Optimized design of QD-LD toward QD-SOA to achieve 35-dB maximum chip gain with 400-mA injected current

Boriboon, Budsara; Worasucheep, Duang-rudee; Matsumoto, Atsushi; Akahane, Kouichi; Yamamoto, Naokatsu; Wada, Naoya

doi:10.1016/j.optcom.2020.126238

Cited by 6 publications

(5 citation statements)

References 30 publications

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“…For example, the Rapid Thermal Annealing (RTA) in [8] helps to obtain a high internal quantum efficiency of 66.39% and low optical loss of 9.87 cm -1 in QD-laser. Using the strain compensation technique, the 35-dB highest chip gain was achieved in QD-SOA with 25 stacked QD layers at 400-mA bias current [9] based on previous works [10][11]. In addition, QD-SOA can operate at very high bit rates up to 40 Gb/s and support several modulation formats, such as 8-PSK [5], 16-QAM [5,12], and PAM4 [6][7].…”

Section: Introductionmentioning

confidence: 85%

“…The data output of PD#2 in Fig. 12 has 5 noises [26]: shot, signal-ASE beat, ASE-ASE beat, thermal, and dark current, as in ( 5) - (9). All parameters and their values are declared in Table III.…”

Section: ) Noise Termsmentioning

confidence: 99%

“…Our QD-SOA is in-house developed having almost the same structure as in [9]. It has ridge structure with active InAs QDs separated by InGaAlAs spacing layers on InP(311)B substrate grown by Molecular Beam Epitaxy.…”

Section: Introductionmentioning

confidence: 99%

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Performances of Conventional SOAs Versus QD-SOA in 1530-nm Upstream Transmission of 40 Gb/s Access Network

et al. 2022

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SOA is the key device for burst-mode upstream transmission of 40 Gb/s access network to extend distance and increase users. We evaluate two conventional SOAs and our QD-SOA in networks, consisting of 20-km Single Mode Fiber (SMF) and splitters (1:8, 1:16 & 1:32). First, their characteristics are reported: 3-dB bandwidth & peak wavelength of Amplified Spontaneous Emission (ASE) spectra, gain, saturation output & input, and Noise Figure (NF). QD-SOA gives the lowest NF of 4.59 dB at -20-dBm input due to its highest Optical Signal to Noise Ratio (OSNR). It also has the fastest response time (70 ps) with less data pattern effect when operating in saturation region. Besides the measurement of Input Power Dynamic Range (IPDR) of 3 SOAs, their performances of single versus two-cascaded SOA transmissions are evaluated by Bit Error Rate (BER) in many combinations of SMF and splitters. In case of inserting 1:8 splitter between two-cascaded SOAs, the performance of 2 nd -stage QD-SOA has lower BERs than 2 nd -stage conventional SOA due to its higher saturation output and less pattern effect when operating at high input power. Finally, both experimental and computed BERs are plotted versus SOA's input to confirm the OSNR degradation and data pattern effect.

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Section: Introductionmentioning

confidence: 85%

Section: ) Noise Termsmentioning

confidence: 99%

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Performances of Conventional SOAs Versus QD-SOA in 1530-nm Upstream Transmission of 40 Gb/s Access Network

et al. 2022

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“…Therefore, this study also focused on QDs, employing the strain compensation technique, [ 25,26 ] which enables a highly stacked QD structure with more than 300 layers, [ 25 ] owing to the prevention of the degradation of the QD quality, and QD‐SOAs and QD‐LDs were successfully fabricated in the 1.55 μm band grown on an InP(311)B substrate. [ 27–31 ] Moreover, this study already demonstrated heterogeneous integrated devices, such as tunable LDs [ 32–34 ] and dual‐wavelength lasers, for the signal source in the access network that used radio over fiber technique, [ 35 ] with QD‐and Si photonics‐based PICs in the O‐band and 1 μm band (1.0−1.26 μm, which we call T‐band). [ 36 ] However, the threshold current of the fabricated QD‐LD was insufficient because the design of the device was not optimized.…”

Section: Introductionmentioning

confidence: 99%

Laser Characteristic and Strain Distribution Dependence on Embedding Layer Thickness of Quantum Dots Laser Diodes Grown on InP(311)B Substrate

