Equivalent Circuit-Level Characterization of 1.55 µm Ingan Laser

Table of contents

1. Introduction

erhapse, the invention of lasers has been proven to be one of the most significant breakthroughs for technology in the last century [1]. Their applications extend to high speed communications, optical storage (e.g. CDs, DVDs, optical memories), barcode scanners in industrial machines, printers and even in medical science for spectroscopy and imaging, and also in destroying cancer tissues and unnecessary cells in human bodies [1][2]. In addition, modern technology facilitates with distance learning, online education and high speed online entertainment as well as instant communication from each corner of the world. This requires enormously data to be transported within a short period of time. Optical fiber communication system is one of the strongest candidates to overcome the associated problems.

The issues with the constraints of noise, bulk volume of data, amount of signal power transmission, interference with other networks and nearby RF electromagnetic fields are greatly settle down with optical fiber system [3][4]. Ideally, 1.55 ?m lasers are well suited for long haul communication at higher data rates due to minimal loss [5].

A growing interest on the group III-IV nitride based semiconductor materials has recently been prompted towards light emitting diodes, lasers and solar cells [9][10][11]. The wider (0.7 -6.2 eV) and direct bandgap, low electron effective mass, and high theoretical mobilities of these materials made them suitable for device applications [12]. A small amount of Ga in InN results in InGaN composite with 0.8 eV bandgap energy which is compatible with 1.55 ?m wavelength.

The equivalent circuit modeling (ECM) is required to clearly understanding the lasers' working conditions and to verify compatibility with associated electrical driver circuits. The ECM using Shockley equation transfers the carrier and photonics numbers into current and voltage quantities, respectively. Numbers of studies investigated the ECM for quantum dot and quantum cascaded lasers [13][14][15]. However, to the best of authors' knowledge, the ECM of the proposed In GaN based laser is still unreported, and thus requires attention.

2. P

In this paper, we investigate the electrical equivalent circuit characteristics of a previously proposed [16] InGaN based heterostructure laser diode. The static current-voltage (I-V), output power-input current (L-I), output voltage, and transient conditions are discussed briefly. PSPICE circuit simulator has been used to demonstrate the lasers' electrical characteristics.

A number of semiconductor alloys such as ternary, quaternary and quintuplet elements are used to fabricate 1.55 ?m laser diodes. For instance, materials including AlGaInAs, GaInNAsSb/GaAs, InGaAs/ InGaAs P, and GaInN AsSb/GaNAs [6][7][8] are the choices for the active layer of the lasers. However, often these ternary, quaternary and quintuplet materials are difficult to grow, and results in lasing problem. II.

3. PROPOSED LASER STRUCTURE

The schematic structure of the proposed 1.55 ?m quantum-well hetero structure lasers using InGaN is shown in Fig. 1. A c-plane sapphire wafer is used as the substrate. The LD structure consists of 0.6 µm thick n-In 0.15 Ga 0.85 N contact layer, 0.1 µm thick GaN cladding layer, 0.2 µm thick In 0.15 Ga 0.85 N guiding layer, and a 0.1 µm thick InGaN active layer.

4. III.

5. MATHEMATICAL MODEL

The rate equations for quantum well lasers are given by [17][18] ( ) 3 , where A, B, and C are the unimolecular, radiative, and Auger recombination coefficients, respectively; S = photon density = S tot /V a , where, S tot is again the total number of photons in the active volume; ? = ? A AN+? B BN 2 +? C CN 3 , where ? A , ? B , and ? C are coupling coefficients; P f = the output power, V a = is the volume of a single QW; ? i = is the currentinjection efficiency; Î?" c = is the optical confinement factor of one QW; g 0 = is the carrier dependent gain coefficient; ? p = is the photon lifetime; ?= is the lasing wavelength; ? c = is the output-power coupling coefficient; and ( )

( ) ( ) ( ) ( ) ( ) i 0 a n d N t I t N t N t S t ? g dt eV ? 1 ?S t = ? ? +(1)1 1 ?S t = +

the gain saturation term. ? dI I eV dt = and the stimulated emission component I 2 . The p-n heterojunction voltage V j can be represented by one ohmic resistance R e , series-connected with Shockley p-n junction diode (shown in Fig. 2).

