rus
Issue #5/2021
V. P. Duraev, S. A. Voronchenko, I. S. Molodtsov
Tunable Single-Frequency Semiconductor Laser Module Based on Two-Pass 1550 nm Wavelength Amplifier
Tunable Single-Frequency Semiconductor Laser Module Based on Two-Pass 1550 nm Wavelength Amplifier
DOI: 10.22184/1993-7296.FRos.2021.15.5.410.418
The results of work on the creation of tunable single-frequency semiconductor laser modules for a wavelength of 1550 nm with an external cavity based on fiber Bragg gratings (FBGs) formed in a single-mode fiber are presented. The methods for discrete and smooth tuning of the radiation wavelength are considered. The presented laser modules are capable of generating dynamically stable single-frequency radiation with a side mode suppression of more than 40 dB, a lasing line width of 100–500 kHz, and an output optical power of more than 35 mW. The wavelength tuning of the radiation spectrum of the laser module was 1.5 nm.
The results of work on the creation of tunable single-frequency semiconductor laser modules for a wavelength of 1550 nm with an external cavity based on fiber Bragg gratings (FBGs) formed in a single-mode fiber are presented. The methods for discrete and smooth tuning of the radiation wavelength are considered. The presented laser modules are capable of generating dynamically stable single-frequency radiation with a side mode suppression of more than 40 dB, a lasing line width of 100–500 kHz, and an output optical power of more than 35 mW. The wavelength tuning of the radiation spectrum of the laser module was 1.5 nm.
Теги: fiber bragg gratings single-frequency tunable laser tuning of the radiation wavelength волоконные брэгговские решетки одночастотный перестраиваемый лазер перестройка длины волны излучения
Tunable Single-Frequency Semiconductor Laser Module Based on Two-Pass 1550 nm Wavelength Amplifier
V. P. Duraev, S. A. Voronchenko, I. S. Molodtsov
Nolatech JSC, Moscow, Russia
The results of work on the creation of tunable single-frequency semiconductor laser modules for a wavelength of 1550 nm with an external cavity based on fiber Bragg gratings (FBGs) formed in a single-mode fiber are presented. The methods for discrete and smooth tuning of the radiation wavelength are considered. The presented laser modules are capable of generating dynamically stable single-frequency radiation with a side mode suppression of more than 40 dB, a lasing line width of 100–500 kHz, and an output optical power of more than 35 mW. The wavelength tuning of the radiation spectrum of the laser module was 1.5 nm.
Keywords: single-frequency tunable laser, tuning of the radiation wavelength, fiber Bragg gratings.
Received on: 09.08.2021
Accepted on: 25.08.2021
INTRODUCTION
In the last 20 years, injection lasers have entered the period of their widespread use. The compactness, speed, efficiency and simplicity of the device are realized in such important applications as fiber-optic communications, memory systems, etc. At the same time, physical research and new developments aimed at identifying and using the limiting capabilities of lasers to meet higher requirements are relevant.
The ability to isolate one frequency and its smooth tuning have made it possible to find applications in various fields of scientific research, such as: high-resolution spectroscopy, analytical spectroscopy and, in particular, the detection of atmospheric pollution, measuring interferometry, sensors, in various scientific instrumentation and medical diagnostics equipment, optical pumping lasers based on crystals and glasses doped with rare-earth ions, primarily neodymium, ytterbium and erbium [1]. The possibility of using tunable single-frequency semiconductor lasers as a seed radiation source for single-frequency pulsed solid-state ND : YAG lasers with a line width of less than 100 MHz was also demonstrated. [2].
CREATION OF A LASER MODULE
At the first stage of the development of semiconductor tunable lasers, laser diodes (LDs) with a short cavity (100–200 µm) were used. Taking into account that the free spectral range for such emitters is large, the difference in the amplification of neighboring modes reaches a significant value. As a result, the emission spectrum of short-cavity lasers usually has one longitudinal mode. The wavelength of such lasers was tuned by changing the temperature and pump current. The disadvantages of such lasers were their low output power, large emission line width (100 MHz), and unstable operation.
