• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.17 no.1
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• pp.16-20
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• 2004

We present the fabrication and performance of wavelength tunable butt coupled (BT) sampled-grating (SG) distributed bragg reflector (DBR) - planar buried heterostructure (PBH) laser diodes (LD). The fabricated LD showed the high optical output power due to the high coupling efficiency between active and passive components by the BT coupling methods. The series resistance and diode ideality factor of LD were measured to be 3.7 $\Omega$ and 1.35, respectively. The average threshold current was 25 ㎃. The output powers of BT-SG DBR-PBH-LD were obtained to be as high as 12.3 and 24.56 ㎽ at 100 and 200 ㎃, respectively. The maximum wavelength tuning range was about 31 nm and the side mode suppression ratio was about 37 dB.

• Korean Journal of Optics and Photonics
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• v.28 no.5
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• pp.229-235
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• 2017

A widely tunable U-shaped SGDBR (Sampled Grating Distributed Bragg Reflector) laser diode is designed and analyzed by means of a time-domain simulation. The U-shaped SGDBR laser diode consists of SGDBR, active, phase, and TIR (Total Internal Reflection) mirror sections, so the coupling losses across the sections should be carefully considered. The tuning range of the designed U-shaped SGDBR laser is about 1525-1570 nm, which is confirmed by the simulation. The simulation results show that the loss in the TIR mirror region should be less than about 2 dB, and the refractive-index difference at the butt coupling between the passive and active regions should be less than 0.1, to provide the complete tuning range.

• ETRI Journal
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• v.45 no.1
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• pp.163-170
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• 2023

We report an electroabsorption modulator (EAM)-integrated distributed Bragg reflector laser diode (DBR-LD) capable of supporting a high data rate and a wide wavelength tuning. The DBR-LD contains two tuning elements, plasma and heater tunings, both of which are implemented in the DBR section, which have blue-shift and red-shift in the Bragg wavelength through a current injection, respectively. The light created from the DBR-LD is intensity-modulated through the EAM voltage, which is integrated monolithically with the DBRLD using a butt-joint coupling method. The fabricated chip shows a threshold current of approximately 8 mA, tuning range of greater than 30 nm, and static extinction ratio of higher than 20 dB while maintaining a side mode suppression ratio of greater than 40 dB under a window of 1550 nm. To evaluate its modulation properties, the chip was bonded onto a mount including a radiofrequency line and a load resistor showing clear eye openings at data rates of 25 Gb/s nonreturn-to-zero and 50 Gb/s pulse amplitude modulation 4-level, respectively.

• Korean Journal of Optics and Photonics
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• v.15 no.4
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• pp.369-374
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• 2004

In this paper, we propose a new tunable laser diode structure. The laser diode consists of a sampled-grating distributed feedback laser diode monolithically integrated with a sampled-grating distributed-Brags-Reflector. For a specific design, the possibility of continuous/discrete wavelength tuning over 27nm is confirmed by a numerical analysis using a split-step time domain model. Because the laser diode can be directly coupled with optical fiber without the intervention of the passive section, the laser diode exhibits higher output power than the conventional laser diode.

• Korean Journal of Optics and Photonics
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• v.15 no.5
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• pp.469-474
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• 2004

We have fabricated and designed wavelength-tunable sampled grating distributed Bragg reflector laser diodes(SGDBR-LD) by using, for the first time, planar buried heterostructures(PBH). The diodes have low threshold current values and high-performance of laser operation. Growth condition using metal organic chemical vapor deposition(MOCVD) was optimized for the formation of a good butt-coupling at the interface. A maximum output power of the fabricated device was 20 mW under 200 mA continuous wave(CW) operation at $25^{\circ}C$. Average threshold current and voltage were 12 mA and 0.8 V, approximately. This output power is higher than those of ridge waveguide(RWG) and buried ridge stripe(BRS) structures by amounts of 9 mW and 13 mW, respectively. We obtained a tuning range of 44.4nm which is well matched with the target value of our design. The side mode suppression ratio of more than 35 dB was obtained for the whole tuning range. Optical output power variation was less than 5 dB, which is 4 dB smaller than that of RWG structures.

• Current Optics and Photonics
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• v.4 no.6
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• pp.461-465
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• 2020

A dual-mode laser terahertz source consisting of two in-line distributed Bragg reflector (DBR) laser diodes (LD) is proposed. It is less susceptible to residual reflections from facets than an in-line dual-mode distributed feedback (DFB) LD. The characteristics of the proposed terahertz source are theoretically investigated using a split-step time-domain simulation. It is shown that terahertz waves of frequencies from 385 GHz to 1725 GHz can be generated by appropriate thermal tuning of two DBR LDs. The dual-mode DBR LD terahertz source exhibits good spectral quality for residual facet reflectivity below 0.02, but facet reflectivity of the in-line dual-mode DFB LD terahertz source should be below 0.002 to provide similar spectral quality.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.42 no.10 s.340
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• pp.19-28
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• 2005

In this paper, we analyzed tuning characteristics of the widely tunable SGDFB laser diode integrated with SGDBR. The improved time-domain model is used to analyse the laser diode. From the numerical analysis, the length of phase control region in the SGDFB section influences on the output power and the tuning range. Also, it was confirmed that the tuning range is affected by the length of the laser diode, the residual reflectivity at the facet, and the position of the facet.

• Korean Journal of Optics and Photonics
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• v.17 no.6
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• pp.544-547
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• 2006

A time-domain modeling approach is used to study characteristics of a widely tunable coupled-ring reflector (CRR) laser diode(LD). The CRR consists of a bus waveguide and two coupled ring resonators coupled to the bus without resorting to distributed Bragg grating structure. The tuning range can be a few tens of nanometers with a side mode suppression ratio exceeding 35dB through the adjustment of currents into the phase control sections in the rings. The CRR laser diode has long effective cavity length compared to conventional laser diodes. Accordingly, a broad additional resonance peak in the amplitude modulation characteristics is observed between 20 to 30 GHz, implying the extension of amplitude modulation bandwidth.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.40 no.9
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• pp.666-672
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• 2003

In this paper, we described the fabrication and the performance of wavelength tunable distributed bragg reflector (DBR) laser diode (LD), having different waveguide coupling mechanisms; integrated-twin-guide (ITG) DBR-LD and butt coupled (BT) DBR-LD. This deviceis fabricated by metal organic vapor phase epitaxy (MOVPE) growth and planar buried heterostructure (PBH)-type transverse current confinement structure. The result of measurement, the optical performance of BT-DBR-LD is better over 2 times than that of ITG-DBR-LD at the variation of threshold current and output power, and slop efficiency due to the higher coupling efficiency of the butt coupled structure than the integrated twin guide structure. The maximum wavelength tuning range is about 7.2nm for ITG DBR-LD and 7.4nm for BT DBR-LD. Both types of lasers have a very high yield of single mode operation with a side-mode suppression ratio of more than 35dB.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.36D no.2
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• pp.81-89
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• 1999

Among various wavelength conversion technologies, that using the cross-gain modulation in laser diode makes it possible to deal with the high speed signal quite simply and efficiently. In this paper, presented was the applicability of an improved time-domain large-signal dynamic model as a CAD tool to analyzed the characteristics of SSGDBR(Superstructure Grating Distributed Bragg Reflector) laser diodes used for wavelength converters. Using this model, it was shown that this kind of wavelength converter can provide the widely tunable wavelength conversion of the high speed data above 10 Gbps. We also investigated the effect of input optical power and the bias current on the characteristics of the device such as extinction ration and eye diagram. The modeling results show very similar trend to the experimental reports.