Milestone-Proposal:Dynamic single-mode semiconductor laser

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Docket #:2023-25

This proposal has been submitted for review.


To the proposer’s knowledge, is this achievement subject to litigation? No

Is the achievement you are proposing more than 25 years old? Yes

Is the achievement you are proposing within IEEE’s designated fields as defined by IEEE Bylaw I-104.11, namely: Engineering, Computer Sciences and Information Technology, Physical Sciences, Biological and Medical Sciences, Mathematics, Technical Communications, Education, Management, and Law and Policy. Yes

Did the achievement provide a meaningful benefit for humanity? Yes

Was it of at least regional importance? Yes

Has an IEEE Organizational Unit agreed to pay for the milestone plaque(s)? Yes

Has an IEEE Organizational Unit agreed to arrange the dedication ceremony? Yes

Has the IEEE Section in which the milestone is located agreed to take responsibility for the plaque after it is dedicated? Yes

Has the owner of the site agreed to have it designated as an IEEE Milestone? Yes


Year or range of years in which the achievement occurred:

1978-

Title of the proposed milestone:

Single-Mode Semiconductor Laser for Long-Wavelength Optical Fiber Communication, 1978

Plaque citation summarizing the achievement and its significance:

At Tokyo Institute of Technology, the single-mode semiconductor laser for long-wavelength optical fiber communication was realized and pioneered, ensuring consistent single-mode operations even under high-speed direct modulations. By integrating wavelength-tunable function into a laser cavity, the single-mode laser propelled advancements in high-capacity optical fiber communications, fundamentally shaping our present internet society.

200-250 word abstract describing the significance of the technical achievement being proposed, the person(s) involved, historical context, humanitarian and social impact, as well as any possible controversies the advocate might need to review.

Honorary Professor Yasuharu Suematsu, Tokyo Institute of Technology, realized the single-mode semiconductor laser characterized by unwavering single-mode operations even under high-speed modulations, in the minimum-loss wavelength band suitable for ultra-high-capacity and long-haul optical fiber transmissions. Preferential laser materials in the minimum-loss-wavelength band for silica fibers, namely, the 1.5-µm region were also developed. Then, he realized the single-mode operation even under high-speed direct modulation in the wavelength band of 1.3 and 1.5 µm with basis of the long-wavelength laser material and the single-wavelength resonator. The invention was opened to industries and was intended for early commercialization of long-distance fiber communication systems. These achievements opened door for high-capacity optical fiber communications and contributed to the evolution of the Internet ICT society today. It is noted that some of the structures had been widely used for optical communication systems in later years. The pioneering work on long-wavelength single-mode lasers in optical fiber communications played a pivotal role in catapulting humanity into an era underscored by information and communication technology. In addition, an electrically-tunable single-mode semiconductor laser has been widely used as a light source for dense wavelength division multiplexing systems and for digital coherent communications. The achievement opened a door for broadband optical communications in global high-capacity networks, which constitute the backbone of the internet.

IEEE technical societies and technical councils within whose fields of interest the Milestone proposal resides.

IEEE Photonics Society

In what IEEE section(s) does it reside?

IEEE Tokyo Section

IEEE Organizational Unit(s) which have agreed to sponsor the Milestone:

IEEE Organizational Unit(s) paying for milestone plaque(s):

Unit: IEEE Tokyo Section
Senior Officer Name: Dr. Kiyoharu Aizawa

IEEE Organizational Unit(s) arranging the dedication ceremony:

Unit: IEEE Tokyo Section
Senior Officer Name: Dr. Kiyoharu Aizawa

IEEE section(s) monitoring the plaque(s):

IEEE Section: IEEE Tokyo Section
IEEE Section Chair name: Dr. Kiyoharu Aizawa

Milestone proposer(s):

Proposer name: Fumio Koyama
Proposer email: Proposer's email masked to public

Please note: your email address and contact information will be masked on the website for privacy reasons. Only IEEE History Center Staff will be able to view the email address.

Street address(es) and GPS coordinates in decimal form of the intended milestone plaque site(s):

Museum, Tokyo Institute of Technology, 2-12-1, O-okayama, Meguro-ku, Tokyo, 152-8550, Japan GPS: 35.606876, 139.684802

Describe briefly the intended site(s) of the milestone plaque(s). The intended site(s) must have a direct connection with the achievement (e.g. where developed, invented, tested, demonstrated, installed, or operated, etc.). A museum where a device or example of the technology is displayed, or the university where the inventor studied, are not, in themselves, sufficient connection for a milestone plaque.

Please give the address(es) of the plaque site(s) (GPS coordinates if you have them). Also please give the details of the mounting, i.e. on the outside of the building, in the ground floor entrance hall, on a plinth on the grounds, etc. If visitors to the plaque site will need to go through security, or make an appointment, please give the contact information visitors will need. Tokyo Institute of Technology Museum

Are the original buildings extant?

Yes, Professor Yasuharu Suematsu ’s laboratory existed in the Building S9 of the EE department of the Ookayama campus of Tokyo Institute of Technology between 1961-1994.

Details of the plaque mounting:

The milestone plaque will reside in the Tokyo Institute of Technology Museum, displayed alongside other significant commemorations marking Tokyo Institute of Technology's sesquicentennial legacy. The museum, situated proximate to the main campus entrance, welcomes the public on weekdays between 10:30 and 16:30.

How is the site protected/secured, and in what ways is it accessible to the public?