Distributed feedback (DFB) semiconductor laser with dynamic single longitudinal mode has become the first choice as a light source for fiber optic communication, which has made it popular in the field of single frequency semiconductor lasers. In this type of single-frequency lasers, the diffraction grating is integrated into the cavity of the laser diode. This class of lasers has a more stable single-frequency mode of operation, a relatively low optical power and a radiation linewidth of the order of 1–10 MHz [3]. Wavelength tuning is performed by changing the laser temperature or pump current [4].
For single frequency semiconductor lasers, stability and linewidth are critical. The stability and linewidth in the free-running laser mode is influenced by many parameters, including frequency noise. The source of frequency noise is mainly spontaneous emission. In addition, a change in the stationary number of photons due to spontaneous emission causes a corresponding change in the gain, i. e. the concentration of electrons, which in turn leads to a change in the refractive index and generation frequency. Together with the number of carriers, both the electric current and the degree of heating of the substance itself fluctuate. [5]. As a result, even in single-frequency DFB and distributed Bragg reflectors (DBR) lasers, it is not possible to obtain a lasing line width of less than 1 MHz.
External cavity lasers are used to suppress the frequency noise that appears in the free-running mode and further narrow the generation line. An antireflection coating is applied to the output face of the active element, thereby excluding this face from the formation of the geometry of the laser resonator. A wavelength-selective element, as a rule, is a diffraction or Bragg grating, acts as a “deaf” mirror. The positive feedback created in this way will generate photons of the frequency to which the selective element is tuned. Continuous tuning range and accuracy are dependent on optics design and associated mechanics.
An alternative to lasers with an external diffraction grating is an FBG laser, where the FBG plays the role of an external frequency-selective element [6–8]. This approach is simpler and more reliable, as it eliminates the presence of many moving components. In fig. 1 shows the block diagram of the module. The main design elements are: a two-pass amplifier (1) with a 90% reflective coating on the back face of the resonator and an antireflection coating of the front face of 0.01%, as well as a beveled waveguide to the output face at an angle of 8˚; a Bragg grating (2) formed in the fiber core; a cylindrical microlens (3) formed at the end of the fiber, providing radiation input into the optical fiber of more than 80%; an optical isolator (4) and piezoceramic (5), on which an optical fiber with an FBG is rigidly fixed.
The distance from the output face of the active element to the FBG is 10 mm. This limitation is due to the peculiarities of the technology of optical fiber attachment, optical fiber alignment relative to the active element, and FBG attachment to piezoelectric ceramics. If you do not use piezoelectric ceramics and refuse the possibility of tuning, then this distance can be reduced to 3–5 mm.
The FBGs used in this research were manufactured by LIKoptika LLC using the phase mask method. The spectral width of the FBG was chosen to be minimal (0.08 nm) in order to exclude the penetration of neighboring laser modes inside the selectivity of the FBG. The FBG parameters are given in Table 1.
Wavelength tuning of wavelength is carried out according to Bragg’s law:
λB = 2 neff Λ ,
where the Bragg grating wavelength λB is the central Bragg wavelength that will be reflected back from the Bragg grating, and neff is the effective refractive index of the fiber core at the central wavelength, Λ is the grating period.
The Bragg wavelength depends on the effective refractive index of the fiber core and on the grating period, which are affected by temperature changes and strains.
We used epitaxial structures based on InAlGaAs / lnP (emission wavelength 1300–1650 nm) with quantum-well layers fabricated by Metalorganic Vapor Phase Epitaxy. The structures were manufactured by M. F. Stelmakh Research Institute “Polyus” JSC. The active element is made on the basis of a ridge waveguide. The cavity length of the double-pass amplifier was 1 mm.
