Laser Diode Driver Research Articles

Laser diode driver on a programmable system on a chip.

A comprehensive solution of a laser diode (LD) driver with temperature control using a programmable system on a chip is proposed as an alternative to dedicated devices. A digital proportional integral differential controller is used for regulating the LD temperature. The light-current characteristics and frequency response of the LD are measured using an external photodiode and interrogated by an integrated transimpedance amplifier. The 0.084% stability, 2kHz bandwidth, and 0.11% full scale current error are demonstrated. The LD overshoot protection is digitally implemented, providing a soft start. While the circuit is initially optimized for a 3W infrared LD, instructions are provided for fine-tuning the design according to specific LD requirements.

A Load-Adaptive Driving Method for a Quasi-Continuous-Wave Laser Diode.

A quasi-continuous-wave (QCW) laser diode (LD) driver is commonly used to drive diode bars and stacks designed specifically for QCW operations in solid-state lasers. Such drivers are optimized to deliver peak current and voltage pulses to LDs while maintaining low average power levels. As a result, they are widely used in laser processing devices and laser instruments. Traditional high-energy QCW LD drivers primarily use capacitors as energy storage components and pulsed constant-current sources with op-amps and power metal-oxide-semiconductor field-effect transistors (MOSFETs) as their core circuits for generating repeated constant-current pulses. The drawback of this type of driver is that the driver's output voltage needs to be manually adjusted according to the operating voltage of the load before use to maximize driver efficiency while providing a sufficient current. Another drawback is its inability to automatically adjust the output voltage to maintain high efficiency when the load changes during the driver operation. Drastic changes in the load can cause the driver to fail to function properly in extreme cases. Based on the above traditional circuit structure, this study designed a stability compensation circuit and realized a QCW LD driver for driving a GS20 diode stack with a maximum repetition rate of 100 Hz, a constant current of approximately 300 A, a load voltage of approximately 10 V, and a pulse width of approximately 300 μs. In particular, a high-efficiency, load-adaptive driving method was used with the MOSFETs in the critical saturation region (i.e., between the linear and saturated regions), controlling its power loss effectively while achieving maximum output current of the driver. The experiments demonstrated that the driver efficiency could be maintained at more than 80% when the load current varied from 50 to 300 A.

Design and Implementation of a Power Semiconductor-Based Switching Mode Laser Diode Driver.

Fiber lasers are commonly used in many industrial applications, such as cutting, welding, marking, and additive manufacturing. In a fiber laser system, the driver of a pumping source using a laser diode (LD) module and its dynamic control capability directly affect the performance of the fiber laser system. The commercial design of pumping source drivers for high-power fiber lasers is mainly based on a linear-type DC power supply, which has two major drawbacks, i.e., lower efficiency and bulk. In this regard, this paper proposes for the first time a new design approach with a programmable switching mode laser diode driver using a power semiconductor device (PSD)-based full-bridge phase-shifted (FB-PS) DC-DC converter for driving a 200 W optical power laser diode module. In this paper, the characteristics of a laser diode module and the system configuration of the proposed laser diode driver are first introduced. Then, a current control scheme using the concept of phase angle shifting to achieve a fast dynamic current tracking feature is explained. The proposed current control technique with a fully digital control scheme is then addressed. Next, dynamic mathematical models of the laser diode driver system and controllers are derived, and the quantitative design detail of the controller is presented. To confirm the correctness of the proposed control scheme, a simulation study on a typical control case is performed in PSIM 9.1 software environment. To verify the effectiveness of the proposed LD driver, a digital signal processor is then used as the control core to construct a hardware prototype implementation for performing experimental tests. Results obtained from simulation and hardware tests show highly satisfactory driving performances in the laser diode's output current command tracking control.