Visitors are subject to entrance security protocols.

Who is the present owner of the site(s)?

Tokyo Institute of Technology National University Corporation

What is the historical significance of the work (its technological, scientific, or social importance)? If personal names are included in citation, include justification here. (see section 6 of Milestone Guidelines)

Honorary Professor Yasuharu Suematsu, from Tokyo Institute of Technology, realized a long-wavelength single-mode semiconductor laser for high-capacity and long-haul optical fiber communications, as delineated in his review paper [A1, A2]. Single-mode operations under high-speed direct modulations and temperature variations were demonstrated [A3-A10]. This paradigm was actualized in a semiconductor laser operating in a long-wavelength band, now pivotal in long-haul fiber communications [A2].

The historical significance of the work is summarized as follows:

1. Prof. Yasuharu Suematsu realized and developed single-mode lasers at 1.3 µm and 1.5 µm wavelength band, coinciding with silica optical fibers' low transmission loss.

2. He accentuated the importance of single-mode operations, especially during high-speed direct modulations and/or current and temperature variations, for long-haul transmission via single-mode fiber.

3. He realized a wavelength tunable laser harnessed for dense wavelength division multiplexing systems of optical communications.

His endeavors in semiconductor laser research led to realizing high-capacity, long-haul optical fiber telecommunication, fostering the evolution of today’s internet society. His accomplishments are venerated as foundational in the realms of high-performance semiconductor lasers and broadband optical communication systems [A2].

(1) Demonstration of 1.3-µm and 1.5-µm wavelength single-mode semiconductor laser

Suematsu was extensively involved in the development of single-mode semiconductor lasers at the low-loss wavelength band of silica fibers in the 1.3-μm and 1.5-μm band with GaInAsP/InP long-wavelength materials. The first demonstration of single-mode lasers, emitting at 1.3 μm and 1.5 µm were realized in 1980 [A4-A9] as shown in Fig. 1. After the first long-wavelength laser, CW operation [A10] and single-mode operation at up to 3 GHz [A11], which was close to the relaxation frequency, were realized. The lasing wavelength was tuned smoothly without mode hopping in the FP lasers [A2]. Thus, thermally tunable single-mode operations were rendered operational.

Fig. 1. First demonstration of single-mode operation of 1.5-μm GaInAsP/InP LD [A9].

The report on the demonstration of the single-mode operation under rapid modulations in the 1.5-µm band in 1980 attracted much attention worldwide [A8]. Further, 1.5-μm-band single-mode semiconductor lasers were developed extensively as a light source for high-speed and long-distance optical fiber communications in the lowest-loss wavelength band at NTT and KDD in 1981. Utaka et al. developed 1.5-µm-band uniform DFB-LDs with one side facet mirror for commercial use as a thermally tunable single-mode lasers in 1981 [B1] and demonstrated single-mode operation at a modulation speed of 500 Mbits/s. T. Matsuoka et al. also reported on 1.51-µm-band uniform BH-DFB-LDs in 1982 [B2]. After these successful results, wideband optical fiber transmission experiments using 1.5–1.6-µm-band single-mode lasers spread worldwide [B3]–[B5], as summarized in [A2]. Subsequently, Sekartedjo et al. of Suematsu’s group realized 1.5-μm-band GaInAsP/InP phase-shifted DFB-LDs as shown in Fig. 2, which acted as high-yield single-mode-lasers in 1984 [A12]. Phase-shift regions at the center of the grating were realized by electron-beam direct writing [A13]. Uniform DFB-LDs with one side facet mirror had a lower production yield owing to indeterminate positioning in the facet-mirror relative to the grating periodicity. In contrast, phase-shifted DFB-LDs are used because of their high production yield. The latter are also used frequently in laser arrays because of their high yield in wavelength division multiplexing (WDM) systems. The phase-shifted 1.5-µm DFB-LDs, which evolved as the standard for thermally tunable single-mode lasers and 1.5-µm phase-shifted DFB-LD arrays, are used as wavelength-tunable (WT) lasers in which thermal tuning is applied by changing the laser mount temperature.

Fig. 2. Phase-shifted 1.5-μm GaInAsP/InP DFB laser as thermally-tunable LD in 1984 [A12].

The single-mode quality is evaluated by the side-mode suppression ratio (SMSR). The SMSR is defined as S0/S1, or the power of the lasing mode S0 relative to that of the suppressed side mode S1, to specify single-mode lasers. This was also given theoretically by Koyama and Komori of Suematsu’s group [A14], [A15] by using a spontaneous emission factor [A16]. The SMSR of a typical single-mode laser is around 40 dB. The term “SMSR” specifying single-mode operation was filed as a Japan Industrial Standard (JIS 0594041) in 1989 and internationally with the IEC (IEC60747-5-1;6.2.7.8) in 2002, representing the wide use of the concept of single-mode lasers [A2]. The development of single-mode lasers enabled the investigation of the detailed spectral behavior of semiconductor lasers. Koyama et al. of Suematsu’ group reported on spectral broadening, later called frequency chirping, under high-speed direct modulation in 1981 [A11]. This phenomenon causes a dynamic linewidth owing to the modulation of the carrier density in the active region. This dynamic wavelength shift becomes larger when the modulation speed is faster or the modulation depth is higher, as confirmed by a large signal modulation analysis in 1982 [A17]. Frequency chirping was formulated by a simple expression in terms of the linewidth enhancement factor defined by Koch and Bowers in 1984 [B6]. Also, Koyama and Suematsu reported on the relation between the spectral broadening under high-speed direct modulation and the related transmission bandwidth of optical fiber communication systems in 1985 [A18]. Distributed reflector (DR) laser which consists of distributed feedback (DFB) and distributed Bragg reflector (DBR) sections, which enabled an increase in the output power and efficiency, was proposed and demonstrated in 1988 by Suematsu’s research group [A19, A20] as shown in Fig. 3. DR lasers have been widely used as narrow-linewidth and tunable single-mode lasers for use in coherent optical communication systems today.