In our research, we used a piezoceramic element based on the inverse piezoelectric effect, manufactured by Research Institute “Elpa” JSC. A fiber with an FBG is rigidly fixed to the piezoceramics. Under tension-compression of piezoceramics, the FBG period changes, which leads to a change in the Bragg resonant wavelength. Following Table 2 shows the characteristics of piezoelectric ceramics used in this research.
All elements of the laser module are placed in a unified 14 pin DIL “Butterfly” case. Fig. 2a shows a simplified model of the placement of all the constituent elements in the body, and Fig. 2b shows the finished laser module with driver board.
PERFORMANCE MEASUREMENT
AND DISCUSSION
To measure the watt-ampere (WAC) and current-voltage characteristics (VAC) of a tunable single-frequency semiconductor laser module, a stand is used, the block diagram of which is shown in Fig. 3.
The LD temperature controller allows you to control and change the temperature of the thermoelectric microcooler (TEMC), on which the two-pass amplifier is located. This circuit is made on the basis of the DLC‑1300 driver manufactured by NOLATEH JSC.
Fig. 4 below shows the VAC and WAC characteristics of a tunable single-frequency semiconductor laser module based on a two-pass amplifier.
With an increase in the pump current, the active region of the two-pass amplifier heats up due to Joule heating, which causes a shift of the longitudinal mode of the two-pass amplifier between the two modes of the external cavity. This introduces instability into the single-frequency lasing regime with the appearance of a mode hopping. On the graph of the watt-ampere characteristic, this looks like a kink in the curve. Then, a stable single-frequency laser operation is observed until the next hop. Since the influence of the internal resonator is maximally suppressed in a two-pass amplifier, the mode hopping is not so pronounced as compared to an active element having a straight stripe. The characteristics of a tunable single-frequency semiconductor laser module are given in Table 3.
Fig. 5 shows the watt-ampere characteristics of a tunable single-frequency semiconductor lasers at different values of the temperature of the active element. An increase in temperature leads to a large drop in power output. The strong temperature dependence of the output optical power is explained by a decrease in the gain with increasing temperature. An increase in temperature leads to an increase in nonradiative processes, the dominant of which is Auger recombination. A strong temperature dependence is typical for lasers in the 1300–1650 nm wavelength range.
An AQ6317 optical spectrum analyzer (Ando, Japan) was used to study the spectral characteristics of tunable single-frequency semiconductor lasers. Measurement of wavelength and analysis of the optical spectrum of radiation is carried out in the range 600–1700 nm. Resolution 0.01 nm. On a logarithmic scale, side mode suppression was observed to be 40–45 dB. The emission spectrum is shown in Fig. 6.
The lasing linewidth was ~ 10–100 kHz; this effect of a radical narrowing of the emission linewidth of a tunable single-particle laser module was investigated at the Fiber Technology Research Center at the GPI of RAS using a Mach-Zehnder fiber interferometer. [9]
Fig. 7 shows the dependence of the wavelength of the laser module on the voltage on the piezoelectric ceramics (FBG stretching). Since the dependence of the stretching of the piezoelectric ceramics on the voltage applied to it is a hesteresis loop, the dependence of the shift of the lasing wavelength on the stretching of the piezoelectric ceramics also has a hesteresis loop. The tuning step is 0.04 nm, which is the intermode distance for the external cavity formed by the FBG and a two-pass amplifier. There is no influence of the internal resonator on the quality of the tuning curve. Wavelength tuning occurs according to the red and blue graphs.
Continuous tuning of the laser module wavelength can be performed by modulating the pump current or the temperature of the active element [10]. In this case, the tuning range is strictly limited by the FBG selectivity of 0.08 nm.
CONCLUSIONS
Thus, a tunable single-frequency semiconductor laser module based on a two-pass amplifier, emitting at a wavelength of 1550 nm, was created. Their main design and operational characteristics are presented. The radiation power at the output of the optical fiber is 35 mW. The linewidth of the laser module in the single-particle mode is 100–500 kHz and is tunable in the range of 1–1.5 nm. The operational life is 100 thousand hours.