A Low-Cost Measurement Methodology for LiDAR Receiver Integrated Circuits

This paper presents a test methodology to facilitate the measuring processes of LiDAR receiver ICs by avoiding the inherent walk error issue. In a typical LiDAR system, a costly laser diode driver emits narrow light pulses with fast rising edges, and the reflected pulses from targets enter an optical detector followed by an analog front-end (AFE) circuit. Then, the received signals pass through the cascaded amplifiers down to the time-to-digital converter (TDC) that can estimate the detection range. However, this relatively long signal journey leads to the significant decline of rising-edge slopes and the output pulse spreading, thus producing inherent walk errors in LiDAR receiver ICs. Compensation methods requiring complex algorithms and extra chip area have frequently been exploited to lessen the walk errors. In this paper, however, a simpler and lower-cost methodology is proposed to test LiDAR receiver ICs by employing a high-speed buffer and variable delay cells right before the TDC. With these circuits, both START and STOP pulses show very similar pulse shapes, thus effectively avoiding the walk error issue. Additionally, the time interval between two pulses is easily determined by varying the number of the delay cells. Test chips of the proposed receiver IC implemented in a 180-nm CMOS process successfully demonstrate easier and more accurate measurement results.

Compact turnkey system for multi-contact diode lasers for portable spectroscopic applications

Diode laser-based light sources allow the implementation of features to meet specific application requirements. Besides output power and specific wavelength, this can also include spectral tunability, an alternating operation between two different wavelengths, or a well-defined parallel operation at two wavelengths. Potential applications involve spectroscopic systems and applications, e.g., in Raman spectroscopy, especially shifted excitation Raman difference spectroscopy (SERDS) or sequentially shifted Raman spectroscopy, absorption spectroscopy, or the generation of THz radiation. To meet these demands, diode laser based light sources often use a multi-contact layout. Their operation may require multiple individually adjustable current sources, adjustable galvanically isolated current sources, regulated temperature stabilization and heat removal. Moreover, an interface, e.g., a fiber coupling unit is required to transfer the laser light to the experiment. In this paper, a compact turnkey system is reported meeting these requirements with up to 10 current sources, 2 galvanically isolated current sources, integrated temperature control and an interface for laser light transfer is presented. The system has dimensions of 177 mm × 124 mm × 48 mm and is controlled via a standard USB interface. It additionally provides a synchronization signal for implementation into multi-instrument setups. The current sources are based on implemented dual continuous wave p-type laser diode drivers. Ten current sources with 750 mA enabling switching frequencies up to 1000 Hz and four galvanically isolated current sources with 2 W are available. For temperature control, a TEC controller is used. An effective cooling system allows 10 W of thermal load to be removed. The integration of this turnkey-system into a portable shifted excitation Raman difference spectroscopy sensor system is briefly presented as an example application.

Solid-State dToF LiDAR System Using an Eight-Channel Addressable, 20-W/Ch Transmitter, and a 128 × 128 SPAD Receiver With SNR-Based Pixel Binning and Resolution Upscaling

An entire solid-state direct time-of-flight (dToF) light detection and ranging (LiDAR) system that incorporates innovations for both the transmitter (TX) and the receiver (RX) is presented in this work. For the illumination TX, we demonstrate solid-state channel addressability, which significantly reduces the transmit power and improves the ranging distance by dividing the field of view (FoV) into separately illuminated sub-regions. In the RX, we introduce single-photon avalanche diodes (SPADs) pixel binning, which enables reconfigurability of the sensor’s spatial resolution. Finally, we introduce a machine learning (ML) technique that enables this pixel-binned depth sensor to upscale its spatial resolution after training/inference fusion with the intensity image. The laser diode driver (LDD) chip is implemented in the 180-nm bipolar-CMOS-DMOS (BCD) process and is capable of pumping more than 8-A peak current into a multi-junction vertical-cavity surface-emitting laser (VCSEL) array, producing up to 20.3-W optical pulses under 12.5-V supply voltage. The sensor chip is also implemented in the 180-nm BCD process with a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$128 \times 128$ </tex-math></inline-formula> SPAD array and reconfigurable pixel binning. Hardware and software co-optimization under low signal-to-noise ratio (SNR) conditions with ML-based spatial resolution upscaling is demonstrated.