Fig. 3 First demonstration of distributed reflector (DR) laser which consists of distributed feedback (DFB) and distributed Bragg reflector (DBR) sections in 1988 [A19, A20].

(2) Electrically-tunable single-mode lasers

Electrically-tunable LDs with sections for tuning both the reflector wavelengths (Bragg wavelengths) and the phase shift by refractive index variations were proposed by Suematsu and Utaka in 1980 as electrically-tunable single-mode LDs. Their principle of tuning by injected carrier plasma at a 1.5-µm wavelength was demonstrated by Tohmori and Suematsu et al. by current injection into a phase control region in 1983 as shown in Fig. 4 [A21], and by current injection into the Bragg wavelength control region (DBR region) in 1986 [A22]. The wavelength stabilization within a temperature change between 6–46 ºC was also demonstrated [A23]. Wide wavelength tuning was demonstrated by NEC in 1987 by implementing both the phase and the Bragg-wavelength control regions [B7]. Resistive heating by a micro-heater was proposed for WT-LDs [B8]. WT-LDs with an extremely wide tuning ranges obtained using superstructure gratings (SSGs) and a sampled grating (SG) were developed by Tohmori and Yoshikuni et al. [B9] and Jayaraman et al. of Coldren’s group [B10], respectively, in 1993. WT-LDs using external reflector LDs, as an example [B11], were developed for narrow spectral operations. Electrically-tunable single-mode LDs are applicable for photonic integrated circuits (PICs) because other integrated optical elements also require specific thermal tuning.

Fig. 4. First demonstration of 1.5 µm wavelength tunable LDs with electronic phase tuning yielding continuous wavelength tuning of 0.4 nm in 1983 [A21].

(3) Societal Significance of Long-wavelength Single-mode Lasers

(a) Broad-band and Long-distance Optical Fiber Communications for infrastructure of ICT society

High-capacity and long-distance optical communications in the lowest-loss wavelength band of 1.5 µm use single-mode LDs as their light source and have progressed along with the research and development of optical fibers, optical devices, modulation schemes. Thermally-tunable single-mode lasers developed by this research have been commercially applied for long distances fiber communications—for overland trunk systems (1987) and for intercontinental submarine cables (1992)—and continue to support the progress of the Internet worldwide today. Additionally, since around 2004, electrically-tunable single-mode LDs (wavelength tunable lasers or WT-LDs) have been widely used as a light source to advance dense wavelength division multiplexing (DWDM) systems and for digital coherent communications. Today, optical fiber communications make up a highly dense communications network circling the globe tens of thousands of times, and are also used in intra- and inter- datacenter networks. Additionally, single-mode LDs are used for access networks in FTTH and mobile networks. Thus, the information transmission capability of optical fiber has reached several hundred thousand times as far as the coaxial cables preceding them, and significantly lowered the cost of transmitting information. Reflecting this, the mid-1990s saw network industries such as Amazon and Google appear one after the other. Optical fiber communications have progressed as the Internet has developed, and the instantaneous transmission of a large volume of knowledge is now a daily occurrence. In the electrical communication era of the 1960s, large volumes of data such as documents on which civilization depends, were circulated slowly in forms such as books. In contrast, the proliferation of high-capacity and long-distance optical fiber communications has allowed for large-volume information such as books to become used interactively in an instant. The pioneering work on long-wavelength single-mode lasers in optical fiber communications played a pivotal role in catapulting humanity into an era underscored by information and communication technology.

(b) Impacts of the long-wavelength single-mode laser

The advent of the single-mode laser auspiciously reshaped contemporary lasers utilized in long-haul fiber communication networks and digital coherent optical transmission systems. This innovation affected the yearly growth of the transmission capacity and distance product without an electronic repeater, directly modulated lasers for datacenter networks, narrow-spectral-width lasers, and so on.

What obstacles (technical, political, geographic) needed to be overcome?

(1) 1962–1970

When Suematsu started his research on semiconductor lasers for optical communications, semiconductor junction lasers based on GaAs [B12]–[B14] and GaAsP [B15] had been reported in 1962. However, they could operate in pulsed condition at room temperature because of high threshold current owing to the poor confinement of injected carriers and the optical mode field. In 1968, the upper limit of the modulation speed of LDs at the resonance-like frequency of direct modulation was found theoretically [A24] and confirmed experimentally by using pulsed LDs. Reduction of the threshold current was achieved by adopting a heterojunction structure, and a room-temperature continuous-wave (RT-CW) operation was demonstrated in 1970 [B16], [B17] by adopting a double-heterostructure (DH) [B18] that overcame the issue of poor confinement of injected carriers and the optical mode field.