REFERENCES
Zujie Fang, Haiwen Cai, Gaoting Chen, Ronghui Qu. Single Frequency Semiconductor Lasers. – Springer Singapore. 2017. 306 p.
Bogdanovich M. V. et al. Transversely diode-pumped -switched Nd : YAG laser with injection of radiation from a single-frequency semiconductor laser. Quantum Electronics. 2016; 46(10): 870–872. URL:[http://mi.mathnet.ru/rus/qe/v46/i10/p870].
Spencer J. E., Young P. Contrasting the Photodigm DBR Laser Diode Architecture with Competing DFB Designs. Photonics Russia. 2018;70(2):166–173. DOI: 10.22184/1993–7296.2018.70.2.166.173.
Bagaeva O. O. et al. Experimental studies of 1.5–1.6 μm high-power single-frequency semiconductor lasers. Quantum Electronics. 2020;50(2): 143–146. URL: [http://dx.doi.org/10.1070/QEL17183].
Kamiya T., Ocu M., YAmamoto V. Fizika poluprovodnikovyh lazerov / red. H. Takumy. – M.: Mir. 1989. 310 p. [in Russ.]
Lynch S. G. et al. Bragg-grating-stabilized external cavity lasers for gas sensing using tunable diode laser spectroscopy. Novel In-Plane Semiconductor Lasers XIII. – International Society for Optics and Photonics. 2014; 9002: 900209.
Lynch S. G. et al. External cavity diode laser based upon an FBG in an integrated optical fiber platform. Optics express. 2016; 24(8): 8391–8398.
Juodawlkis P. W. et al. High-power ultralow-noise semiconductor external cavity lasers based on low-confinement optical waveguide gain media. Novel In-Plane Semiconductor Lasers IX. – International Society for Optics and Photonics. 2010; 7616: 76160X.
Belovolov M. I., Dianov E. M., Duraev V. P. et al. Poluprovodnikovye lazery s gibridnym rezonatorom na volokonnyh breggovskih reshetkah. – M.: IOFAN. 2002. 67 p.
Duraev V., Medvedev S. Single-Frequency Semiconductor Lasers Based on Two-Pass Amplifiers. Fotonika. 2015; 9(6):54–61. URL: [www.photonics.su/journal/article/4987].
ABOUT AUTHORS
Duraev V. P., Doctor of Technical Sciences, JSC “New Laser Technology”,
http://nolatech.ru, Moscow, Russia.
ORCID:0000-0002-2701-0335
Voronchenko S. A., JSC “New Laser Technology”, http://nolatech.ru, Moscow, Russia.
ORCID: 0000-0002-3913-1097
Molodtsov I.S., JSC “New Laser Technology”, http://nolatech.ru, Moscow, Russia.
Contribution by the members of the team of authors
The article was prepared on the basis of many years of work by all members of the team of authors.
Conflict of interest
The authors claim that they have no conflict of interest. All authors took part in writing the article and supplemented the manuscript in part of their work.
V. P. Duraev, S. A. Voronchenko, I. S. Molodtsov
Nolatech JSC, Moscow, Russia
The results of work on the creation of tunable single-frequency semiconductor laser modules for a wavelength of 1550 nm with an external cavity based on fiber Bragg gratings (FBGs) formed in a single-mode fiber are presented. The methods for discrete and smooth tuning of the radiation wavelength are considered. The presented laser modules are capable of generating dynamically stable single-frequency radiation with a side mode suppression of more than 40 dB, a lasing line width of 100–500 kHz, and an output optical power of more than 35 mW. The wavelength tuning of the radiation spectrum of the laser module was 1.5 nm.
Keywords: single-frequency tunable laser, tuning of the radiation wavelength, fiber Bragg gratings.
Received on: 09.08.2021
Accepted on: 25.08.2021
INTRODUCTION
In the last 20 years, injection lasers have entered the period of their widespread use. The compactness, speed, efficiency and simplicity of the device are realized in such important applications as fiber-optic communications, memory systems, etc. At the same time, physical research and new developments aimed at identifying and using the limiting capabilities of lasers to meet higher requirements are relevant.