Microcontroller-Based Thermoelectrically Stabilized Laser Diode System

This work aims to describe the development of a prototype laser diode system along with its driver circuit and a stable microcontroller-based thermo-electric cooling system. The laser diode driver circuit was designed and simulated by using NI Multisim. The driver circuit was built using two LM317 ICs to control the voltage across the laser diode and current through the laser diode. The laser diode output power varies by varying the current across the laser diode through the driver circuit. The temperature of the laser diode rises with time, affecting the output power of the laser diode during a long period of operation. A microcontroller-based cooling system was designed and fabricated using thermoelectric coolers. The microcontroller controls the cooling system ON/OFF period to maintain the laser diode at a particular temperature by removing the excess heat produced during the lasing action. The laser diode with a microcontroller-based cooling system shows that the laser diode output power remains stable during a long period of operation.

Optical Trapping of a Single Molecule of Length Sub-1 nm in Solution

Optical Trapping of a Single Molecule of Length Sub-1 nm in Solution

A laser source driver in 0.18 μm SiGe BiCMOS technology for high speed quantum key distribution

Quantum key distribution (QKD) has rapidly developed recently. The repetition frequency of the QKD system increases from tens or hundreds of MHz to GHz. A laser diode (LD) operating in gain-switched mode is widely used as a weak coherent light source in a QKD system. We present an LD driver circuit fabricated in 0.18 μm SiGe heterojunction bipolar transistor bipolar complementary metal oxide semiconductor technology. The circuit can operate at frequencies up to 2.5 GHz, satisfying the requirements of high-speed laser drives in practical QKD systems. The output current of the driver circuit can reach 100 mA when driving an LD whose input equivalent resistance is ∼21 Ω. The extinction ratio of the 1550-nm distributed feedback LD light source driven by our driver circuit reaches 23 dB at the operating frequency of 2.5 GHz, meeting the requirements of QKD systems. This circuit will be used in miniaturized QKD systems.

An 8-A Sub-1ns Pulsed VCSEL Driver IC With Built-In Pulse Monitor and Automatic Peak Current Control for Direct Time-of-Flight Applications

An integrated laser diode driver for multi-junction vertical-cavity surface-emitting laser (VCSEL) arrays is presented in this brief. The driver chip, fabricated in 180nm bipolar-CMOS-DMOS (BCD) process, working under 12V supply, can pump more than 8A peak current into a triple-junction VCSEL array, producing up to 20.3W optical pulses. Measured optical pulses have tunable widths from 276ps to 2352ps with 120ps/160ps rise/fall time. When emitting 10MHz-frequency 960ps-width optical pulses with peak power ranging from 3.6W to 17.5W, the driver-VCSEL system has over 20% electrical-to-optical power conversion efficiency. The driver can record its output current waveform with a built-in pulse monitor. The peak data from the recorded waveform is used for automatic peak current control.

MULTIELEMENT LASER’S PUMP CURRENT FRONT SHAPING METHOD

It is shown that for reliable operation of laser diode matrices, it is important to ensure the maximum allowable, but not leading to their destruction, current input and output rate. Some of the solutions used in the design of laser diode drivers are listed in order to limit the increase in the rate of current input and output.&#x0D; A method for controlling the rate of rise of the laser emitter current is proposed, the essence of which is to form the leading and trailing edges of the output current of the laser driver so that its first and, at least, the second derivative are continuous, in order to avoid triggering internal mechanisms that lead to degradation of the emitter structure.

Design of High Peak Power Pulsed Laser Diode Driver

This paper attempts to describe a laser diode driver circuit using the depletion mode gallium nitride high electron mobility transistor (D-mode GaN HEMT) to generate nanosecond pulses at a repetition rate up to 10 MHz from the vertical-cavity surface-emitting laser (VCSEL). The feature of this driver circuit is a large instantaneous laser power output designed in the most efficient way. The design specifications include a pulse duration between 10 ns and 100 ns and a peak power up to above 100 W. The pulsed laser diode driver uses the D-mode GaN HEMT, which has very small Coss difference between turn-on and turn-off states. The analysis is according to a laser diode model that is adjusted to match the VCSEL, made in National Yang Ming Chiao Tung University (NYCU). A design guide is summarized from the derivations and analysis of the proposed laser diode driver. According to the design guide, we selected the capacitor, resistor, and diode components to achieve 10 ns to 100 ns pulse duration for laser lighting. The experiment demonstrated that the maximum power-to-light efficiency can be as high as 86% and the maximum peak power can be 150 W, which matches the specifications of certain applications such as light detection and ranging (LiDAR).