(2) 1971–1980

The dynamics of semiconductor lasers had not matured. Hence, the modulation characteristics and mode control for both transverse modes and longitudinal modes were not well understood. Suematsu and his colleagues clarified the lasing mode selection mechanism in semiconductor lasers [A25]–[A27]. After reports on the realization of low-loss silica fibers in 1970s [B19], the minimum-transmission-loss wavelength of silica optical fibers was anticipated from around 1.3 µm to 1.7 µm [B19-B21]. Since the emission wavelength of semiconductor DH lasers consisting of AlGaAs/GaAs compound materials is 0.8–0.9 µm, new materials for the emission wavelength of 1.5–1.6 µm were eagerly anticipated. As a possible candidate, GaInAsP quaternary material grown on InP substrate was investigated [B22]. The RT-CW operation of a 1.1- µm wavelength was demonstrated in 1976 [B23]. However, there was a problem with so-called meltback in the liquid-phase-epitaxial (LPE) growth of the DH structure at emission wavelengths longer than 1.5 µm (i.e., GaInAsP material for the active layer dissolved into P-rich Indium solution during the growth of an InP cladding layer). This problem was solved by inserting an “anti-meltback layer” or by reducing the growth temperature of the InP cladding layer [A28], [A29], [B24]. In 1979, RT-CW operations of GaInAsP/InP lasers emitting at a wavelength longer than 1.5 µm were reported [A30], [A31], [B24]–[B26]. Moreover, semiconductor lasers with stable single-wavelength operation were required for wide-band optical fiber communications utilizing WDM systems. Semiconductor lasers for wavelength discrimination, such as distributed feedback (DFB), distributed-Bragg-reflector (DBR), and coupled cavity structures, was widely investigated. The single-wavelength operation of GaInAsP/InP lasers under high-speed direct modulation was achieved at a wavelength of 1.3 µm and 1.5 µm in 1980 [A6, A7].

The transverse mode control of 1.5-µm single-mode LDs was performed using a buried hetero (BH) structure that was originally developed for AlGaAs/GaAs systems [B27] without success owing to oxidation problems with the Al component. The BH structure was effectively applied to InGaAsP/InP systems where the oxidation problems with the Al component were eliminated.

(3) 1981–1988

The minimum transmission loss wavelength of low-loss silica fiber was found to be in the 1.5–1.6 µm range. The chromatic dispersion of such fibers strictly limits the transmission distance and data rates, thus the stable single-wavelength operation of semiconductor lasers even under high-speed modulation was highly required. In addition, semiconductor laser dynamics (especially wavelength chirping under rapid direct modulation) were investigated for middle-distance communications both experimentally [A11] and theoretically in the early 1980s [A17], [A18].

After stable single-wavelength operations of semiconductor lasers were conducted under high-speed direct modulation, such lasers were named “dynamic-single mode (DSM)” or “single-longitudinal mode (SLM)” lasers for short. They were demonstrated as thermally-tunable or electrically-tunable single-mode LDs, and were applied to WDM systems and then in digital coherent systems. In the early 1980s, the limited yield of production of uniform DFB-LDs with one facet mirror became a practical problem. This was solved by using phase-shifted DFB-LDs, where the lithographic formation of a nonuniform grating pitch was implemented with an electron-beam exposure device by a variable anode voltage supply [A13].

Distributed reflector (DR) laser enabled an increase in the output power and reducing a laser linewidth, was demonstrated in 1988 by Suematsu’s research team [A19, A20]. DR lasers have been widely used for narrow-linewidth and tunable single-mode lasers for use in coherent optical communication systems today [B28].

What features set this work apart from similar achievements?

(1) The features of this work

As the highlight of this work, during the nascent epoch of optical fiber telecommunication research, Suematsu pioneered the design of a semiconductor laser characterized by unwavering single-mode operations, even under high-speed modulations, in the minimal-loss wavelength band suitable for ultra-high-capacity and long-haul optical fiber transmissions. Subsequently, he christened these lasers as single-mode lasers. To realize this laser, he insisted on long-distance fiber transmission. Thus, he developed preferential laser materials in the lowest-loss-wavelength band for silica fibers, namely, the 1.5-µm region. Then, he realized single-mode LDs in the wavelength band of 1.3 µm and 1.5–1.6 µm with basis of the laser material and the single-wavelength resonators. The material process was opened to industries and was intended for early commercialization of long-distance fiber communication systems. These achievements opened door for high-capacity optical fiber communications and contributed to the evolution of the Internet ICT society. There had been a considerably numerous works related to integrated optics after S. E. Miler presented a concept of “integrated optics”. It is noted that some of the structures had been introduced in the semiconductor lasers in later years.

(2) Related achievements

(a) Longitudinal mode control: Kogelnik and Shank of Bell Labs theoretically predicted refractive-index-coupled DFB lasers by the use of grating structures on waveguides in 1972 [B4]. Before presenting their theory, they demonstrated a DFB dye laser in 1971 [B30]. In the same year, Kaminow and Weber demonstrated distributed Bragg reflector (DBR) dye lasers [B31]. However, a two-mode operation problem existed. The use of an asymmetric taper for the purpose of phase shifting was proposed by Haus and Shank in 1976 [B32] and by Tada et al. in 1977 [B33]. Wang of UC Berkeley reported on a theory of DFB and DBR lasers that was similar to Kogelnik’s theory in 1974 [B34]. Suematsu and Hayashi theoretically proposed that single-longitudinal-mode operation is available in lasers consisting of two refractive-index-coupled distributed reflectors connected to each other with a suitable phase shift in length in 1974 [A32]. GaAlAs/GaAs DFB lasers using optical pumping were demonstrated by Nakamura et al. of Caltech in 1973 [B35]. In 1975, Streifer et al. of Xerox pointed out theoretically that single-mode operation in uniform DFB lasers could be attained by using additional axially asymmetric side facet mirrors with a proper phase shift [B36].

