Acne vulgarism treatment using ultra-short laser pulse generated by micro- and nano-ring resonator system

Abstract

Acne vulgaris is adebilitating dermatologic disease, and is conventionally treated by laser therapy using a microring resonator system. An evolving understanding of laser-tissue interactions involving Propioni bacterium acneproducing porphyrins, and the development of lasers to target the sebaceous glands, has led to the development of an escalating number of laser light for acne treatment. The results show that the full width at half maximum of the proposed laser pulse of 0.15 nm can be generated using a microring resonator system. The power of the laser is 200 W and the wavelength laser is 1,032 nm, which is proposed as a treatment of acne vulgaris diseases.

Keywords::

• acne
• treatment
• pulse lasers
• radiofrequency
• photodynamic therapy
• microring resonator

Introduction

Acne vulgaris is one of the most prevalent and potentially physically and emotionally debilitating dermatologic diseases which is caused by the overgrowth of sebum, abnormal desquamation of the sebaceous follicle epithelium, and P. acnes proliferation (Bojar and Holland 2004, Inuma et al. 2009, Farrar and Ingam 2004). It affects approximately 40 million adolescents, 25 million adults, and accounts for more than 30% of all visits to the dermatologist (Leyden 2003, Mulder et al. 2001). The pathogenesis of acne has been found on bodies where hair follicle and sebaceous glands are present such as face, upper neck, and chest (Leyden 1995, Habif and Habie 1996). The acne vulgaris has four main interacting factors, i.e. increased sebum production, microbial flora changes, abnormal keratinization, and inflammation (Strasburger 1997, Cunliffe and Simpson 1998, Braun-Falco et al. 2001, Korkut and Piskin 2005). Many treatments have been proposed to control acne vulgaris, such as benzoyl peroxide, antibiotics, sulfur and sodium sulfacetamide, azelaic acid, and retinoids (Keri and Shiman 2009). Clindamycin and erythromycin are the most frequently used agents against P. acnes (Nishijima et al. 1996, Ishida et al. 2008). Acne is conventionally treated with a variety of topical and oral therapies that introduce a considerable number of short-term and potentially significant long-term consequences (Lee et al. 2003, Pawin et al. 2004, Longshore and Hollandsworth 2003, Gollnick and Krautheim 2003, Velicer et al. 2004). The light-based and radiofrequency device manufacturers are addressing the need for efficacious and safe acne treatments with minimal downtime. This is possible through an evolving understanding of laser-tissue interaction involving Propioni bacterium acnes (P. acnes)-produced porphyrins and the development of deep-penetrating infrared non-ablative lasers, which affect sebaceous glands. In addition to lasers, a number of other non-invasive acne treatments have emerged recently, including short- and broad-band visible light (Sigurdsson et al. 1997, Ashkenazi et al. 2003, Elman et al. 2003), photodynamic therapy using non-coherent light (Ashkenazi et al. 2003, Goldman and Boyce 2003), as well as radiofrequency energy (Ruiz-Esparza and Gomez 2003, Elman and Lebzelter 2004, Hirsch and Shalita 2003). In this article, the ring resonator system is, for the first time, proposed to generate ultra short laser pulses for acne treatment. The theory, fabrication, and applications of microring resonators (MRRs) and nanoring resonators (NRRs) have been discussed extensively in the literature (Sumetsky 2004, 2006a, 2006b, 2008, Sumetsky et al. 2005, 2006, 2007a, 2007b, Xu and Brambilla 2007, White et al. 2006, Matsko and Ilchenko 2006, Ilchenko and Matsko, 2006, Little et al. 2005, Xu and Schmidt 2005, Schwelb 2004, Gheorma and Osgood 2002, Yariv 2002, Xue et al. 2005, Jalil et al. 2012). The authors have developed a PANDA configuration based on a ring resonator system for medical applications (Aziz et al. 2012, Jalil et al. 2011a, 2011b, Suwanpayak et al. 2011a, 2011b, Mitatha et al. 2011a, 2011b).