The ability to isolate one frequency and its smooth tuning have made it possible to find applications in various fields of scientific research, such as: high-resolution spectroscopy, analytical spectroscopy and, in particular, the detection of atmospheric pollution, measuring interferometry, sensors, in various scientific instrumentation and medical diagnostics equipment, optical pumping lasers based on crystals and glasses doped with rare-earth ions, primarily neodymium, ytterbium and erbium [1]. The possibility of using tunable single-frequency semiconductor lasers as a seed radiation source for single-frequency pulsed solid-state ND : YAG lasers with a line width of less than 100 MHz was also demonstrated. [2].
CREATION OF A LASER MODULE
At the first stage of the development of semiconductor tunable lasers, laser diodes (LDs) with a short cavity (100–200 µm) were used. Taking into account that the free spectral range for such emitters is large, the difference in the amplification of neighboring modes reaches a significant value. As a result, the emission spectrum of short-cavity lasers usually has one longitudinal mode. The wavelength of such lasers was tuned by changing the temperature and pump current. The disadvantages of such lasers were their low output power, large emission line width (100 MHz), and unstable operation.
Distributed feedback (DFB) semiconductor laser with dynamic single longitudinal mode has become the first choice as a light source for fiber optic communication, which has made it popular in the field of single frequency semiconductor lasers. In this type of single-frequency lasers, the diffraction grating is integrated into the cavity of the laser diode. This class of lasers has a more stable single-frequency mode of operation, a relatively low optical power and a radiation linewidth of the order of 1–10 MHz [3]. Wavelength tuning is performed by changing the laser temperature or pump current [4].
For single frequency semiconductor lasers, stability and linewidth are critical. The stability and linewidth in the free-running laser mode is influenced by many parameters, including frequency noise. The source of frequency noise is mainly spontaneous emission. In addition, a change in the stationary number of photons due to spontaneous emission causes a corresponding change in the gain, i. e. the concentration of electrons, which in turn leads to a change in the refractive index and generation frequency. Together with the number of carriers, both the electric current and the degree of heating of the substance itself fluctuate. [5]. As a result, even in single-frequency DFB and distributed Bragg reflectors (DBR) lasers, it is not possible to obtain a lasing line width of less than 1 MHz.
External cavity lasers are used to suppress the frequency noise that appears in the free-running mode and further narrow the generation line. An antireflection coating is applied to the output face of the active element, thereby excluding this face from the formation of the geometry of the laser resonator. A wavelength-selective element, as a rule, is a diffraction or Bragg grating, acts as a “deaf” mirror. The positive feedback created in this way will generate photons of the frequency to which the selective element is tuned. Continuous tuning range and accuracy are dependent on optics design and associated mechanics.
An alternative to lasers with an external diffraction grating is an FBG laser, where the FBG plays the role of an external frequency-selective element [6–8]. This approach is simpler and more reliable, as it eliminates the presence of many moving components. In fig. 1 shows the block diagram of the module. The main design elements are: a two-pass amplifier (1) with a 90% reflective coating on the back face of the resonator and an antireflection coating of the front face of 0.01%, as well as a beveled waveguide to the output face at an angle of 8˚; a Bragg grating (2) formed in the fiber core; a cylindrical microlens (3) formed at the end of the fiber, providing radiation input into the optical fiber of more than 80%; an optical isolator (4) and piezoceramic (5), on which an optical fiber with an FBG is rigidly fixed.
The distance from the output face of the active element to the FBG is 10 mm. This limitation is due to the peculiarities of the technology of optical fiber attachment, optical fiber alignment relative to the active element, and FBG attachment to piezoelectric ceramics. If you do not use piezoelectric ceramics and refuse the possibility of tuning, then this distance can be reduced to 3–5 mm.
The FBGs used in this research were manufactured by LIKoptika LLC using the phase mask method. The spectral width of the FBG was chosen to be minimal (0.08 nm) in order to exclude the penetration of neighboring laser modes inside the selectivity of the FBG. The FBG parameters are given in Table 1.