(b) Long-wavelength semiconductor lasers: Investigations of GaInAsP long-wavelength lasers on InP substrate were led by Hshie of MIT, and an RT-CW operation with a 1.1- µm wavelength was demonstrated in 1976 [B25]. The realization of the RT-CW operation of 1.5–1.6 µm wavelength lasers was reported at almost the same time, in August 1979 [A16] and in September 1979 by Akiba of KDD [B26], Kawaguchi of NTT [B27], and Kaminow of Bell Labs [B28].

(c) Wavelength-tunable semiconductor lasers: As for wavelength-tunable semiconductor lasers, Okuda et al. proposed and calculated the wavelength tunability of distributed Bragg-reflector lasers by loss modulation in 1976 [B37] and by the carrier plasma effect in 1977 [B38]. There seems no successive follows on these works. For practical DSM-laser, 1.5-μm-band uniform DFB-LDs with one side facet mirror were developed in 1981–1982 [B6], [B7] as DSM-LDs with thermal wavelength tuning by varying the laser mount temperature. Tunable lasers with an extremely wide tuning range obtained using SSGs and an SG were developed by Tohmori and Yoshikuni et al. [B14] and Jayaraman et al. of Coldren’s group [B15], respectively in 1993. Coldren pointed out that the wide wavelength tunability was owing to the Vernier effect. Tunable lasers using thermal refractive index variations in both the resonators and phase sections [B12], and external reflector lasers as an example [B16] were developed for narrow spectral operations in 1991.

Supporting texts and citations to establish the dates, location, and importance of the achievement: Minimum of five (5), but as many as needed to support the milestone, such as patents, contemporary newspaper articles, journal articles, or chapters in scholarly books. 'Scholarly' is defined as peer-reviewed, with references, and published. You must supply the texts or excerpts themselves, not just the references. At least one of the references must be from a scholarly book or journal article. All supporting materials must be in English, or accompanied by an English translation.

A: References related directly to the work by Yasuharu Suematsu and his group:

[A1] Y. Suematsu, “Long-wavelength optical fiber communication,” Proc. IEEE, Vol. 71, No. 6, pp. 692–721, June 1983.

[A2] Y. Suematsu, “Dynamic single-mode lasers,” J. Lightwave Technology, Vol. 32, No. 6, pp. 1144-1158, March 15, 2014.

[A3] Y. Suematsu and K. Iga, “Integrated GaInAsP/InP laser,”1st Europ. Conf. Integrated Optics, pp. 70–75, Sep. 1981.

[A4] H. Kawanishi, Y. Suematsu, Y. Itaya and S. Arai, “GaInAsP/InP Injection Laser Partially Loaded with Distributed Bragg Reflector”, Jpn. J. Appl. Phys., Vol. 17, No. 8, pp. 1439-1440, April 1978

[A5] H. Kawanishi, Y. Suematsu, K. Utaka, Y. Itaya and S. Arai, “GaInAsP/InP Injection Laser Partially Loaded with First-Order Distributed Bragg Reflector”, IEEE Journal of Quantum Electrics, vol. QE-15, no. 8, pp.701-706, August 1979

[A6] Y. Sakakibara, K. Furuya, K. Utaka, and Y. Suematsu, “Single-mode oscillation under high-speed direct modulation in GaInAsP/InP integrated twin-guide lasers with distributed Bragg reflectors,” Electron. Lett., vol. 6, no. 12, pp. 456–458, June 1980.

[A7] K. Utaka, K. Kobayashi, K. Kishino and Y. Suematsu, “1.5–1.6 μm GaInAsP/InP Integrated twin-guide lasers with first-order distributed Bragg reflectors,” Electron. Lett., vol. 16, no. 12, pp. 455–456, June 1980.

[A8] K. Utaka, K. Kobayashi, F. Koyama, Y. Abe, and Y. Suematsu, “Single wavelength operation of 1.53μm GaInAsP/InP BH integrated twin guide lasers with distributed Bragg reflector under direct modulation up to 1GHz,” Electron. Lett., vol. 17, no. 11, pp. 368–369, May 1981.

[A9] K. Utaka, K. Kobayashi, and Y. Suematsu, “Lasing characteristics of GaInAsP/InP integrated twin-guide lasers with first-order distributed Bragg reflectors,” IEEE J. Quantum Electron., vol. QE-17, no. 5, pp. 651–658, May 1981.

[A10] K. Kobayashi, K. Utaka, Y. Abe, and Y. Suematsu, "CW Operation of 1.5-1.6μm Wavelength GaInAsP/InP BH Integrated Twin Guide Lasers with Distributed Bragg Reflector," Electron. Lett., Vol.17, No.11, pp.366-368, May 1981.

[A11] F. Koyama, S. Arai, Y. Suematsu, and K. Kishino, “Dynamic spectral width of rapidly modulated 1.58 µm GaInAsP/InP buried- heterostructure distributed-Bragg-reflector integrated-twin-guide lasers,” Electron. Lett., vol. 17, no. 25/26, pp. 938–940, Dec. 1981.