Methods and materials

Laser treatments

Acne commonly affects the face, especially the T-zone, and trunk. Non-inflammatory lesions include open “black” comedones (papules with central darkened impaction) and closed “white” comedones (flat, pale papules). Inflammatory lesions include papules, pustules, and nodules. Secondary bacterial infection (e.g. Staphylococcal aureus) may rarely increase crusting and inflammation. There are five main types of scars. Ice-pick scars are narrow, tapering deeply into the dermis. Rolling scars are wide and shallow. Boxcar scars are well-demarcated, punched-out depressions. Hypertrophic and keloid scars are raised, the latter extending beyond the area of original inflammation (Nguyen and Su 2011).

In non-topical or intralesional anesthetic treatment, according to baseline randomization, the affected areas were treated with a non-overlapping Gaussian pulse of 50 mW using a 7-mm hand piece. Similarly, at these sessions, contralateral sides were treated with a bright soliton pulse with 178 mW using a 7-mm spot size. Two passes of laser treatment were delivered per session and concurrent forced-air cooling was used for epidermal protection. Figure 1 shows the acne scars of a patient.

Figure 1. Common acne scars.

Perifollicular elastolysis presents as truncal follicular atrophy. Despite inter-observer and intra-observer variability, grading of the severity of acne can be useful for monitoring response to therapy. The Leeds-Cunliffe technique is a facial photo-numeric scale that assigns a number from a manual to the patient's presentation. Serial photography is also helpful to investigate Acne vulgarise (Bhardwaj et al. 2005). Psychological assessment is pertinent for those with severe scarring, acne excoriee, and dysmorphophobia (Nguyen and Su 2011).

Laser generation

A monochromatic light source is launched into a ring resonator with constant light field amplitude (E₀) and the router quantum key distribution as shown in Figure 1, which is the combination of terms in attenuation (α) and phase (f₀) constants, which results in temporal coherence degradation. Hence, the time-dependent input light field (E_in), without pumping term, can be expressed as

where L is a propagation distance (waveguide length).

It is assumed that the nonlinearity of the optical ring resonator is of the Kerr-type; i.e., the refractive index is given by

where n₀ and n₂ are the linear and nonlinear refractive indexes, respectively. I and P are the optical intensity and optical power, respectively. The effective mode core area of the device is given by A_eff. For the microring and nanoring resonators, the effective mode core areas range from 0.10 to 0.50 μm² (Mithata et al. 2009).

When a Gaussian pulse is input and propagated within a fiber ring resonator, the resonant output is formed, thus the normalized output of the light field is the ratio between the output and input fields (E_out(t) and Ein(t)) in each roundtrip, which can be expressed as

Equation (3) indicates that a ring resonator in this particular case is very similar to a Fabry-Perot cavity, which has an input and output mirror with a field reflectivity, (1-κ), and a fully reflecting mirror. k is the coupling coefficient, and represents a roundtrip loss coefficient, and are the linear and nonlinear phase shifts, and is the wave propagation number in a vacuum, where L and α are a waveguide length and linear absorption coefficient, respectively. In this work, the iterative method is introduced to obtain the results as shown in Equation (4) when the output field is connected and input into the other ring resonators.

Results

Two kinds of input pulses (Gaussian and bright soliton) are used to generate an ultra-short laser pulse. Input power for Gaussian pulse is 2.mW and for the bright soliton is 10mw. Spatial and temporal modes are investigated by simulation with three different center wavelengths (1.3, 1.2, and 1.1 µm) for both types of input pulses. The output of the first ring (R₁) is chaotic signal and cancellation chaotic signal is achieved by the second (R₂) and the third rings (R₃). The parameters of ring radii are 18µm, 10 µm, and 5 µm for R₁-R₃, respectively, as shown in Figure 2, and the couple coefficient of the rings are 0.89, 0.62, and 0.99. Figure 3 shows the results of the ring resonator with Gaussian pulse 2.5 W as input signal. The center wavelength is 1.3 µm and the output signal has 4 wavelengths that are 1,010 nm, 1,070 nm, 1,095 nm, and 1,180 nm. Table 1 shows the corresponding values of ring parameters used to generate ultra-shot pulses for spatial mode and temporal mode for Gaussian input pulse at different center wavelengths. Figure 4 shows the results of the ring resonator with bright soliton pulse 10 mW as input signal for spatial mode and temporal mode with center wave length 1.3 µm. The output of the first ring (R₁) is chaotic signal and cancellation chaotic signal is achieved by the second (R₂) and the third rings (R₃). The parameters of ring radii are given in Table 2 for center wavelengths 1.1, 1.2, and 1.3 µm. Figure 5 shows the full-width t half maximum at 0.15 nm, which is the smallest laser coherence and non-effect for good cells in acne.