Low-cost electronic circuitry for photoacoustic gas sensing

The circuitry comprises a sine wave generator based on direct digital synthesis, a laser diode driver module, a band-pass frequency filter, a synchronous detector with phase adjustment circuitry and a low pass filter to form an analog lock-in amplifier, and an analog-to-digital converter. A 32-bit ARM microcontroller programmed with the open source Mecrisp dialect of the Forth interpreter language is used to set the frequency, and read the data from the analog-to-digital converter. The circuitry is tethered via a serial interface to a personal computer. A graphical user interface written in Phython allows easy interaction with the microcontroller by sending the appropriate Forth commands. The data acquired is visualized and stored on the personal computer for further processing. The circuitry is easy to build as it is based on through-hole devices, except for two necessary surface mount items, which, however, still can be soldered with a fine tipped soldering iron. The performance of the circuitry was demonstrated by the photoacoustic detection of NO2 using a laser diode with a wavelength of 450 nm.

A 15 Gbps-NRZ, 30 Gbps-PAM4, 120 mA laser diode driver implemented in 0.15-µm GaAs E-mode pHEMT technology

This paper presents the design and testing of a 15 Gbps non-return-to-zero (NRZ), 30 Gbps 4-level pulse amplitude modulation (PAM4) configurable laser diode driver (LDD) implemented in 0.15-µm GaAs E-mode pHEMT technology. The driver bandwidth is enhanced by utilizing cross-coupled neutralization capacitors across the output stage. The output transmission-line back-termination, which absorbs signal reflections from the imperfectly matched load, is performed passively with on-chip 50-Ω resistors. The proposed 30 Gbps PAM4 LDD is implemented by combining two 15 Gbps-NRZ LDDs, as the high and low amplification paths, to generate PAM4 output current signal with levels of 0, 40, 80, and 120 mA when driving 25-Ω lasers. The high and low amplification paths can be used separately or simultaneously as a 15 Gbps-NRZ LDD. The measurement results show clear output eye diagrams at speeds of up to 15 and 30 Gbps for the NRZ and PAM4 drivers, respectively. At a maximum output current of 120 mA, the driver consumes 1.228 W from a single supply voltage of –5.2 V. The proposed driver shows a high current driving capability with a better output power to power dissipation ratio, which makes it suitable for driving high current distributed feedback (DFB) lasers. The chip occupies a total area of 0.7 × 1.3 mm2.

Design of integrated laser diode driver for 3D-depth sensing applications

This paper presents the design and comparison of two integrated CMOS Laser Diode Drivers (LDD) intended for 3D-depth sensing applications used in mobile phones and based on the indirect Time-of-Flight (iToF) measurement. Architectures are based on known driver topologies where a standard DC/DC converter is connected to a switching element either in series or parallel to provide pulses. Two LDD prototypes have been implemented on-chip using a 130 nm CMOS technology from STMicroelectronics. Both prototypes are able to generate current pulses up to 3A with a 2.5ns pulse width at a maximum 200 MHz Pulse Repetition Frequency (PRF) under a 3.6V supply voltage. In these conditions, measurement results report an average output electrical power of 4.5W with an electrical efficiency of 58% and 62% for series and shunt configuration respectively.

A 50 Gb/s PAM‐4 VCSEL diode driver in 90 nm CMOS technology

AbstractIn this article, a broadband vertical cavity surface emitting laser (VCSEL) diode driver circuit has been implemented in TSMC 90‐nm complementary metal‐oxide‐semiconductor technology. The laser diode driver (LDD) circuit includes a pre‐amplifier, a post‐amplifier paralleling with a differentiator, and a current steering circuit. The input to the LDD can be two 25 Gb/s nonreturn to zero voltage signals, which can thereby generate a 50 Gb/s four‐level pulse amplitude modulation (PAM‐4) current signal to drive a VCSEL diode. Using the LDD chip on a printed circuit board, clear PAM‐4 eye diagrams corresponding to 25, 40, and 50 Gb/s can be measured to verify the performance of the LDD chip. The VCSEL LDD chip has been applied in the optical transmitter for short‐reach transmissions.

