temperature of 25 °C. Significant thermal effects occurred during the tuning process. In addition, a discontinuity is introduced in the tuning because it does not contain a passive region for phase adjustment. However, the device still provides a stable single longitudinal mode output with nine channels, a wavelength spacing of about 4 nm, and a side mode suppression ratio (SMSR) of more than 30 dB. Furthermore, the DBR laser diode can be easily fabricated utilizing the conventional distributed feedback laser diode fabrication process without secondary epitaxy and heater metal. The all-active DBR laser diode will be expected to be applied in the coarse wavelength division multiplexing (CWDM) systems with the advantage of low cost.

Intra-cavity coherent combining of DBR lasers on an InP generic foundry platform.

We report an intra-cavity coherent combining of two distributed Bragg reflector (DBR) lasers with a combining efficiency of ∼84% on an InP generic foundry platform. The on-chip power of the intra-cavity combined DBR lasers is ∼9.5 mW at the injection current of 42 mA in both gain sections simultaneously. The combined DBR laser operates in a single-mode regime with a side-mode suppression ratio of 38 dB. This monolithic approach paves the way toward high-power and compact lasers, which is useful in scaling integrated photonic technologies.

Accurate Modeling of Distributed Bragg Reflector Laser Power and Wavelength Using Gaussian Process Regression

Distributed Bragg reflector (DBR) lasers are widely used in many physics experiments. However, regarding the power and frequency control of DBR lasers, obtaining complete and accurate output characteristics is challenging due to the need for general and accurate quantitative models. In this study, we propose and validate a method based on Gaussian process regression to quickly and accurately establish the DBR laser output power and wavelength model. Two models are developed to describe the output power, wavelength, input current, and temperature. The findings show that our power model explains the laser’s power change from the current threshold to the maximum value more precisely, with a root mean square error (RMSE) of 0.16921 mW, less than one-fifth of that of the classic power model. Moreover, our wavelength model is feasible for accurately describing the laser wavelength with a RMSE of 4 × 10−4 nm. This study can improve DBR laser power and frequency control efficiency and precision.

Temperature distribution of an SG-DBR laser cooled by a thermoelectric cooler

We introduce a one-dimensional analytical model to determine the steady-state thermal behavior of a sampled grating distributed Bragg reflector laser coupled to a thermoelectric element cooler. The governing equations are a system of ordinary differential equations that can be solved analytically. This method can easily be used when the laser is integrated with more functional elements, e. g., semiconductor optical amplifiers and amplitude modulators. The results are verified by the numerical finite element method and experimental data reported by other researchers. A comparison between the results of the analytical and numerical methods reveals the high consistency between them.

Fiber Bragg Grating Interrogation System Based on the Laser Wavelength Modulation in a Digital Supermode -Distributed Bragg Reflector Laser

In this paper, we propose a Fiber Bragg Grating (FBG) interrogation system based on the modulation of the laser wavelength. Key component of the interrogation scheme is in a Digital Supermode -Distributed Bragg Reflector (DS-DBR) Laser. The DS-DBR features a large spectral range and a fast modulation capability in a low cost device. When the laser spans over the FBG spectral range, the power of the reflected signal changes over time according the FBG spectral shape. The information on the Bragg wavelength can be extracted from the modulated signal reflected by the FBG in the time domain. We implemented the proposed interrogation scheme by discrete components demonstrating its capability to retrieve the Bragg wavelength of one or more FBGs. The interrogation system features an intrinsic tradeoff between spectral resolution and interrogation speed. A Bragg wavelength resolution of 1.5 pm has been obtained using 1 kHz modulating frequency. The proposed interrogation system is particular suited in applications in which an adaptive interrogation strategy can be conveniently adopted.

High Optical Feedback Tolerance of a Detuned DBR Laser for 10-Gbps Isolator-Free Operation

The optical feedback tolerance (OFT) of a distributed Bragg reflector (DBR) laser was investigated experimentally. The static and modulation performance of the DBR laser under optical feedback was examined by evaluating its relative intensity noise (RIN) and bit error rate (BER). It is shown that the OFT of the DBR laser is closely related to its peak wavelength detuning relative to the Bragg wavelength. A high tolerance to optical feedback was demonstrated, both in the continuous wave (CW) and the direct modulation (DM) states, when the DBR laser was red-detuned relative to the Bragg wavelength. The excess RIN induced by optical feedback was well suppressed to a level of −140 dB/Hz at a feedback level of −9 dB in the CW state. In a 10 Gbps direct modulation state, bit error rates (BER) below 1 × 10−9 and 3 × 10−7 were obtained under a feedback level of −15 dB and −9 dB, respectively, for the case of back-to-back transmission. After 20 km fiber transmission, the BER still maintained below 1 × 10−7 under a feedback level of −15 dB, with a power penalty of less than 1 dB.