Figure 2. Diagram generation 1,032 nm laser treatments, where MRR: Microring resonator, NRR: Nanoring resonator, R_i: Ring radii, K_i: Coupling constants.

Figure 3. Ultra-short pulse generation at center wavelength of 1.3 µm for (i) spatial mode and (ii) temporal mode, respectively, using Gaussian pulse.

Figure 4. Ultra-short pulse generation for spatial mode at center wavelength 1.3 µm for (i) patial mode and (ii) temporal mode, respectively, using bright soliton pulse.

Figure 5. Full width at half maximum: FWHM for temporal mode at center wavelength of 1.3µm using Gaussian pulse.

Table 1. Ring parameters used to generate ultra-short pulse for spatial and temporal modes for Gaussian input pulse at different center wavelengths.

Mode	R1 (µm)	R2 (µm)	R3 (µm)	K1	K2	K3	FWHM (nm)	Output power (mw)	Center wavelength
Spatial	15	10	3.2	0.92	0.95	0.96	0.8	38	1.1
Spatial	10	5	3	0.78	0.98	0.95	3	48	1.2
Spatial	10	5	3	0.78	0.98	0.95	15	50	1.3
Temporal	5	2	1	0.81	0.98	0.97	2	42	1.1
Temporal	10	6	2	0.81	0.98	0.98	3	37	1.2
Temporal	15.2	3	5.2	0.89	0.62	0.85	1	120	1.3

Table 2. Ring parameters used to generate ultra-short pulse for spatial and temporal modes for bright soliton input pulse at different center wavelengths.

Modes	R1 (µm)	R2 (µm)	R3 (µm)	K1	K2	K3	FWHM (nm)	Output power (mw)	Center wavelength (µm)
Spatial	5	5	5	0.52	0.68	0.76	0.3	275	1.1
Spatial	5	4	3	0.62	0.78	0.91	1.3	191	1.2
Spatial	10	5	3	0.5	0.6	0.93	0.4	178	1.3
Temporal	15	7	3.2	0.88	0.92	0.95	0.9	285	1.1
Temporal	10	5	3.1	0.88	0.92	0.95	0.27	265	1.2
Temporal	10	5	3.1	0.88	0.92	0.95	0.6	289	1.3

Conclusion

A new generation of laser therapy by microring resonator can be used for acne vulgarism treatment. It is a simple, small, portable, and comfortable technique. The microring resonator can be fabricated on a chip, which can be built in the pen using the smallest needle. In the near future, this system can be applied for microring lasercosmetic procedures. This investigation focused on the generation of controlled ultra-short laser pulses by a microring resonator system to treat acne vulgarism. This study emphasizes the temporal and spatial profiles and parameters which control ultra-short pulses in acne vulgaris treatment. Details of design and fabrication are given in the cited references.

Acknowledgements

We would like to thank the Institute of Advanced Photonics Science, Nanotechnology Research Alliance, Universiti Teknologi Malaysia (UTM), and King Mongkut's Institute of Technology (KMITL), Thailand, for providing the research facilities. This research work has been supported by UTM's Tier 1/Flagship Research Grant, MyBrain15 Fellowship/MOHE SLAI Fellowship, and the Ministry of Higher Education (MOHE) research grant. N. Suwanpayak would like to acknowledge King Mongkut's Institute of Technology Ladkrabang, Bangkok (KMITL), Thailand, for the partial support in higher education at KMITL, Thailand.

Declaration of interest

The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.