2ch × 53-Gbps Optical Transmission Performance of a Low-Power PAM4 Transmitter Front-End Flip-Chip-Bonded 1.3-μm LD Array-on-Si

This article presents a 2-channel 4-level pulse amplitude modulation (PAM4) transmitter front-end consisting of a 2-channel PAM4 shunt laser diode (LD) driver and flip-chip-bonded 1.3-μm LD array-on-Si that has the highest power efficiency yet reported for PAM4 transmitter front-ends. The driver was designed and fabricated using 65-nm CMOS technology, and the LD array-on-Si was fabricated using 1.3-μm membrane LD array-on-Si technology. To decrease the power consumption, the front-end does not use a high-speed digital-to-analog converter (DAC) or linear driver for generating the PAM4 signals. Instead, to generate clear PAM4 signals, the shunt LD driver incorporates DAC, and equalizing functions. The driver was designed with a photonic-electronic conversion system in SPICE, and the transmitter front-end was implemented with flip-chip-bonding interconnection between the driver and LD array-on-Si. The resulting 2-channel PAM4 transmitter front-end has high power efficiency. Our experiments show that in simultaneous operation, each channel could transmit 53-Gbps PAM4 signals, resulting in a power efficiency of 0.57 mW/Gbps. They also show that feed-forward equalization (FFE) with only 10 taps is enough for 2-km-long standard single-mode fiber (SSMF) transmission of 53-Gbps PAM4 signals with a bit error rate (BER) below 2.3 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-4</sup> when the two channels are operated simultaneously.

Three-channel Laser Diode Driver for Multimedia Laser Projectors

The paper describes the design, implementation andtest results of a three-channel laser diode driver intended for use inmultimedia laser projectors. Our development goals were to create acompact and power-efficient driver, which achieves good colormixing and supports high modulation frequencies. It is compatiblewith most laser diode configurations used in multimedia laserprojectors with a total optical output power of several watts. Thedriver is equipped with three protected signal modulation inputs. Itneeds a single regulated power supply between 9V and 18V andcontrols up to three cooling fans intended for the thermalmanagement of the laser diodes. Our initial tests show that the driverworks very well and is suitable for the long-term operation inprojector systems. In the future, we plan to perform more tests on thesignal feedback for various input signal combinations, which shouldresult in optimizations of the feedback configuration andimprovements of the modulation response of the driver.

Asymmetric slope compensation for digital hybrid current mode control of a three-level flying capacitor buck converter

The three-level flying capacitor (3LFC) buck converter has the potential to provide better efficiency and higher power density as compared to the traditional buck converter. However, due to the flying capacitor?s instability issues, control is challenging. In this paper, the digital hybrid current mode (DHCM) control method, which combines the average and peak current mode control techniques, is modified and implemented to a 3LFC buck converter. For flying capacitor (FC) voltage balancing, a novel asymmetric slope compensation (ASC) technique is presented. The proposed ASC technique achieves FC voltage balancing by adjusting the slope compensation of the two switching pairs asymmetrically, and therefore is applicable to any type of digital peak current mode control (PCM) method. The ASC technique for DHCM control of the 3LFC buck converter is verified in simulations and experimentally with an ARMbased mixed-signal microcontroller on a 250-kHz, 24-V input, and 35-W/4-A output prototype. The overall control method enables the implementation of the 3LFC buck converter for accurate and fast current regulation, and therefore is especially advantageous for LED and laser diode driver applications.

Integrated electronics in 130 nm CMOS process for quantum key distribution sender device.

Quantum Key Distribution (QKD) is the most mature method for implementing commercial quantum communications in practice. As part of the miniaturization of practical QKD devices, an integrated electronic system in the 130 nm complementary metal oxide semiconductor process is presented for the QKD sender device. The electronics provide driving signals for the optics at the sender terminal of the quantum channel in QKD and consist mainly of three key modules, namely, a laser diode driver with a high slew rate, a high-speed physical random number generator, and a pre-driver for the electro-optic modulator. The electronic system is designed to operate at frequencies as high as 625-MHz to accommodate the frequency of the QKD system. The high degree of integration is advantageous for miniaturizing QKD sender devices.