Matsumoto

Akahane

Umezawa

et al. 2021

Physica Status Solidi (a)

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Herein, 14 layer‐stacked quantum dots laser diodes (QD‐LDs) are fabricated with different thicknesses of embedding layers grown on InP(311)B substrate, and the lowest threshold current (Ith) of 21.6 mA is demonstrated in an as‐cleaved ridge‐structured QD‐LD with 13 nm‐thick embedding layers. Ith has the minimum value when the thickness is 13 nm. The factors unique to QDs grown on an InP(311)B substrate are assumed as the overlap integral of the wavefunction of electrons and holes and the decrease in gain owing to the formation of a miniband. According to the simulation results of the local strain profile in the embedding and QD layers, the strain in the QD and embedding layer is higher in the case of 7 nm thickness than in the case of 20 nm thickness. As a result of the large strain, because the thickness of the embedding layer decreases, a large internal electric field tends to be generated, causing the wavefunctions to become largely separated and localized. Therefore, the overlap integral of the wavefunction becomes smaller, and because of the decrease in the radiation recombination probability, the internal quantum efficiency also decreases, causing the characteristic of Ith on the thickness of the embedding layer.

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“…[32] helps to obtain a high internal quantum efficiency of 66.39 % and low optical loss of 9.87 cm -1 in QD-laser. Using the strain compensation technique, the 35-dB highest chip gain was achieved in QD SOA with 25 stacked QD layers at 400-mA bias current [63] based on previous works [10,57]. In addition, QD SOA can operate at very high bit rates up to 40 Gb/s and support several modulation formats, such as 8-PSK [36], 16-QAM [36,43] and PAM4 [37,38].…”

Section: Introductionmentioning

confidence: 84%

Characteristics improvement of quantum dot semiconductor optical amplifier for access network

Boriboon¹

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This thesis presents the characteristics improvement and performance evaluation of Quantum Dot Semiconductor Optical Amplifier (QD SOA) in an access network. There are 3 parts: 1) improvement of internal quantum efficiency, 2) increase of chip gain and 3) implementation of QD SOA in 40 Gb/s access network. The first part, Rapid Thermal Annealing (RTA) is applied to improve internal quantum efficiency to be 1.4 times higher than without RTA and low optical loss. The second part, strain compensation technique is applied to increase the chip gain of QD SOA. Considering the design of Quantum Dot Laser Diode with optimized stacked QD layers and threshold current, then the same design is applied to QD SOA having 25-stacked QD layers and 2 mm long. It can achieve the maximum chip gain of 35 dB at 400-mA bias current. The last part of thesis, the performances of two conventional SOAs and one QD SOA are evaluated in 40 Gb/s access network. Starting from the characteristics between conventional SOAs and QD SOA are compared. QD SOA gives the lowest Noise Figure of 4.59 dB because of its highest Optical Signal to Noise Ratio (OSNR). Plus, QD SOA has the fastest response time of 70 ps with the lowest data pattern effect when operating in saturation region, which is suitable for burst-mode transmission. Next, the performance of single SOA transmission is evaluated, and the Input Power Dynamic Ranges (IPDR) of 3 SOAs are measured. Finally, the two-cascaded SOA is experimented to raise power budget of a network to successfully support 128 users and 20-km distance. Consequently, installing QD-SOA as 2nd-stage SOA following a conventional SOA provides lower Bit Error Rates (BERs) than two-cascaded conventional SOAs because QD SOA has higher saturation output power and lower data pattern effect when operating at high input power. Additionally, the BERs are computed by substituting all parameters from experiments into theoretical equations. They are compared to experimental BERs to confirm the root cause of OSNR degradation and data pattern effect.

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Optimized design of QD-LD toward QD-SOA to achieve 35-dB maximum chip gain with 400-mA injected current

Cited by 6 publications

References 30 publications

Performances of Conventional SOAs Versus QD-SOA in 1530-nm Upstream Transmission of 40 Gb/s Access Network

Performances of Conventional SOAs Versus QD-SOA in 1530-nm Upstream Transmission of 40 Gb/s Access Network

Laser Characteristic and Strain Distribution Dependence on Embedding Layer Thickness of Quantum Dots Laser Diodes Grown on InP(311)B Substrate

Characteristics improvement of quantum dot semiconductor optical amplifier for access network

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