Wavelength tuning of wavelength is carried out according to Bragg’s law:
λB = 2 neff Λ ,
where the Bragg grating wavelength λB is the central Bragg wavelength that will be reflected back from the Bragg grating, and neff is the effective refractive index of the fiber core at the central wavelength, Λ is the grating period.
The Bragg wavelength depends on the effective refractive index of the fiber core and on the grating period, which are affected by temperature changes and strains.
We used epitaxial structures based on InAlGaAs / lnP (emission wavelength 1300–1650 nm) with quantum-well layers fabricated by Metalorganic Vapor Phase Epitaxy. The structures were manufactured by M. F. Stelmakh Research Institute “Polyus” JSC. The active element is made on the basis of a ridge waveguide. The cavity length of the double-pass amplifier was 1 mm.
In our research, we used a piezoceramic element based on the inverse piezoelectric effect, manufactured by Research Institute “Elpa” JSC. A fiber with an FBG is rigidly fixed to the piezoceramics. Under tension-compression of piezoceramics, the FBG period changes, which leads to a change in the Bragg resonant wavelength. Following Table 2 shows the characteristics of piezoelectric ceramics used in this research.
All elements of the laser module are placed in a unified 14 pin DIL “Butterfly” case. Fig. 2a shows a simplified model of the placement of all the constituent elements in the body, and Fig. 2b shows the finished laser module with driver board.
PERFORMANCE MEASUREMENT
AND DISCUSSION
To measure the watt-ampere (WAC) and current-voltage characteristics (VAC) of a tunable single-frequency semiconductor laser module, a stand is used, the block diagram of which is shown in Fig. 3.
The LD temperature controller allows you to control and change the temperature of the thermoelectric microcooler (TEMC), on which the two-pass amplifier is located. This circuit is made on the basis of the DLC‑1300 driver manufactured by NOLATEH JSC.
Fig. 4 below shows the VAC and WAC characteristics of a tunable single-frequency semiconductor laser module based on a two-pass amplifier.
With an increase in the pump current, the active region of the two-pass amplifier heats up due to Joule heating, which causes a shift of the longitudinal mode of the two-pass amplifier between the two modes of the external cavity. This introduces instability into the single-frequency lasing regime with the appearance of a mode hopping. On the graph of the watt-ampere characteristic, this looks like a kink in the curve. Then, a stable single-frequency laser operation is observed until the next hop. Since the influence of the internal resonator is maximally suppressed in a two-pass amplifier, the mode hopping is not so pronounced as compared to an active element having a straight stripe. The characteristics of a tunable single-frequency semiconductor laser module are given in Table 3.
Fig. 5 shows the watt-ampere characteristics of a tunable single-frequency semiconductor lasers at different values of the temperature of the active element. An increase in temperature leads to a large drop in power output. The strong temperature dependence of the output optical power is explained by a decrease in the gain with increasing temperature. An increase in temperature leads to an increase in nonradiative processes, the dominant of which is Auger recombination. A strong temperature dependence is typical for lasers in the 1300–1650 nm wavelength range.
An AQ6317 optical spectrum analyzer (Ando, Japan) was used to study the spectral characteristics of tunable single-frequency semiconductor lasers. Measurement of wavelength and analysis of the optical spectrum of radiation is carried out in the range 600–1700 nm. Resolution 0.01 nm. On a logarithmic scale, side mode suppression was observed to be 40–45 dB. The emission spectrum is shown in Fig. 6.
The lasing linewidth was ~ 10–100 kHz; this effect of a radical narrowing of the emission linewidth of a tunable single-particle laser module was investigated at the Fiber Technology Research Center at the GPI of RAS using a Mach-Zehnder fiber interferometer. [9]
Fig. 7 shows the dependence of the wavelength of the laser module on the voltage on the piezoelectric ceramics (FBG stretching). Since the dependence of the stretching of the piezoelectric ceramics on the voltage applied to it is a hesteresis loop, the dependence of the shift of the lasing wavelength on the stretching of the piezoelectric ceramics also has a hesteresis loop. The tuning step is 0.04 nm, which is the intermode distance for the external cavity formed by the FBG and a two-pass amplifier. There is no influence of the internal resonator on the quality of the tuning curve. Wavelength tuning occurs according to the red and blue graphs.