6. IV.

7. MODEL IMPLEMENTATION

1 2 j d 0 d V C C 1 V ? ? ? = ? ? ? ? ?

, a junction depletion capacitance is added to the circuit, where C 0 is the zero bias depletion capacitance, V j is the junction voltage, V d is the build-in potential. Now, multiplying Eqn. ( 2) by eV a we get,

( ) ( ) ( ) ( ) ( ) ( ) 0 a a a c a c p n d S t S t ?N t g N t S t eV eV eV Î?" eV Î?" dt ? ? 1 ?S t = ? + + +(6)

which later reduces to

( ) ( ) ( ) ( ) ( ) p 0 c n c p d S t S t N t S t C G Î?" ?I Î?" dt R 1 ?S t + = + + (7)

Rearranging Eqn. (7), one can get

( ) ( ) ( ) ( ) p 0 n c p c C S t d St N t S t G ?I Î?" R Î?" dt 1 ?S t + = + + (8)

Where the parameters R p and G 0 are defined by [19],

p p p ? R C = , ()2 13 0 nom G D J 2 10 = ? × .

Also, D= a constant and

n nom a I J V = . stimulated component ( ) ( ) ( ) 0 N t S t G 1 ?S t +

. These two components are modeled by two (I 3 and I 2 ) current sources as shown in Fig. 3. Thus, the light output is proportional to the output node in voltage representation. The voltage representation is applicable if transmission channel and receiver circuit are included in the simulation. Now from Eqns. ( 4) and ( 8), the total equivalent circuit for a single QW laser has been illustrated in Fig. 4.

V. Input Current (mA) The results of PSPICE circuit model for InGaN based laser developed according to the electrical equivalent circuit discussed in section IV, is presented in this section. The parameters used for the PSPICE simulation are listed in Table 1.

8. PSPICE CIRCUIT SIMULATION RESULTS

Output Power (mW)

9. CONCLUSION

A detailed electrical equivalent circuit model of 1.55 ?m InGaN based laser has been studied numerically. The characteristics are realized through the development of the equivalent circuit modeling of the quantum well laser. The electrical circuit modeling of the laser is important to find out the electrical parameters. The PSPICE circuit simulation resulted in an increase in output power with the increase of input current. Threshold current of approximately 6 mA, bias voltage of 1.20 volts, slope efficiency of 0.368 W/A and turn on delay of 3 ns have been found from this circuit analysis. These electrical properties present the richness of InGaN based lasers, and are in agreement with the results of numerical simulations of the same model. Attention on ECM for the laser is important to understanding the electrical mechanism, and requires exhaustive investigation to be matched with electrical automatic power control, modulation scheme, level shifter and slow start circuits.

Figure 1. Fig. 1 :
1Fig.1: Schematic structure of the proposed InGaN based Quantum Well Laser (After Ref.[16]).
Figure 2. =
the carrier recombination rate = AN+BN 2 +CN
Figure 3. Fig. 2 :
2Fig. 2: PSP CE circuit model of Eqn. (4).
Figure 4. Fig. 3 :
3Fig. 3: PSPI CE circuit model of Eqn. (8).
Figure 5. Table 1 :
1
Parameter Unit Value
R e ? 0.468
R p ? 29.4
R s ? 2.0
? ns ns 2.25
? np ns 3
C p pF 0.102
C d pF 10
S c m -3 10 18
D V -1 A -1 m 6 1.79x10 -29
? s - 10 -5
1