[A12] K. Sekartedjo, N. Eda, K. Furuya, Y. Suematsu, F. Koyama, and T. Tanbun-Ek, “1.5 μm phase-shifted DFB lasers for single-mode operation,” Electron. Lett., Vol. 20, No. 2, pp. 80–81, Jan. 1984.

[A13] K. Furuya, K. Yoshida, K. Honjo, and Y. Suematsu, "Precise Control of Grating Pitch by Electron-Beam Exposure System for Integrated Optics," Trans. IECE of Japan. Vol.E66, No.9, pp.561-562, Sept. 1983.

[A14] F. Koyama, Y. Suematsu, S. Arai, T. Tanbun-Ek, “1.5-1.6 µm GaInAsP/InP dynamic-single-mode (DSM) lasers with distributed Bragg reflector,” IEEE Journal of Quantum Electronics 19 (6), 1042-1051, June 1983.

[A15] K. Komori, S. Arai, Y. Suematsu, I. Arima, and M. Aoki, "Single-Mode Properties of Distributed-Reflector Lasers," IEEE J. Quantum Electron., Vol.25, No.6, pp.1235-1244 (June 1989).

[A16] Y. Suematsu and K. Furuya, “Theoretical Spontaneous Emission Factor of Injection Lasers,” Trans. IECE of Jpn., Vol. E60, No. 9, pp. 467–472, Sept. 1977.

[A17] K. Kishino, S. Aoki, and Y. Suematsu, “Wavelength variation of 1.6 μm wavelength buried heterostructure G2aInAsP/InP lasers due to direct modulation,” IEEE J. Quantum Electron., Vol. QE-18, No. 3, pp. 343–351, Mar. 1982.

[A18] F. Koyama and Y. Suematsu, “Analysis of dynamic spectral width of dynamic-single-mode (DSM) lasers and related transmission bandwidth of single-mode fibers,” IEEE J. Quantum Electron., Vol. QE-21, No. 4, pp. 292–297, Apr. 1985.

[A19]. K. Komori, S. Arai, Y. Suematsu, M. Aoki, and I. Arima, "Proposal of Distributed Reflector (DR) Structure for High Efficiency Dynamic Single Mode (DSM) Lasers," Trans. IEICE of Japan, Vol.E71, No.4, pp.318-320, Apr. 1988.

[A20]. S. Pellegrino, K. Komori, H. Suzuki, K. S. Lee, S. Arai, Y. Suematsu, and M. Aoki, "Novel Single-Longitudinal-Mode 1.5μm GaInAsP/InP Distributed Reflector (DR) Laser," Electron. Lett., Vol.24, No.7, pp.435-437, Mar. 1988.

[A21] Y. Tohmori, Y. Suematsu, Y. Tsushima, and S. Arai, “Wavelength tuning of GaInAsP/InP integrated laser with butt-jointed built in distributed Bragg reflector,” Electron. Lett., Vol. 19, No. 17, pp. 656–657, Aug. 1983.

[A22] Y. Tohmori, K. Komori, S. Arai, Y. Suematsu, and H. Oohashi: “Wavelength tunable 1.5 μm GaInAsP/InP bundle-integrated-guide distributed-Bragg-reflector (BIG-DBR) lasers,” Trans. IECE, Japan, Vol. E68, No. 12, pp. 788-790, Dec. 1985.

[A23] Y. Tohmori, H. Oohashi, T. Kato, S. Arai, K. Komori, and Y. Suematsu: “Wavelength stabilization of 1.5 μm GaInAsP/InP bundle-integrated-guide distributed-Bragg-reflector (BIG-DBR) lasers integrated with wavelength tuning region,” Electron. Lett., Vol. 22, No. 3, pp. 138-140, Feb. 1986.

[A24] T. Ikegami and Y. Suematsu, “Resonance-like characteristics of the direct modulation of a junction laser,” Proc. IEEE, Vol. 55, No. 1, pp. 122–123, Jan. 1967.

[A25] Y. Suematsu, M. Yamada, and K. Hayashi, " A Multi-Hetero-AlGaAs Laser with Integrated Twin-Guide," Proc. IEEE, Vol.63, No. 1, pp.208-209, Jan. 1975.

[A26] M. Yamada, H. Nishizawa, and Y. Suematsu, “Mode selectivity in integrated twin-guide lasers,” Trans. IECE Japan., Vol. E59, No. 7, pp. 9–10, July 1976.

[A27] Y. Suematsu, K. Kishino, and T. Kambayashi, “Axial mode selectivities for various types of integrated twin-guide lasers,” IEEE J. Quantum Electron., Vol. QE-13, No. 8, pp. 619–622, Aug. 1977.

[A28] S. Arai, Y. Itaya, Y. Suematsu, K. Kishino, and S. Katayama, "Condition of LPE Growth for Lattice matched GaInAsP/InP DH Lasers with (100) Substrate in the Range of 1.2-1.5μm," Japan. J. Appl. Phys., Vol.17, No.11, pp.2067-2068, Nov. 1978.

[A29] S. Arai, Y. Suematsu, and Y. Itaya,, “1.67 µm Ga0.47In0.53As/InP DH Lasers Double Cladded with InP by LPE Technique,” Jpn. J. Appl. Phys., Vol. 18, No. 3, pp. 709–710, Mar. 1979.

[A30] S. Arai, Y. Itaya, Y. Suematsu, and K. Kishino, “1.5–1.6 μm wavelength (100) GaInAsP/InP DH lasers,” in Proc. 11th Conf. Solid State Devices, Tokyo, Japan, Aug. 1979, pp. B-3–B-4.