Continuous tuning of the laser module wavelength can be performed by modulating the pump current or the temperature of the active element [10]. In this case, the tuning range is strictly limited by the FBG selectivity of 0.08 nm.
CONCLUSIONS
Thus, a tunable single-frequency semiconductor laser module based on a two-pass amplifier, emitting at a wavelength of 1550 nm, was created. Their main design and operational characteristics are presented. The radiation power at the output of the optical fiber is 35 mW. The linewidth of the laser module in the single-particle mode is 100–500 kHz and is tunable in the range of 1–1.5 nm. The operational life is 100 thousand hours.
REFERENCES
Zujie Fang, Haiwen Cai, Gaoting Chen, Ronghui Qu. Single Frequency Semiconductor Lasers. – Springer Singapore. 2017. 306 p.
Bogdanovich M. V. et al. Transversely diode-pumped -switched Nd : YAG laser with injection of radiation from a single-frequency semiconductor laser. Quantum Electronics. 2016; 46(10): 870–872. URL:[http://mi.mathnet.ru/rus/qe/v46/i10/p870].
Spencer J. E., Young P. Contrasting the Photodigm DBR Laser Diode Architecture with Competing DFB Designs. Photonics Russia. 2018;70(2):166–173. DOI: 10.22184/1993–7296.2018.70.2.166.173.
Bagaeva O. O. et al. Experimental studies of 1.5–1.6 μm high-power single-frequency semiconductor lasers. Quantum Electronics. 2020;50(2): 143–146. URL: [http://dx.doi.org/10.1070/QEL17183].
Kamiya T., Ocu M., YAmamoto V. Fizika poluprovodnikovyh lazerov / red. H. Takumy. – M.: Mir. 1989. 310 p. [in Russ.]
Lynch S. G. et al. Bragg-grating-stabilized external cavity lasers for gas sensing using tunable diode laser spectroscopy. Novel In-Plane Semiconductor Lasers XIII. – International Society for Optics and Photonics. 2014; 9002: 900209.
Lynch S. G. et al. External cavity diode laser based upon an FBG in an integrated optical fiber platform. Optics express. 2016; 24(8): 8391–8398.
Juodawlkis P. W. et al. High-power ultralow-noise semiconductor external cavity lasers based on low-confinement optical waveguide gain media. Novel In-Plane Semiconductor Lasers IX. – International Society for Optics and Photonics. 2010; 7616: 76160X.
Belovolov M. I., Dianov E. M., Duraev V. P. et al. Poluprovodnikovye lazery s gibridnym rezonatorom na volokonnyh breggovskih reshetkah. – M.: IOFAN. 2002. 67 p.
Duraev V., Medvedev S. Single-Frequency Semiconductor Lasers Based on Two-Pass Amplifiers. Fotonika. 2015; 9(6):54–61. URL: [www.photonics.su/journal/article/4987].
ABOUT AUTHORS
Duraev V. P., Doctor of Technical Sciences, JSC “New Laser Technology”,
http://nolatech.ru, Moscow, Russia.
ORCID:0000-0002-2701-0335
Voronchenko S. A., JSC “New Laser Technology”, http://nolatech.ru, Moscow, Russia.
ORCID: 0000-0002-3913-1097
Molodtsov I.S., JSC “New Laser Technology”, http://nolatech.ru, Moscow, Russia.
Contribution by the members of the team of authors
The article was prepared on the basis of many years of work by all members of the team of authors.
Conflict of interest
The authors claim that they have no conflict of interest. All authors took part in writing the article and supplemented the manuscript in part of their work.
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