सामयिक विषय: Scientific

Unconventional laser based on 'bound states in the continuum' (BIC)

Unconventional laser based on ‘bound states in the continuum’ (BIC)

Question: scientists of which country demonstrated the world’s first laser based on an unconventional wave physics phenomenon called bound states in the continuum.
(a) USA
(b) BRITAIN
(c) CHINA
(d) JAPAN
Ans: (a)
Related facts:

  • Researchers Yeshaiahu Fainman,Boubacar Kante,Ashok Kodigla and Babak Bahari at the University of California San Diego (USA) have demonstrated the world’s first laser based on an unconventional wave physics phenomenon called Bound states In the Continuum (BIC).
  • Bound states in the continuum (BICs) are phenomena that have been predicted to exist since 1929.
  • BICs are waves that remain perfectly confined, or bound, in an open system.
  • Conventional waves in an open system escape, but BICs defy this norm — they stay localized and do not escape despite having open pathways to do so.
  • The BIC laser in this work is constructed from a thin semiconductor membrane made of indium, gallium, arsenic and phosphorus ( indium gallium arsenide phosphide (InGaAsP).
  • The membrane is structured as an array of nano-sized cylinders suspended in air. The cylinders are interconnected by a network of supporting bridges, which provide mechanical stability to the device. Surface lasing occurred for geometries with nanoresonator arrays as small as 8 x 8 particles.
  • By powering the membrane with a high frequency laser beam, researchers induced the BIC system to emit its own lower frequency laser beam (at telecommunication frequency).
  • The popular VCSEL [vertical-cavity surface-emeitting laser] may one day be replaced by the ‘BICSEL’— bound state in the continuum surface-emitting laser, which could lead to smaller devices that consume less power,
  • The technology could revolutionize the development of surface lasers, making them more compact and energy-efficient for communications and computing applications.
  • The new BIC lasers could also be developed as high-power lasers for industrial and defense applications.
  • BIC lasers can be readily tuned to emit beams of different wavelengths, a useful feature for medical lasers made to precisely target cancer cells without damaging normal tissue.
  • BIC lasers can also be made to emit beams with specially engineered shapes (spiral, donut or bell curve) — called vector beams — which could enable increasingly powerful computers and optical communication systems that can carry up to 10 times more information than existing ones.

Reference:
www.laserfocusworld.com/…/unconventional-laser
www.sciencenewsline.com/…/2017011208000030.ht

Two per cent reduction in Water level of 91 major Reservoirs

Two per cent reduction in Water level of 91 major Reservoirs

Question: When was the fourth edition of India Water Week observed?
(a) 04 to 08 April, 2016.
(b) 12-17 March, 2016
(c) 22-28 February, 2016
(d) None of the above.
Ans: (a)
Related facts:

  • The Water storage available in 91 major reservoirs of the country for the week ending on January 19, 2017 was 82.915 BCM, which is 53% of total storage capacity of these reservoirs.
  • This was 126%of the storage of corresponding period of last year and 99% of storage of average of last ten years.
  • The total storage capacity of these 91 reservoirs is 157.799 BCM which is about 62% of the total storage capacity of 253.388 BCM which is estimated to have been created in the country. 37 Reservoirs out of these 91 have hydropower benefit with installed capacity of more than 60 MW.
  • The northern region which includes States of Himachal Pradesh, Punjab and Rajasthan has 6 reservoirs having total live storage capacity of 18.01 BCM.
  • The total live storage available in these reservoirs is 14.00 BCM which is 74% of total live storage capacity of these reservoirs.
  • The Western region includes States of Gujarat and Maharashtra. There are 27 reservoirs under CWC monitoring having total live storage capacity of 27.07 BCM. The total live storage available in these reservoirs is 17.55 BCM which is 65% of total live storage capacity of these reservoirs.
  • The Central region includes States of Uttar Pradesh, Uttarakhand, Madhya Pradesh and Chhattisgarh. There are 12 reservoirs under CWC monitoring having total live storage capacity of 42.30 BCM. The total live storage available in these reservoirs is 28.50 BCM which is 67% of total live storage capacity of these reservoirs.
  • The Southern region includes States of Andhra Pradesh, Telangana, AP&TG (Two combined projects in both states) Karnataka, Kerala and Tamil Nadu. There are 31 reservoirs under CWC monitoring having total live storage capacity of 51.59 BCM. The total live storage available in these reservoirs is 15.59 BCM which is 30% of total live storage capacity of these reservoirs.
  • States having better storage than last year for corresponding period are Punjab, Rajasthan, Jharkhand, Odisha, West Bengal, Gujarat, Maharashtra, Uttar Pradesh, Madhya Pradesh, Chhattisgarh, AP&TG (Two combined projects in both states), Telangana and Karnataka.
  • States having lesser storage than last year for corresponding period are Himachal Pradesh, Tripura, Uttarakhand, Andhra Pradesh, Kerala and Tamil Nadu.
  • Its notable that Ministry of Water Resources, River Development and Ganga Rejuvenation, Government of India has been organising India Water Week since 2012 as an annual international event. The fourth edition of India Water Week was organised during 4th to 8th April, 2016.
  • Many reputed national and international organizations, research institutes and NGOs from water resources sector, agriculture, power etc. participate in the event to share their knowledge and experience in the water management and water governance sector.

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Reference:
http://pib.nic.in/newsite/PrintRelease.aspx
http://wrmin.nic.in/forms/list.aspx?lid=642

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