[A31] S. Arai, M. Asada, Y. Suematsu, and Y. Itaya, “Room temperature CW operation of GalnAsP/InP DH laser emitting at 1.51 μm,” Jpn. J. Appl. Phys., Vol. 18, No. 12, pp. 2333–2334, Dec. 1979.

[A32] Y. Suematsu and K. Hayashi, “General analysis of distributed Bragg reflector and laser resonator using it,” in Nat. Convention of IECE, 1200, p. 1203, July 1974 (Original in Japanese).

B: References related to work done by groups other than Yasuharu Suematsu:

[B1] K. Utaka, S. Akiba, K. Sakai, and Y. Matsushima, “Room-temperature CW operation of distributed feedback buried- heerostructure InGaAsP/InP lasers emitting at 1.57 µm,” Electron. Lett., vol. 17, no. 25/26, pp. 961–963, Dec. 1981.

[B2] T. Matsuoka, H. Nagai, Y. Itaya, Y. Noguchi, Y. Suzuki, and T. Ikegami, “CW operation of DFB-BH GaInAsP/InP lasers in 1.5 μm wavelength region,” Electron. Lett., vol. 18, no. 1, pp. 27–28, Jan. 1982.

[B3] T. Yamamoto, K. Utaka, S. Akiba, K. Sakai, Y. Matsushima, S. Sakaguchi, and N. Seki, “280 Mbit/s single-mode fiber transmission with DFB laser diode emitting at 1.53 µm,” Electron. Lett., vol. 18, no. 5, pp. 239–240, Mar. 1982.

[B4] T. Ikegami, K. Kuroiwa, Y. Itaya, S. Shinohara, K. Hagimoto, and N. Ikegami, “1.5 µm transmission experiment with distributed feedback,” 8th Europ. Conf. Opt. Commun. (ECOC’82), Cannes, Sept. 1982.

[B5] R. A. Linke, B. L. Kasper, J. C. Campbell, A. G. Dentai, and I. P. Kaminow, “120 km lightwave transmission experiment at 1 Gbit/s using a new long-wavelength avalanche photodetector,” Electron. Lett., vol. 20, no. 2, pp. 498–499, June 1984.

[B6] T. L. Koch and J. E. Bowers, “Nature of wavelength chirping in directly modulated semiconductor lasers,” Electron. Lett., Vol. 20, No. 25/26, pp. 1038–1040, Dec. 1984.

[B7] S. Murata, I. Mito, and K. Kobayashi, “Over 720GHz (5.8nm) frequency tuning by a 1.5 μm DBR laser with phase and Bragg wavelength control regions,” Electron. Lett., Vol. 23, No. 8, pp. 403–405, Apr. 1987.

[B8] S. L. Woodward, U. Koren, B. I. Miller, M. G. Young, M. A. Newkirk, and C. A. Burrus, “A DBR laser tunable by resistive heating,” IEEE Photon. Technol. Lett., Vol. 4, pp. 1330–1332, Dec. 1992.

[B9] Y. Tohmori, Y. Yoshikuni, H. Ishii, F. Kano, T. Tamamura, Y. Kondo, and M. Yamamoto, “Broad-range wavelength-tunable superstructure grating (SSG) DBR lasers,” IEEE J. Quant. Electron., Vol. 29, No. 6, pp. 1817-1823, June 1993.

[B10] V. Jayaraman, Z.-M. Chuang, and L. A. Coldren, “Theory, design, and performance of extended tuning range semiconductor lasers with sampled gratings,” IEEE J. Quantum Electron., Vol. 29, No. 6, pp. 1824-1834, June 1993.

[B11] H. Tsuda, K. Hirabayashi, Y. Tohmori, and T. Kurokawa, “Tunable light source using a liquid-crystal Fabry–Pérot interferometer,” IEEE Photon. Technol. Lett., Vol. 3, No. 6, pp. 504-506, Jun. 1991.

[B12] R. N. Hall, G. E. Fenner, J. D. Kingsley, T. J. Soltys, and R. O. Carlson, “Coherent light emission from GaAs junctions,” Phys. Rev. Lett., vol. 9, no. 9, pp. 366–368, Nov. 1962.

[B13] T. M. Quist, R. H. Rediker, R. J. Keyes, W. E. Krag, B. Lax, A. L. McWhorter, and J. Zeiger, “Semiconductor maser of GaAs,” Appl. Phys. Lett., Vol. 1, No. 4, pp. 91–92, Dec. 1962.

[B14] M. I. Nathan, W. P. Dumke, G. Burns, F. H. Dill, Jr., and G. Lasher, “Stimulated emission of radiation from GaAs p-n junctions,” Appl. Phys. Lett., Vol. 1, No. 3, pp. 62–64, Nov. 1962.

[B15] N. Holonyak, Jr. and S. F. Bevacqua, “Coherent (visible) light emission fromGa (As1−x Px ) junctions,” Appl. Phys. Lett., Vol. 1, No. 4, pp. 82–83, Dec. 1962.

[B16] Zh. I. Alferov, V. M. Andreev, E. L Portnoi, and M. K. Trukan, “AlAs-GaAs heterojunction injection lasers with a low room-temperature threshold,” Fiz. Tekh. Poluprov., vol. 3, pp. 1328–1332, Sept. 1969. (Sov. Phys. Semicond., vol. 3, pp. 1107–1110, Mar. 1970.