Appendix A

  1. Quantum confinement effect on the electronic and optical features of InGaN-based solar cells with InGaN/GaN superlattices as the absorption layers. A Laref , A Altujar , S Laref , S J Luo . Solar Energy 2017. 2016. 142 p. .
  2. Large Signal Circuit Model of Two-Section Gain Lever Quantum Dot Laser. H Ashkan , M S Zahra , F Rahim . Chinese Physics Letters 2012. 29 (11) p. 114207.
  3. Design of High-Speed CMOS Laser Driver Using a Standard CMOS Technology for Optical Data Transmission, H H Seok . November, 2004. Atlanta, GA. 30332.
  4. Semiconductor Devices: Basic Principles, Jasprit Sing . July 2000.
  5. Recombination, gain, band structure, efficiency, and reliability of 1.5 µm GaInNAsSb/GaAs lasers. L L Goddard , R S Bank , A M Wistey , B H Tuen , R Zhilong , S J Harris . Journal of Applied Physics April 2005. 97 (8) p. .
  6. Op to-Electro-Thermal Model for MQW Laser Including Self-Heating and Chirping effects. M Dehghan , V Ahmadi . International Journal of Computer Science and Network Security March 2008. 8 (3) p. .
  7. Equivalent Circuit Model of Quantum-Well Lasers. M F Lu , J S Deng , C Juang , M J Jou , B J Lee . IEEE Journal of Quantum Electronics August 1995. 31 (8) p. .
  8. Circuit-Level Implementation of Semiconductor Self-Assembled Quantum Dot Laser. M H Yavari , V Ahmadi . Journal of Quantum Electronics 2009. 15 (3) p. . (Selected Topics in IEEE)
  9. Ultrafast integrated semiconductor laser technology at 1.55 ?m, M J R Heck . 2008. Eindhoven. Technische Universiteit Eindhoven
  10. White light source employing a III-nitride based laser diode pumping a phosphor. M K Kathryn , S S James , A P Nathan , P D Steven . US 9611987 B2, Apr 4, 2017.
  11. Design and performance of 1.55 ?m laser using InGaN. M T Hasan , M J Islam , R. -U Hasan , M S Islam , S Yeasmin , A G Bhuiyan , M R Islam , A Yamamoto . Physica Status Solidi C July 2010. 7 (7-8) p. .
  12. Fundamentals of Semiconductor Lasers, N Takahiro . 2004. Springer-Verlag New York Inc.
  13. Theoretical Studies of the Effect of Strain on Performance of Strained Quantum Well Lasers Based on GaAs and InP Technology. P J Loehr , J Singh . IEEE Journal of Quantum Electronics March 1991. 27 (3) p. .
  14. GaInNAsSb/GaNAs quantum-well VCSELs, Modeling and physical analysis in the 1.50-1.55µm wavelength range. P R Sarzala , W Nakwaski . Journal of Applied Physics April 2007. 101 (7) p. .
  15. Circuit modeling of the effect of diffusion on damping in a narrow-stripe semiconductor laser. R S Tucker , D J Pope . IEEE Journal of Quantum Electronics 1983. 19 (7) p. .
  16. Large-Signal circuit model for simulation of injection-laser modulation dynamics. R S Tucker . IEE Proceedings on Solid-State and Electron Devices October 1981. 128 (5) p. .
  17. Piezoelectric and thermal effects on optical properties of violet-blue InGaN lasers. S. -H Yena , B. -T Lioub , M. -L Chena , Y. -K Kuo . Proceedings of SPIE Jan 2005. 5628 p. .
  18. Recent progress in an 'ultrahigh speed, ultra-large capacity, ultra-long distance. S Yu , M Luo , X Li , R Hu , Y Qiu , C Li , W Liu , Z He , T Zeng , Q Yang . Chinese Optical Letters 2016. 14 p. 120003.
  19. US) Equivalent Circuit-Level Characterization of 1.55 µm Ingan Laser. Global Journals Inc 2017.
  20. Dynamic Modeling of Terahertz Quantum Cascade Lasers. Y Petitjean , F Destic , J C Mollier , C Sirtori . IEEE Journal of Selected Topics in Quantum Electronics 2011. 17 (1) p. .
  21. Fem to second laser direct writing of microholes on roughened ZnO for output power enhancement of InGaN light-emitting diodes. Z Zang , X Zeng , J Du , M Wang , X Tang . Optical Letters 2016. 41 p. .
Notes
1
© 2017 Global Journals Inc. (US)Equivalent Circuit-Level Characterization of 1.55 µm Ingan Laser
Home 
Date: 2017-01-15