[B17] I. Hayashi, M. B. Panish, P. W. Foy, and S. Sumski, “Junction lasers which operate continuously at room temperature,” Appl. Phys. Lett., Vol. 17, No. 3, pp. 109–111, Aug. 1970.

[B18] H. Kroemer, “A proposed class of heterojunction injection lasers,” Proc. IEEE, vol. 51, pp. 1782–1783, Dec. 1963.

[B19] D. B. Keck, R. D. Maurer, and P. C. Schultz, “On the ultimate lower limit of attenuation in glass optical waveguides,” Appl. Phys. Lett., vol. 22, no. 7, pp. 307–309, Apr. 1973.

[B20] M. Horiguchi and H. Osanai, “Spectral losses of low-OH-content optical fibres,” Electron. Lett., Vol. 12, No. 12, pp. 310–312, June 1976.

[B21] T. Miya, Y. Terunuma, T. Hosaka, and T. Miyashita, “An ultimately low-loss single-mode fiber at 1.55 μm,” Electron. Lett., Vol. 15, No. 4, pp. 106–108, Feb. 1979.

[B22] R. L. Moon, G. A. Antypas, and L. W. James, “Bandgap and lattice constant of GalnAsP as a function of alloy composition,” J. Electron. Mater., Vol. 3, No. 3, pp. 635-644, 1974.

[B23] J. Hsieh, J. A. Rossi, and J. P. Donnelly, “Room-temperature cw operation of GalnAsP/InP double-heterostructure diode lasers emitting at 1.1 μm,” Appl. Phys. Lett., Vol. 28, No. 12, pp. 709–711, June 1976.

[B24] S. Akiba, K. Sakai, Y. Matsushima, and T. Yamamoto, “Room-temperature C. W. operation of InGaAsP/InP heterostructure lasers emitting at 1.56 µm,” Electron. Lett., Vol. 15, No. 9, pp. 606-607, Sept. 1979.

[B25] H. Kawaguchi, T. Takahei, Y. Toyoshima, H. Nagai, and G. Iwane, “Room-temperature C.W. operation of lnP/InGaAsP/InP double heterostructure diode lasers emitting at 1.55 µm,” Electron. Lett., Vol. 15, No. 21, pp. 669-700, Oct. 1979.

[B26] I. P. Kaminow, R. E. Nahory, M. A. Pollack, L. W. Stulz, and J. C. DeWinter, “Single-mode C. W. ridge-waveguide laser emitting at 1.55 µm,” Electron. Lett., Vol. 15, No. 23, pp. 763-765, Nov. 1979.

[B27] T. Tsukada, “GaAs-Ga1−xAlxAs buried heterostructure injection lasers,” J. Appl. Phys., vol. 45, no. 11, pp. 4899–4906, Nov. 1974.

[B28] G. Kobayashi, K. Kiyota, T. Kimoto, T. Mukaihara, “Narrow linewidth tunable light source integrated with distributed reflector laser array”, 37th Optical Fiber Communications Conference, Tu2H.2., Sep. 2014.

[B29] H. Kogelnik and C. V. Shank, “Coupled wave theory of distributed feedback lasers,” J. Appl. Phys., Vol. 43, No. 5, pp. 2327–2335, May 1972.

[B30] H. Kogelnik and C. V. Shank, “Stimulated emission in a periodic structure,” Appl. Phys. Lett., Vol. 18, No. 4, pp. 152-154, Feb. 1971.

[B31] I. P. Kaminow and H. P. Weber, “Poly (methyl methacrylate) dye laser with internal diffraction grating resonator,” Appl. Phys. Lett., Vol. 18, No. 11, pp. 497-499, June 1971.

[B32] H. Haus and C. V. Shank, “Antisymmetric taper of distributed feedback lasers,” IEEE J. Quantum Electron., Vol. QE-12, No. 9, pp. 532-539, Sept. 1976.

[B33] K. Tada, Y. Nakano, and A. Ushirokawa, “Proposal of a distributed feedback laser with nonuniform stripe width for complete single-mode oscillation,” Electron. Lett., Vol. 20, No. 2, pp. 82-84, Jan. 1984.

[B34] S. Wang, “Principles of distributed feedback and distributed Bragg reflector lasers,” IEEE J. Quantum Electron., Vol. QE-10, No. 4, pp. 413-427, Apr. 1974.

[B35] M. Nakamura, A. Yariv, H. W. Yuen, S. Somekh, and H. L. Garvin, “Optically pumped GaAs surface laser with corrugation feed-back,” Appl. Phys. Lett., Vol. 22, No. 10, pp. 515-516, May 1973.

[B36] W. Streifer, B. D. Burnham, and D. R. Scifres, “Effect of external reflectors on longitudinal mode of distributed feedback lasers,” IEEE J. Quantum Electron., Vol. QE-11, No. 4, pp. 154-161, Apr. 1975.

[B37] M. Okuda, K. Murata, and K. Onaka, “Tunable distributed Bragg-reflector laser by modulating optical loss in corrugated waveguide,” Japan. J. Appl. Phys., Vol. 15, No. 5, pp. 911-912, May 1976.

[B38] M. Okuda and K. Onaka, “Tunability distributed Bragg-reflector laser by modulating refractive index in corrugated waveguide,” Japan. J. Appl. Phys., Vol. 16, No. 8, pp. 1501-1502, Aug. 1977.

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